第八章：错误处理与异常 - 在线学习与练习平台

错误处理是PHP开发中的重要环节，良好的错误处理机制能够提高应用程序的稳定性和用户体验。本章将详细介绍PHP中的错误类型、异常处理机制、自定义异常、调试技巧以及最佳实践。

8.1 PHP错误类型

8.1.1 错误级别

<?php
// PHP错误级别演示
echo "=== PHP错误级别演示 ===\n";

// 1. 致命错误 (Fatal Error) - E_ERROR
// 这些错误会导致脚本停止执行
// function fatalErrorDemo() {
//     call_to_undefined_function(); // 调用未定义函数
// }
// fatalErrorDemo();

// 2. 警告 (Warning) - E_WARNING
// 脚本继续执行，但会显示警告信息
echo "--- 警告演示 ---\n";
include 'non_existent_file.php'; // 包含不存在的文件
echo "警告后脚本继续执行\n";

// 3. 注意 (Notice) - E_NOTICE
// 脚本继续执行，显示注意信息
echo "\n--- 注意演示 ---\n";
echo $undefined_variable; // 使用未定义变量
echo "注意后脚本继续执行\n";

// 4. 解析错误 (Parse Error) - E_PARSE
// 语法错误，脚本无法运行
// echo "解析错误演示
// 缺少引号会导致解析错误

// 5. 严格标准 (Strict Standards) - E_STRICT
// PHP 7+ 中的严格类型检查
declare(strict_types=1);

function strictDemo(int $number): string {
    return (string)$number;
}

echo "\n--- 严格模式演示 ---\n";
echo strictDemo(123) . "\n";
// echo strictDemo("123"); // 在严格模式下会报错

// 6. 用户错误 - E_USER_ERROR, E_USER_WARNING, E_USER_NOTICE
echo "\n--- 用户自定义错误 ---\n";
trigger_error("这是用户定义的错误", E_USER_ERROR);
?>

8.1.2 错误报告设置

<?php
// 错误报告配置
echo "=== 错误报告配置 ===\n";

// 获取当前错误报告级别
echo "当前错误报告级别：" . error_reporting() . "\n";

// 显示所有错误
error_reporting(E_ALL);
ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);

// 只显示致命错误和警告
// error_reporting(E_ERROR | E_WARNING);

// 关闭错误显示（生产环境推荐）
// error_reporting(0);
// ini_set('display_errors', 0);

// 记录错误到日志文件
ini_set('log_errors', 1);
ini_set('error_log', 'php_errors.log');

// 自定义错误处理函数
function customErrorHandler($errno, $errstr, $errfile, $errline) {
    $errorTypes = [
        E_ERROR => 'Fatal Error',
        E_WARNING => 'Warning',
        E_NOTICE => 'Notice',
        E_USER_ERROR => 'User Error',
        E_USER_WARNING => 'User Warning',
        E_USER_NOTICE => 'User Notice',
        E_STRICT => 'Strict Standards',
        E_RECOVERABLE_ERROR => 'Recoverable Error',
        E_DEPRECATED => 'Deprecated',
        E_USER_DEPRECATED => 'User Deprecated'
    ];
    
    $errorType = isset($errorTypes[$errno]) ? $errorTypes[$errno] : 'Unknown Error';
    
    $message = "[$errorType] $errstr in $errfile on line $errline";
    
    // 记录到日志
    error_log($message);
    
    // 显示友好的错误信息
    echo "<div style='color: red; border: 1px solid red; padding: 10px; margin: 5px;'>";
    echo "<strong>$errorType:</strong> $errstr<br>";
    echo "<small>File: $errfile, Line: $errline</small>";
    echo "</div>";
    
    // 对于致命错误，停止执行
    if ($errno === E_USER_ERROR) {
        exit(1);
    }
    
    return true; // 阻止PHP内置错误处理
}

// 注册自定义错误处理器
set_error_handler('customErrorHandler');

// 测试自定义错误处理
echo "\n--- 自定义错误处理测试 ---\n";
echo $undefined_var; // 触发Notice
trigger_error("自定义警告消息", E_USER_WARNING);

// 恢复默认错误处理
restore_error_handler();
?>

8.1.3 错误处理最佳实践

<?php
// 错误处理最佳实践
class ErrorHandler {
    private $logFile;
    private $displayErrors;
    
    public function __construct($logFile = 'app_errors.log', $displayErrors = false) {
        $this->logFile = $logFile;
        $this->displayErrors = $displayErrors;
        
        // 注册错误和异常处理器
        set_error_handler([$this, 'handleError']);
        set_exception_handler([$this, 'handleException']);
        register_shutdown_function([$this, 'handleFatalError']);
    }
    
    /**
     * 处理一般错误
     */
    public function handleError($errno, $errstr, $errfile, $errline) {
        // 如果错误被@操作符抑制，则不处理
        if (!(error_reporting() & $errno)) {
            return false;
        }
        
        $errorInfo = [
            'type' => $this->getErrorType($errno),
            'message' => $errstr,
            'file' => $errfile,
            'line' => $errline,
            'timestamp' => date('Y-m-d H:i:s'),
            'trace' => debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS)
        ];
        
        $this->logError($errorInfo);
        
        if ($this->displayErrors) {
            $this->displayError($errorInfo);
        }
        
        // 致命错误停止执行
        if ($errno === E_USER_ERROR) {
            exit(1);
        }
        
        return true;
    }
    
    /**
     * 处理未捕获的异常
     */
    public function handleException($exception) {
        $errorInfo = [
            'type' => 'Uncaught Exception',
            'message' => $exception->getMessage(),
            'file' => $exception->getFile(),
            'line' => $exception->getLine(),
            'timestamp' => date('Y-m-d H:i:s'),
            'trace' => $exception->getTrace(),
            'class' => get_class($exception)
        ];
        
        $this->logError($errorInfo);
        
        if ($this->displayErrors) {
            $this->displayError($errorInfo);
        } else {
            echo "An error occurred. Please try again later.";
        }
    }
    
    /**
     * 处理致命错误
     */
    public function handleFatalError() {
        $error = error_get_last();
        
        if ($error && in_array($error['type'], [E_ERROR, E_PARSE, E_CORE_ERROR, E_COMPILE_ERROR])) {
            $errorInfo = [
                'type' => 'Fatal Error',
                'message' => $error['message'],
                'file' => $error['file'],
                'line' => $error['line'],
                'timestamp' => date('Y-m-d H:i:s')
            ];
            
            $this->logError($errorInfo);
            
            if ($this->displayErrors) {
                $this->displayError($errorInfo);
            } else {
                echo "A fatal error occurred. Please contact support.";
            }
        }
    }
    
    /**
     * 记录错误到日志文件
     */
    private function logError($errorInfo) {
        $logMessage = sprintf(
            "[%s] %s: %s in %s on line %d\n",
            $errorInfo['timestamp'],
            $errorInfo['type'],
            $errorInfo['message'],
            $errorInfo['file'],
            $errorInfo['line']
        );
        
        if (isset($errorInfo['trace'])) {
            $logMessage .= "Stack trace:\n";
            foreach ($errorInfo['trace'] as $i => $frame) {
                $logMessage .= sprintf(
                    "#%d %s(%d): %s%s%s()\n",
                    $i,
                    $frame['file'] ?? '[internal function]',
                    $frame['line'] ?? 0,
                    $frame['class'] ?? '',
                    $frame['type'] ?? '',
                    $frame['function'] ?? ''
                );
            }
        }
        
        $logMessage .= "\n";
        
        file_put_contents($this->logFile, $logMessage, FILE_APPEND | LOCK_EX);
    }
    
    /**
     * 显示错误信息
     */
    private function displayError($errorInfo) {
        echo "<div style='background: #ffebee; border: 1px solid #f44336; padding: 15px; margin: 10px 0; border-radius: 4px;'>";
        echo "<h3 style='color: #d32f2f; margin: 0 0 10px 0;'>{$errorInfo['type']}</h3>";
        echo "<p><strong>Message:</strong> {$errorInfo['message']}</p>";
        echo "<p><strong>File:</strong> {$errorInfo['file']}</p>";
        echo "<p><strong>Line:</strong> {$errorInfo['line']}</p>";
        echo "<p><strong>Time:</strong> {$errorInfo['timestamp']}</p>";
        
        if (isset($errorInfo['trace']) && !empty($errorInfo['trace'])) {
            echo "<details><summary><strong>Stack Trace</strong></summary>";
            echo "<pre style='background: #f5f5f5; padding: 10px; overflow-x: auto;'>";
            foreach ($errorInfo['trace'] as $i => $frame) {
                printf(
                    "#%d %s(%d): %s%s%s()\n",
                    $i,
                    $frame['file'] ?? '[internal function]',
                    $frame['line'] ?? 0,
                    $frame['class'] ?? '',
                    $frame['type'] ?? '',
                    $frame['function'] ?? ''
                );
            }
            echo "</pre></details>";
        }
        echo "</div>";
    }
    
    /**
     * 获取错误类型名称
     */
    private function getErrorType($errno) {
        $errorTypes = [
            E_ERROR => 'Fatal Error',
            E_WARNING => 'Warning',
            E_NOTICE => 'Notice',
            E_USER_ERROR => 'User Error',
            E_USER_WARNING => 'User Warning',
            E_USER_NOTICE => 'User Notice',
            E_STRICT => 'Strict Standards',
            E_RECOVERABLE_ERROR => 'Recoverable Error',
            E_DEPRECATED => 'Deprecated',
            E_USER_DEPRECATED => 'User Deprecated'
        ];
        
        return isset($errorTypes[$errno]) ? $errorTypes[$errno] : 'Unknown Error';
    }
}

// 使用错误处理器
echo "=== 错误处理器演示 ===\n";

// 开发环境 - 显示错误
$errorHandler = new ErrorHandler('dev_errors.log', true);

// 生产环境 - 不显示错误
// $errorHandler = new ErrorHandler('prod_errors.log', false);

// 测试错误处理
echo "测试Notice错误：";
echo $undefined_variable;

echo "\n测试Warning错误：";
include 'non_existent_file.php';

echo "\n测试用户错误：";
trigger_error("这是一个用户定义的错误", E_USER_WARNING);
?>

8.2 异常处理机制

8.2.1 异常基础

<?php
// 异常处理基础
echo "=== 异常处理基础 ===\n";

// 基本的try-catch结构
try {
    echo "尝试执行可能出错的代码\n";
    
    // 抛出异常
    throw new Exception("这是一个测试异常", 1001);
    
    echo "这行代码不会执行\n";
} catch (Exception $e) {
    echo "捕获到异常：" . $e->getMessage() . "\n";
    echo "异常代码：" . $e->getCode() . "\n";
    echo "异常文件：" . $e->getFile() . "\n";
    echo "异常行号：" . $e->getLine() . "\n";
}

echo "异常处理后继续执行\n\n";

// try-catch-finally结构
echo "--- try-catch-finally演示 ---\n";

function testFinally($throwException = false) {
    try {
        echo "执行try块\n";
        
        if ($throwException) {
            throw new Exception("测试异常");
        }
        
        echo "try块正常结束\n";
        return "try返回值";
    } catch (Exception $e) {
        echo "执行catch块：" . $e->getMessage() . "\n";
        return "catch返回值";
    } finally {
        echo "执行finally块（总是执行）\n";
        // finally块中的return会覆盖try/catch的return
        // return "finally返回值";
    }
}

echo "正常情况：\n";
$result1 = testFinally(false);
echo "返回值：$result1\n\n";

echo "异常情况：\n";
$result2 = testFinally(true);
echo "返回值：$result2\n\n";

// 多个catch块
echo "--- 多个catch块演示 ---\n";

function multiCatchDemo($type) {
    try {
        switch ($type) {
            case 'invalid':
                throw new InvalidArgumentException("无效参数异常");
            case 'runtime':
                throw new RuntimeException("运行时异常");
            case 'logic':
                throw new LogicException("逻辑异常");
            default:
                throw new Exception("通用异常");
        }
    } catch (InvalidArgumentException $e) {
        echo "处理无效参数异常：" . $e->getMessage() . "\n";
    } catch (RuntimeException $e) {
        echo "处理运行时异常：" . $e->getMessage() . "\n";
    } catch (LogicException $e) {
        echo "处理逻辑异常：" . $e->getMessage() . "\n";
    } catch (Exception $e) {
        echo "处理通用异常：" . $e->getMessage() . "\n";
    }
}

multiCatchDemo('invalid');
multiCatchDemo('runtime');
multiCatchDemo('logic');
multiCatchDemo('other');

// PHP 7.1+ 多异常类型捕获
echo "\n--- 多异常类型捕获 ---\n";

try {
    throw new InvalidArgumentException("参数错误");
} catch (InvalidArgumentException | RuntimeException $e) {
    echo "捕获到参数错误或运行时错误：" . $e->getMessage() . "\n";
} catch (Exception $e) {
    echo "捕获到其他异常：" . $e->getMessage() . "\n";
}
?>

8.2.2 异常传播和重新抛出

<?php
// 异常传播和重新抛出
echo "=== 异常传播演示 ===\n";

function level3() {
    echo "Level 3: 抛出异常\n";
    throw new Exception("来自Level 3的异常");
}

function level2() {
    echo "Level 2: 调用Level 3\n";
    level3();
    echo "Level 2: 这行不会执行\n";
}

function level1() {
    try {
        echo "Level 1: 调用Level 2\n";
        level2();
        echo "Level 1: 这行不会执行\n";
    } catch (Exception $e) {
        echo "Level 1: 捕获异常 - " . $e->getMessage() . "\n";
        echo "异常追踪：\n" . $e->getTraceAsString() . "\n";
    }
}

level1();

echo "\n--- 异常重新抛出演示 ---\n";

class DatabaseException extends Exception {}
class ConnectionException extends DatabaseException {}
class QueryException extends DatabaseException {}

class Database {
    private $connected = false;
    
    public function connect() {
        // 模拟连接失败
        if (rand(0, 1)) {
            throw new ConnectionException("数据库连接失败");
        }
        $this->connected = true;
        echo "数据库连接成功\n";
    }
    
    public function query($sql) {
        if (!$this->connected) {
            throw new QueryException("数据库未连接");
        }
        
        // 模拟查询错误
        if (strpos($sql, 'DROP') !== false) {
            throw new QueryException("危险的SQL操作被阻止");
        }
        
        echo "执行查询：$sql\n";
        return "查询结果";
    }
}

class UserService {
    private $db;
    
    public function __construct() {
        $this->db = new Database();
    }
    
    public function getUser($id) {
        try {
            $this->db->connect();
            $result = $this->db->query("SELECT * FROM users WHERE id = $id");
            return $result;
        } catch (ConnectionException $e) {
            // 记录连接错误并重新抛出
            error_log("数据库连接错误：" . $e->getMessage());
            throw new Exception("服务暂时不可用，请稍后重试", 503, $e);
        } catch (QueryException $e) {
            // 记录查询错误并重新抛出
            error_log("查询错误：" . $e->getMessage());
            throw new Exception("数据查询失败", 500, $e);
        }
    }
}

class UserController {
    private $userService;
    
    public function __construct() {
        $this->userService = new UserService();
    }
    
    public function showUser($id) {
        try {
            $user = $this->userService->getUser($id);
            echo "用户信息：$user\n";
        } catch (Exception $e) {
            echo "错误：" . $e->getMessage() . "\n";
            echo "HTTP状态码：" . $e->getCode() . "\n";
            
            // 显示原始异常信息（开发环境）
            if ($e->getPrevious()) {
                echo "原始错误：" . $e->getPrevious()->getMessage() . "\n";
            }
        }
    }
}

// 测试异常传播和重新抛出
$controller = new UserController();
$controller->showUser(123);
?>

8.2.3 自定义异常类

<?php
// 自定义异常类
echo "=== 自定义异常类演示 ===\n";

// 基础自定义异常
class BaseException extends Exception {
    protected $context = [];
    
    public function __construct($message = "", $code = 0, Exception $previous = null, array $context = []) {
        parent::__construct($message, $code, $previous);
        $this->context = $context;
    }
    
    public function getContext() {
        return $this->context;
    }
    
    public function setContext(array $context) {
        $this->context = $context;
    }
    
    public function addContext($key, $value) {
        $this->context[$key] = $value;
    }
    
    public function toArray() {
        return [
            'message' => $this->getMessage(),
            'code' => $this->getCode(),
            'file' => $this->getFile(),
            'line' => $this->getLine(),
            'context' => $this->context,
            'trace' => $this->getTrace()
        ];
    }
    
    public function __toString() {
        $output = get_class($this) . ": {$this->getMessage()}\n";
        $output .= "File: {$this->getFile()}\n";
        $output .= "Line: {$this->getLine()}\n";
        
        if (!empty($this->context)) {
            $output .= "Context: " . json_encode($this->context) . "\n";
        }
        
        return $output;
    }
}

// 业务异常类
class ValidationException extends BaseException {
    private $errors = [];
    
    public function __construct($message = "Validation failed", array $errors = [], $code = 422) {
        parent::__construct($message, $code);
        $this->errors = $errors;
    }
    
    public function getErrors() {
        return $this->errors;
    }
    
    public function addError($field, $message) {
        $this->errors[$field][] = $message;
    }
    
    public function hasErrors() {
        return !empty($this->errors);
    }
}

class AuthenticationException extends BaseException {
    public function __construct($message = "Authentication failed", $code = 401) {
        parent::__construct($message, $code);
    }
}

class AuthorizationException extends BaseException {
    private $requiredPermission;
    
    public function __construct($message = "Access denied", $requiredPermission = null, $code = 403) {
        parent::__construct($message, $code);
        $this->requiredPermission = $requiredPermission;
    }
    
    public function getRequiredPermission() {
        return $this->requiredPermission;
    }
}

class ResourceNotFoundException extends BaseException {
    private $resourceType;
    private $resourceId;
    
    public function __construct($resourceType, $resourceId, $code = 404) {
        $message = "$resourceType with ID '$resourceId' not found";
        parent::__construct($message, $code);
        $this->resourceType = $resourceType;
        $this->resourceId = $resourceId;
    }
    
    public function getResourceType() {
        return $this->resourceType;
    }
    
    public function getResourceId() {
        return $this->resourceId;
    }
}

// 使用自定义异常的示例类
class UserValidator {
    public function validate(array $data) {
        $errors = [];
        
        if (empty($data['name'])) {
            $errors['name'][] = '姓名不能为空';
        } elseif (strlen($data['name']) < 2) {
            $errors['name'][] = '姓名至少需要2个字符';
        }
        
        if (empty($data['email'])) {
            $errors['email'][] = '邮箱不能为空';
        } elseif (!filter_var($data['email'], FILTER_VALIDATE_EMAIL)) {
            $errors['email'][] = '邮箱格式无效';
        }
        
        if (empty($data['password'])) {
            $errors['password'][] = '密码不能为空';
        } elseif (strlen($data['password']) < 6) {
            $errors['password'][] = '密码至少需要6个字符';
        }
        
        if (!empty($errors)) {
            throw new ValidationException('用户数据验证失败', $errors);
        }
        
        return true;
    }
}

class AuthService {
    private $users = [
        'admin@example.com' => ['password' => 'admin123', 'role' => 'admin'],
        'user@example.com' => ['password' => 'user123', 'role' => 'user']
    ];
    
    public function authenticate($email, $password) {
        if (!isset($this->users[$email])) {
            throw new AuthenticationException('用户不存在');
        }
        
        if ($this->users[$email]['password'] !== $password) {
            throw new AuthenticationException('密码错误');
        }
        
        return $this->users[$email];
    }
    
    public function authorize($user, $permission) {
        if ($user['role'] !== 'admin' && $permission === 'admin') {
            throw new AuthorizationException('需要管理员权限', $permission);
        }
        
        return true;
    }
}

class UserRepository {
    private $users = [
        1 => ['id' => 1, 'name' => '张三', 'email' => 'zhangsan@example.com'],
        2 => ['id' => 2, 'name' => '李四', 'email' => 'lisi@example.com']
    ];
    
    public function findById($id) {
        if (!isset($this->users[$id])) {
            throw new ResourceNotFoundException('User', $id);
        }
        
        return $this->users[$id];
    }
}

// 测试自定义异常
echo "--- 验证异常测试 ---\n";
$validator = new UserValidator();

try {
    $validator->validate([
        'name' => 'A',
        'email' => 'invalid-email',
        'password' => '123'
    ]);
} catch (ValidationException $e) {
    echo "验证失败：" . $e->getMessage() . "\n";
    echo "错误详情：\n";
    foreach ($e->getErrors() as $field => $fieldErrors) {
        echo "  $field: " . implode(', ', $fieldErrors) . "\n";
    }
}

echo "\n--- 认证异常测试 ---\n";
$authService = new AuthService();

try {
    $authService->authenticate('wrong@example.com', 'wrongpassword');
} catch (AuthenticationException $e) {
    echo "认证失败：" . $e->getMessage() . "\n";
    echo "状态码：" . $e->getCode() . "\n";
}

echo "\n--- 授权异常测试 ---\n";
try {
    $user = $authService->authenticate('user@example.com', 'user123');
    $authService->authorize($user, 'admin');
} catch (AuthenticationException $e) {
    echo "认证失败：" . $e->getMessage() . "\n";
} catch (AuthorizationException $e) {
    echo "授权失败：" . $e->getMessage() . "\n";
    echo "需要权限：" . $e->getRequiredPermission() . "\n";
}

echo "\n--- 资源未找到异常测试 ---\n";
$userRepo = new UserRepository();

try {
    $userRepo->findById(999);
} catch (ResourceNotFoundException $e) {
    echo "资源未找到：" . $e->getMessage() . "\n";
    echo "资源类型：" . $e->getResourceType() . "\n";
    echo "资源ID：" . $e->getResourceId() . "\n";
}
?>

8.3 调试技巧

8.3.1 调试函数和工具

<?php
// 调试函数和工具
echo "=== 调试函数演示 ===\n";

// 1. var_dump() - 详细输出变量信息
echo "--- var_dump演示 ---\n";
$array = ['name' => '张三', 'age' => 25, 'hobbies' => ['读书', '游泳']];
var_dump($array);

// 2. print_r() - 可读性更好的输出
echo "\n--- print_r演示 ---\n";
print_r($array);

// 3. var_export() - 输出可执行的PHP代码
echo "\n--- var_export演示 ---\n";
var_export($array);
echo "\n";

// 4. debug_backtrace() - 获取调用栈
echo "\n--- debug_backtrace演示 ---\n";

function debugLevel3() {
    echo "Level 3 调用栈：\n";
    $trace = debug_backtrace();
    foreach ($trace as $i => $frame) {
        echo "#$i {$frame['function']}() called at [{$frame['file']}:{$frame['line']}]\n";
    }
}

function debugLevel2() {
    debugLevel3();
}

function debugLevel1() {
    debugLevel2();
}

debugLevel1();

// 5. debug_print_backtrace() - 直接打印调用栈
echo "\n--- debug_print_backtrace演示 ---\n";

function printBacktraceDemo() {
    debug_print_backtrace();
}

function callPrintBacktrace() {
    printBacktraceDemo();
}

callPrintBacktrace();

// 6. get_defined_vars() - 获取所有已定义变量
echo "\n--- get_defined_vars演示 ---\n";
$localVar = "本地变量";
$anotherVar = 123;

function showDefinedVars() {
    $functionVar = "函数变量";
    $vars = get_defined_vars();
    echo "函数内定义的变量：\n";
    print_r($vars);
}

showDefinedVars();

// 7. memory_get_usage() - 获取内存使用情况
echo "\n--- 内存使用情况 ---\n";
echo "当前内存使用：" . number_format(memory_get_usage()) . " bytes\n";
echo "峰值内存使用：" . number_format(memory_get_peak_usage()) . " bytes\n";

// 创建大数组测试内存使用
$bigArray = range(1, 100000);
echo "创建大数组后内存使用：" . number_format(memory_get_usage()) . " bytes\n";
echo "峰值内存使用：" . number_format(memory_get_peak_usage()) . " bytes\n";

unset($bigArray);
echo "释放数组后内存使用：" . number_format(memory_get_usage()) . " bytes\n";
?>

8.3.2 调试类和工具

<?php
// 调试工具类
class Debugger {
    private static $startTime;
    private static $checkpoints = [];
    private static $queries = [];
    private static $enabled = true;
    
    /**
     * 启用/禁用调试
     */
    public static function enable($enabled = true) {
        self::$enabled = $enabled;
    }
    
    /**
     * 开始计时
     */
    public static function start() {
        if (!self::$enabled) return;
        
        self::$startTime = microtime(true);
        self::$checkpoints = [];
        self::$queries = [];
    }
    
    /**
     * 添加检查点
     */
    public static function checkpoint($label) {
        if (!self::$enabled) return;
        
        $currentTime = microtime(true);
        $elapsed = $currentTime - self::$startTime;
        $memory = memory_get_usage();
        
        self::$checkpoints[] = [
            'label' => $label,
            'time' => $currentTime,
            'elapsed' => $elapsed,
            'memory' => $memory,
            'trace' => debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS, 3)
        ];
    }
    
    /**
     * 记录SQL查询
     */
    public static function logQuery($sql, $params = [], $executionTime = 0) {
        if (!self::$enabled) return;
        
        self::$queries[] = [
            'sql' => $sql,
            'params' => $params,
            'execution_time' => $executionTime,
            'timestamp' => microtime(true),
            'trace' => debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS, 5)
        ];
    }
    
    /**
     * 输出调试信息
     */
    public static function dump($var, $label = null) {
        if (!self::$enabled) return;
        
        echo "<div style='background: #f0f0f0; border: 1px solid #ccc; padding: 10px; margin: 5px 0; font-family: monospace;'>";
        
        if ($label) {
            echo "<strong>$label:</strong><br>";
        }
        
        echo "<pre>";
        var_dump($var);
        echo "</pre>";
        
        $trace = debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS, 1);
        if (!empty($trace)) {
            $caller = $trace[0];
            echo "<small>Called from: {$caller['file']}:{$caller['line']}</small>";
        }
        
        echo "</div>";
    }
    
    /**
     * 生成调试报告
     */
    public static function report() {
        if (!self::$enabled) return;
        
        $totalTime = microtime(true) - self::$startTime;
        $peakMemory = memory_get_peak_usage();
        
        echo "<div style='background: #e8f5e8; border: 1px solid #4caf50; padding: 15px; margin: 10px 0; font-family: Arial, sans-serif;'>";
        echo "<h3 style='margin: 0 0 10px 0; color: #2e7d32;'>调试报告</h3>";
        
        // 总体统计
        echo "<p><strong>总执行时间:</strong> " . number_format($totalTime * 1000, 2) . " ms</p>";
        echo "<p><strong>峰值内存使用:</strong> " . self::formatBytes($peakMemory) . "</p>";
        echo "<p><strong>SQL查询数量:</strong> " . count(self::$queries) . "</p>";
        
        // 检查点详情
        if (!empty(self::$checkpoints)) {
            echo "<h4>执行检查点:</h4>";
            echo "<table style='width: 100%; border-collapse: collapse;'>";
            echo "<tr style='background: #c8e6c9;'><th>标签</th><th>耗时(ms)</th><th>累计时间(ms)</th><th>内存使用</th></tr>";
            
            $lastTime = self::$startTime;
            foreach (self::$checkpoints as $checkpoint) {
                $stepTime = ($checkpoint['time'] - $lastTime) * 1000;
                $totalTime = $checkpoint['elapsed'] * 1000;
                
                echo "<tr>";
                echo "<td>{$checkpoint['label']}</td>";
                echo "<td>" . number_format($stepTime, 2) . "</td>";
                echo "<td>" . number_format($totalTime, 2) . "</td>";
                echo "<td>" . self::formatBytes($checkpoint['memory']) . "</td>";
                echo "</tr>";
                
                $lastTime = $checkpoint['time'];
            }
            echo "</table>";
        }
        
        // SQL查询详情
        if (!empty(self::$queries)) {
            echo "<h4>SQL查询:</h4>";
            foreach (self::$queries as $i => $query) {
                echo "<div style='background: #fff; border: 1px solid #ddd; padding: 8px; margin: 5px 0;'>";
                echo "<strong>查询 #" . ($i + 1) . ":</strong> " . htmlspecialchars($query['sql']) . "<br>";
                
                if (!empty($query['params'])) {
                    echo "<strong>参数:</strong> " . htmlspecialchars(json_encode($query['params'])) . "<br>";
                }
                
                echo "<strong>执行时间:</strong> " . number_format($query['execution_time'] * 1000, 2) . " ms";
                echo "</div>";
            }
        }
        
        echo "</div>";
    }
    
    /**
     * 格式化字节数
     */
    private static function formatBytes($bytes) {
        $units = ['B', 'KB', 'MB', 'GB'];
        $bytes = max($bytes, 0);
        $pow = floor(($bytes ? log($bytes) : 0) / log(1024));
        $pow = min($pow, count($units) - 1);
        
        $bytes /= pow(1024, $pow);
        
        return round($bytes, 2) . ' ' . $units[$pow];
    }
}

// 性能分析器
class Profiler {
    private static $timers = [];
    private static $counters = [];
    
    /**
     * 开始计时
     */
    public static function start($name) {
        self::$timers[$name] = microtime(true);
    }
    
    /**
     * 结束计时
     */
    public static function end($name) {
        if (!isset(self::$timers[$name])) {
            return 0;
        }
        
        $elapsed = microtime(true) - self::$timers[$name];
        unset(self::$timers[$name]);
        
        return $elapsed;
    }
    
    /**
     * 计数器
     */
    public static function increment($name, $value = 1) {
        if (!isset(self::$counters[$name])) {
            self::$counters[$name] = 0;
        }
        self::$counters[$name] += $value;
    }
    
    /**
     * 获取计数器值
     */
    public static function getCounter($name) {
        return isset(self::$counters[$name]) ? self::$counters[$name] : 0;
    }
    
    /**
     * 重置所有计数器
     */
    public static function reset() {
        self::$timers = [];
        self::$counters = [];
    }
    
    /**
     * 获取所有计数器
     */
    public static function getCounters() {
        return self::$counters;
    }
}

// 使用调试工具
echo "=== 调试工具演示 ===\n";

// 开始调试
Debugger::start();
Debugger::checkpoint('开始执行');

// 模拟一些操作
Profiler::start('database_operation');
usleep(10000); // 模拟数据库操作
Debugger::logQuery('SELECT * FROM users WHERE id = ?', [123], 0.01);
Profiler::increment('db_queries');
$dbTime = Profiler::end('database_operation');

Debugger::checkpoint('数据库操作完成');

// 模拟更多操作
Profiler::start('file_operation');
$data = ['test' => 'data', 'numbers' => range(1, 1000)];
Debugger::dump($data, '测试数据');
usleep(5000); // 模拟文件操作
Profiler::increment('file_operations');
$fileTime = Profiler::end('file_operation');

Debugger::checkpoint('文件操作完成');

// 输出性能统计
echo "数据库操作耗时：" . number_format($dbTime * 1000, 2) . " ms\n";
echo "文件操作耗时：" . number_format($fileTime * 1000, 2) . " ms\n";
echo "数据库查询次数：" . Profiler::getCounter('db_queries') . "\n";
echo "文件操作次数：" . Profiler::getCounter('file_operations') . "\n";

// 生成调试报告
Debugger::report();
?>

8.3.3 Xdebug调试工具

<?php
// Xdebug调试演示
echo "=== Xdebug调试工具 ===\n";

// 检查Xdebug是否安装
if (extension_loaded('xdebug')) {
    echo "Xdebug已安装，版本：" . phpversion('xdebug') . "\n";
    
    // 显示Xdebug配置
    echo "\n--- Xdebug配置 ---\n";
    $xdebugSettings = [
        'xdebug.mode',
        'xdebug.start_with_request',
        'xdebug.client_host',
        'xdebug.client_port',
        'xdebug.log',
        'xdebug.var_display_max_depth',
        'xdebug.var_display_max_children',
        'xdebug.var_display_max_data'
    ];
    
    foreach ($xdebugSettings as $setting) {
        $value = ini_get($setting);
        echo "$setting: " . ($value !== false ? $value : '未设置') . "\n";
    }
    
    // 函数调用追踪
    echo "\n--- 函数调用追踪 ---\n";
    
    function traceDemo1() {
        traceDemo2();
    }
    
    function traceDemo2() {
        traceDemo3();
    }
    
    function traceDemo3() {
        // 使用xdebug_get_function_stack()获取调用栈
        if (function_exists('xdebug_get_function_stack')) {
            $stack = xdebug_get_function_stack();
            foreach ($stack as $frame) {
                echo "调用：{$frame['function']}() 在 {$frame['file']}:{$frame['line']}\n";
            }
        }
    }
    
    traceDemo1();
    
    // 变量显示
    echo "\n--- 变量显示增强 ---\n";
    $complexVar = [
        'user' => [
            'id' => 1,
            'name' => '张三',
            'profile' => [
                'age' => 25,
                'hobbies' => ['读书', '游泳', '编程']
            ]
        ],
        'settings' => [
            'theme' => 'dark',
            'language' => 'zh-CN'
        ]
    ];
    
    // Xdebug增强的var_dump输出
    var_dump($complexVar);
    
} else {
    echo "Xdebug未安装\n";
    echo "\n安装Xdebug的步骤：\n";
    echo "1. 访问 https://xdebug.org/wizard\n";
    echo "2. 粘贴 phpinfo() 输出\n";
    echo "3. 按照指示下载并安装对应版本\n";
    echo "4. 在php.ini中添加配置\n";
    
    echo "\n推荐的Xdebug配置：\n";
    echo "[xdebug]\n";
    echo "zend_extension=xdebug\n";
    echo "xdebug.mode=debug,develop\n";
    echo "xdebug.start_with_request=yes\n";
    echo "xdebug.client_host=127.0.0.1\n";
    echo "xdebug.client_port=9003\n";
    echo "xdebug.var_display_max_depth=3\n";
    echo "xdebug.var_display_max_children=128\n";
    echo "xdebug.var_display_max_data=512\n";
}
?>

8.4 日志记录

8.4.1 PHP内置日志功能

<?php
// PHP内置日志功能
echo "=== PHP内置日志功能 ===\n";

// 1. error_log() 函数
echo "--- error_log函数演示 ---\n";

// 记录到系统日志
error_log("这是一条系统日志消息");

// 记录到指定文件
$logFile = 'app.log';
error_log("这是一条应用日志消息", 3, $logFile);

// 发送邮件日志（需要配置邮件服务器）
// error_log("严重错误发生", 1, "admin@example.com");

// 记录到远程系统
// error_log("远程日志消息", 3, "tcp://logserver:514");

// 2. syslog() 函数
echo "\n--- syslog函数演示 ---\n";

// 打开系统日志
openlog("MyApp", LOG_PID | LOG_PERROR, LOG_LOCAL0);

// 记录不同级别的日志
syslog(LOG_INFO, "应用启动");
syslog(LOG_WARNING, "这是一个警告");
syslog(LOG_ERR, "这是一个错误");
syslog(LOG_DEBUG, "调试信息");

// 关闭系统日志
closelog();

// 3. 自定义日志函数
function writeLog($level, $message, $context = []) {
    $timestamp = date('Y-m-d H:i:s');
    $contextStr = !empty($context) ? ' ' . json_encode($context) : '';
    $logEntry = "[$timestamp] $level: $message$contextStr" . PHP_EOL;
    
    file_put_contents('custom.log', $logEntry, FILE_APPEND | LOCK_EX);
}

// 使用自定义日志函数
writeLog('INFO', '用户登录', ['user_id' => 123, 'ip' => '192.168.1.1']);
writeLog('ERROR', '数据库连接失败', ['error' => 'Connection timeout']);
writeLog('DEBUG', '查询执行', ['sql' => 'SELECT * FROM users', 'time' => 0.05]);

echo "日志已写入文件\n";
?>

8.4.2 PSR-3日志接口实现

<?php
// PSR-3日志接口实现
echo "=== PSR-3日志接口实现 ===\n";

// PSR-3 LoggerInterface接口
interface LoggerInterface {
    public function emergency($message, array $context = []);
    public function alert($message, array $context = []);
    public function critical($message, array $context = []);
    public function error($message, array $context = []);
    public function warning($message, array $context = []);
    public function notice($message, array $context = []);
    public function info($message, array $context = []);
    public function debug($message, array $context = []);
    public function log($level, $message, array $context = []);
}

// 日志级别常量
class LogLevel {
    const EMERGENCY = 'emergency';
    const ALERT     = 'alert';
    const CRITICAL  = 'critical';
    const ERROR     = 'error';
    const WARNING   = 'warning';
    const NOTICE    = 'notice';
    const INFO      = 'info';
    const DEBUG     = 'debug';
}

// 简单的日志实现
class SimpleLogger implements LoggerInterface {
    private $logFile;
    private $minLevel;
    private $levels = [
        LogLevel::EMERGENCY => 0,
        LogLevel::ALERT     => 1,
        LogLevel::CRITICAL  => 2,
        LogLevel::ERROR     => 3,
        LogLevel::WARNING   => 4,
        LogLevel::NOTICE    => 5,
        LogLevel::INFO      => 6,
        LogLevel::DEBUG     => 7
    ];
    
    public function __construct($logFile = 'app.log', $minLevel = LogLevel::DEBUG) {
        $this->logFile = $logFile;
        $this->minLevel = $minLevel;
    }
    
    public function emergency($message, array $context = []) {
        $this->log(LogLevel::EMERGENCY, $message, $context);
    }
    
    public function alert($message, array $context = []) {
        $this->log(LogLevel::ALERT, $message, $context);
    }
    
    public function critical($message, array $context = []) {
        $this->log(LogLevel::CRITICAL, $message, $context);
    }
    
    public function error($message, array $context = []) {
        $this->log(LogLevel::ERROR, $message, $context);
    }
    
    public function warning($message, array $context = []) {
        $this->log(LogLevel::WARNING, $message, $context);
    }
    
    public function notice($message, array $context = []) {
        $this->log(LogLevel::NOTICE, $message, $context);
    }
    
    public function info($message, array $context = []) {
        $this->log(LogLevel::INFO, $message, $context);
    }
    
    public function debug($message, array $context = []) {
        $this->log(LogLevel::DEBUG, $message, $context);
    }
    
    public function log($level, $message, array $context = []) {
        // 检查日志级别
        if ($this->levels[$level] > $this->levels[$this->minLevel]) {
            return;
        }
        
        // 插值处理
        $message = $this->interpolate($message, $context);
        
        // 格式化日志条目
        $logEntry = $this->formatLogEntry($level, $message, $context);
        
        // 写入日志文件
        file_put_contents($this->logFile, $logEntry, FILE_APPEND | LOCK_EX);
    }
    
    /**
     * 插值处理 - 替换消息中的占位符
     */
    private function interpolate($message, array $context) {
        $replace = [];
        foreach ($context as $key => $val) {
            if (!is_array($val) && (!is_object($val) || method_exists($val, '__toString'))) {
                $replace['{' . $key . '}'] = $val;
            }
        }
        
        return strtr($message, $replace);
    }
    
    /**
     * 格式化日志条目
     */
    private function formatLogEntry($level, $message, array $context) {
        $timestamp = date('Y-m-d H:i:s');
        $levelUpper = strtoupper($level);
        
        $logEntry = "[$timestamp] $levelUpper: $message";
        
        if (!empty($context)) {
            $logEntry .= ' ' . json_encode($context, JSON_UNESCAPED_UNICODE);
        }
        
        return $logEntry . PHP_EOL;
    }
}

// 多处理器日志记录器
class MultiLogger implements LoggerInterface {
    private $loggers = [];
    
    public function addLogger(LoggerInterface $logger) {
        $this->loggers[] = $logger;
    }
    
    public function emergency($message, array $context = []) {
        $this->log(LogLevel::EMERGENCY, $message, $context);
    }
    
    public function alert($message, array $context = []) {
        $this->log(LogLevel::ALERT, $message, $context);
    }
    
    public function critical($message, array $context = []) {
        $this->log(LogLevel::CRITICAL, $message, $context);
    }
    
    public function error($message, array $context = []) {
        $this->log(LogLevel::ERROR, $message, $context);
    }
    
    public function warning($message, array $context = []) {
        $this->log(LogLevel::WARNING, $message, $context);
    }
    
    public function notice($message, array $context = []) {
        $this->log(LogLevel::NOTICE, $message, $context);
    }
    
    public function info($message, array $context = []) {
        $this->log(LogLevel::INFO, $message, $context);
    }
    
    public function debug($message, array $context = []) {
        $this->log(LogLevel::DEBUG, $message, $context);
    }
    
    public function log($level, $message, array $context = []) {
        foreach ($this->loggers as $logger) {
            $logger->log($level, $message, $context);
        }
    }
}

// 使用日志记录器
echo "--- 使用PSR-3日志记录器 ---\n";

// 创建不同级别的日志记录器
$debugLogger = new SimpleLogger('debug.log', LogLevel::DEBUG);
$errorLogger = new SimpleLogger('error.log', LogLevel::ERROR);

// 创建多处理器日志记录器
$multiLogger = new MultiLogger();
$multiLogger->addLogger($debugLogger);
$multiLogger->addLogger($errorLogger);

// 记录不同级别的日志
$multiLogger->info('应用启动', ['version' => '1.0.0']);
$multiLogger->debug('调试信息', ['user_id' => 123]);
$multiLogger->warning('配置文件缺失', ['file' => 'config.ini']);
$multiLogger->error('数据库连接失败', ['host' => 'localhost', 'error' => 'Connection refused']);
$multiLogger->critical('系统内存不足', ['available' => '10MB', 'required' => '100MB']);

// 使用插值
$multiLogger->info('用户 {username} 从 {ip} 登录', [
    'username' => '张三',
    'ip' => '192.168.1.100',
    'user_id' => 123
]);

echo "日志记录完成\n";
?>

8.4.3 高级日志功能

<?php
// 高级日志功能
echo "=== 高级日志功能 ===\n";

// 日志轮转类
class RotatingLogger implements LoggerInterface {
    private $basePath;
    private $maxFiles;
    private $maxSize;
    private $minLevel;
    private $levels = [
        LogLevel::EMERGENCY => 0,
        LogLevel::ALERT     => 1,
        LogLevel::CRITICAL  => 2,
        LogLevel::ERROR     => 3,
        LogLevel::WARNING   => 4,
        LogLevel::NOTICE    => 5,
        LogLevel::INFO      => 6,
        LogLevel::DEBUG     => 7
    ];
    
    public function __construct($basePath = 'app.log', $maxFiles = 5, $maxSize = 1048576, $minLevel = LogLevel::DEBUG) {
        $this->basePath = $basePath;
        $this->maxFiles = $maxFiles;
        $this->maxSize = $maxSize;
        $this->minLevel = $minLevel;
    }
    
    public function emergency($message, array $context = []) {
        $this->log(LogLevel::EMERGENCY, $message, $context);
    }
    
    public function alert($message, array $context = []) {
        $this->log(LogLevel::ALERT, $message, $context);
    }
    
    public function critical($message, array $context = []) {
        $this->log(LogLevel::CRITICAL, $message, $context);
    }
    
    public function error($message, array $context = []) {
        $this->log(LogLevel::ERROR, $message, $context);
    }
    
    public function warning($message, array $context = []) {
        $this->log(LogLevel::WARNING, $message, $context);
    }
    
    public function notice($message, array $context = []) {
        $this->log(LogLevel::NOTICE, $message, $context);
    }
    
    public function info($message, array $context = []) {
        $this->log(LogLevel::INFO, $message, $context);
    }
    
    public function debug($message, array $context = []) {
        $this->log(LogLevel::DEBUG, $message, $context);
    }
    
    public function log($level, $message, array $context = []) {
        if ($this->levels[$level] > $this->levels[$this->minLevel]) {
            return;
        }
        
        $currentLogFile = $this->getCurrentLogFile();
        
        // 检查是否需要轮转
        if (file_exists($currentLogFile) && filesize($currentLogFile) >= $this->maxSize) {
            $this->rotateLogFiles();
        }
        
        // 格式化并写入日志
        $logEntry = $this->formatLogEntry($level, $message, $context);
        file_put_contents($currentLogFile, $logEntry, FILE_APPEND | LOCK_EX);
    }
    
    private function getCurrentLogFile() {
        return $this->basePath;
    }
    
    private function rotateLogFiles() {
        // 删除最旧的日志文件
        $oldestFile = $this->basePath . '.' . $this->maxFiles;
        if (file_exists($oldestFile)) {
            unlink($oldestFile);
        }
        
        // 重命名现有日志文件
        for ($i = $this->maxFiles - 1; $i >= 1; $i--) {
            $oldFile = $this->basePath . '.' . $i;
            $newFile = $this->basePath . '.' . ($i + 1);
            
            if (file_exists($oldFile)) {
                rename($oldFile, $newFile);
            }
        }
        
        // 重命名当前日志文件
        if (file_exists($this->basePath)) {
            rename($this->basePath, $this->basePath . '.1');
        }
    }
    
    private function formatLogEntry($level, $message, array $context) {
        $timestamp = date('Y-m-d H:i:s');
        $levelUpper = strtoupper($level);
        $pid = getmypid();
        $memory = memory_get_usage(true);
        
        // 插值处理
        $replace = [];
        foreach ($context as $key => $val) {
            if (!is_array($val) && (!is_object($val) || method_exists($val, '__toString'))) {
                $replace['{' . $key . '}'] = $val;
            }
        }
        $message = strtr($message, $replace);
        
        $logEntry = "[$timestamp] [$pid] [$memory] $levelUpper: $message";
        
        if (!empty($context)) {
            $logEntry .= ' ' . json_encode($context, JSON_UNESCAPED_UNICODE);
        }
        
        return $logEntry . PHP_EOL;
    }
}

// 结构化日志记录器
class StructuredLogger implements LoggerInterface {
    private $logFile;
    private $minLevel;
    private $levels = [
        LogLevel::EMERGENCY => 0,
        LogLevel::ALERT     => 1,
        LogLevel::CRITICAL  => 2,
        LogLevel::ERROR     => 3,
        LogLevel::WARNING   => 4,
        LogLevel::NOTICE    => 5,
        LogLevel::INFO      => 6,
        LogLevel::DEBUG     => 7
    ];
    
    public function __construct($logFile = 'structured.log', $minLevel = LogLevel::DEBUG) {
        $this->logFile = $logFile;
        $this->minLevel = $minLevel;
    }
    
    public function emergency($message, array $context = []) {
        $this->log(LogLevel::EMERGENCY, $message, $context);
    }
    
    public function alert($message, array $context = []) {
        $this->log(LogLevel::ALERT, $message, $context);
    }
    
    public function critical($message, array $context = []) {
        $this->log(LogLevel::CRITICAL, $message, $context);
    }
    
    public function error($message, array $context = []) {
        $this->log(LogLevel::ERROR, $message, $context);
    }
    
    public function warning($message, array $context = []) {
        $this->log(LogLevel::WARNING, $message, $context);
    }
    
    public function notice($message, array $context = []) {
        $this->log(LogLevel::NOTICE, $message, $context);
    }
    
    public function info($message, array $context = []) {
        $this->log(LogLevel::INFO, $message, $context);
    }
    
    public function debug($message, array $context = []) {
        $this->log(LogLevel::DEBUG, $message, $context);
    }
    
    public function log($level, $message, array $context = []) {
        if ($this->levels[$level] > $this->levels[$this->minLevel]) {
            return;
        }
        
        // 创建结构化日志条目
        $logEntry = [
            'timestamp' => date('c'), // ISO 8601格式
            'level' => $level,
            'message' => $message,
            'context' => $context,
            'extra' => [
                'process_id' => getmypid(),
                'memory_usage' => memory_get_usage(true),
                'peak_memory' => memory_get_peak_usage(true),
                'execution_time' => microtime(true) - $_SERVER['REQUEST_TIME_FLOAT']
            ]
        ];
        
        // 添加请求信息（如果在Web环境中）
        if (isset($_SERVER['REQUEST_METHOD'])) {
            $logEntry['request'] = [
                'method' => $_SERVER['REQUEST_METHOD'],
                'uri' => $_SERVER['REQUEST_URI'] ?? '',
                'user_agent' => $_SERVER['HTTP_USER_AGENT'] ?? '',
                'ip' => $_SERVER['REMOTE_ADDR'] ?? ''
            ];
        }
        
        // 写入JSON格式的日志
        $jsonLog = json_encode($logEntry, JSON_UNESCAPED_UNICODE) . PHP_EOL;
        file_put_contents($this->logFile, $jsonLog, FILE_APPEND | LOCK_EX);
    }
}

// 使用高级日志功能
echo "--- 使用轮转日志记录器 ---\n";
$rotatingLogger = new RotatingLogger('rotating.log', 3, 1024); // 1KB轮转

for ($i = 1; $i <= 10; $i++) {
    $rotatingLogger->info("这是第 $i 条日志消息", ['iteration' => $i]);
    $rotatingLogger->debug("调试信息 $i", ['data' => str_repeat('x', 100)]);
}

echo "--- 使用结构化日志记录器 ---\n";
$structuredLogger = new StructuredLogger('structured.log');

$structuredLogger->info('用户登录', [
    'user_id' => 123,
    'username' => '张三',
    'login_method' => 'password'
]);

$structuredLogger->error('支付失败', [
    'order_id' => 'ORD-12345',
    'amount' => 99.99,
    'currency' => 'CNY',
    'error_code' => 'INSUFFICIENT_FUNDS'
]);

$structuredLogger->warning('API调用频率过高', [
    'api_key' => 'key_123',
    'endpoint' => '/api/users',
    'rate_limit' => 100,
    'current_count' => 95
]);

echo "高级日志记录完成\n";
?>

8.5 最佳实践

8.5.1 错误处理最佳实践

<?php
// 错误处理最佳实践
echo "=== 错误处理最佳实践 ===\n";

// 1. 使用适当的异常类型
class ValidationException extends Exception {
    private $errors;
    
    public function __construct($message, array $errors = [], $code = 0, Exception $previous = null) {
        parent::__construct($message, $code, $previous);
        $this->errors = $errors;
    }
    
    public function getErrors() {
        return $this->errors;
    }
}

class BusinessLogicException extends Exception {}
class ExternalServiceException extends Exception {}

// 2. 分层异常处理
class DataLayer {
    public function findUser($id) {
        if ($id <= 0) {
            throw new InvalidArgumentException('用户ID必须大于0');
        }
        
        // 模拟数据库查询失败
        if ($id === 999) {
            throw new RuntimeException('数据库连接失败');
        }
        
        // 模拟用户不存在
        if ($id === 404) {
            return null;
        }
        
        return ['id' => $id, 'name' => '用户' . $id];
    }
}

class BusinessLayer {
    private $dataLayer;
    
    public function __construct(DataLayer $dataLayer) {
        $this->dataLayer = $dataLayer;
    }
    
    public function getUser($id) {
        try {
            $user = $this->dataLayer->findUser($id);
            
            if ($user === null) {
                throw new BusinessLogicException("用户 $id 不存在");
            }
            
            return $user;
        } catch (InvalidArgumentException $e) {
            // 参数验证错误，重新抛出
            throw new ValidationException('参数验证失败', ['id' => $e->getMessage()]);
        } catch (RuntimeException $e) {
            // 数据层错误，包装后重新抛出
            throw new ExternalServiceException('数据服务不可用', 503, $e);
        }
    }
}

class PresentationLayer {
    private $businessLayer;
    private $logger;
    
    public function __construct(BusinessLayer $businessLayer, LoggerInterface $logger) {
        $this->businessLayer = $businessLayer;
        $this->logger = $logger;
    }
    
    public function handleUserRequest($id) {
        try {
            $user = $this->businessLayer->getUser($id);
            
            $this->logger->info('用户查询成功', ['user_id' => $id]);
            
            return [
                'success' => true,
                'data' => $user
            ];
        } catch (ValidationException $e) {
            $this->logger->warning('用户请求验证失败', [
                'user_id' => $id,
                'errors' => $e->getErrors()
            ]);
            
            return [
                'success' => false,
                'error' => '请求参数无效',
                'details' => $e->getErrors(),
                'code' => 400
            ];
        } catch (BusinessLogicException $e) {
            $this->logger->info('业务逻辑异常', [
                'user_id' => $id,
                'message' => $e->getMessage()
            ]);
            
            return [
                'success' => false,
                'error' => $e->getMessage(),
                'code' => 404
            ];
        } catch (ExternalServiceException $e) {
            $this->logger->error('外部服务异常', [
                'user_id' => $id,
                'message' => $e->getMessage(),
                'previous' => $e->getPrevious() ? $e->getPrevious()->getMessage() : null
            ]);
            
            return [
                'success' => false,
                'error' => '服务暂时不可用，请稍后重试',
                'code' => 503
            ];
        } catch (Exception $e) {
            // 未预期的异常
            $this->logger->critical('未处理的异常', [
                'user_id' => $id,
                'exception' => get_class($e),
                'message' => $e->getMessage(),
                'file' => $e->getFile(),
                'line' => $e->getLine()
            ]);
            
            return [
                'success' => false,
                'error' => '系统内部错误',
                'code' => 500
            ];
        }
    }
}

// 3. 优雅降级
class ServiceWithFallback {
    private $primaryService;
    private $fallbackService;
    private $logger;
    
    public function __construct($primaryService, $fallbackService, LoggerInterface $logger) {
        $this->primaryService = $primaryService;
        $this->fallbackService = $fallbackService;
        $this->logger = $logger;
    }
    
    public function getData($id) {
        try {
            return $this->primaryService->getData($id);
        } catch (Exception $e) {
            $this->logger->warning('主服务失败，使用备用服务', [
                'primary_error' => $e->getMessage(),
                'id' => $id
            ]);
            
            try {
                return $this->fallbackService->getData($id);
            } catch (Exception $fallbackError) {
                $this->logger->error('备用服务也失败', [
                    'primary_error' => $e->getMessage(),
                    'fallback_error' => $fallbackError->getMessage(),
                    'id' => $id
                ]);
                
                // 返回默认值或缓存数据
                return $this->getDefaultData($id);
            }
        }
    }
    
    private function getDefaultData($id) {
        return ['id' => $id, 'data' => '默认数据', 'source' => 'fallback'];
    }
}

// 4. 重试机制
class RetryableService {
    private $maxRetries;
    private $retryDelay;
    private $logger;
    
    public function __construct($maxRetries = 3, $retryDelay = 1000, LoggerInterface $logger = null) {
        $this->maxRetries = $maxRetries;
        $this->retryDelay = $retryDelay;
        $this->logger = $logger;
    }
    
    public function callExternalAPI($url) {
        $attempt = 0;
        
        while ($attempt < $this->maxRetries) {
            try {
                $attempt++;
                
                // 模拟API调用
                if (rand(1, 3) === 1) { // 33%成功率
                    return ['status' => 'success', 'data' => 'API响应数据'];
                } else {
                    throw new RuntimeException('API调用失败');
                }
            } catch (Exception $e) {
                if ($this->logger) {
                    $this->logger->warning('API调用失败', [
                        'attempt' => $attempt,
                        'max_retries' => $this->maxRetries,
                        'url' => $url,
                        'error' => $e->getMessage()
                    ]);
                }
                
                if ($attempt >= $this->maxRetries) {
                    throw new ExternalServiceException(
                        "API调用在 {$this->maxRetries} 次重试后仍然失败",
                        0,
                        $e
                    );
                }
                
                // 等待后重试
                usleep($this->retryDelay * 1000);
            }
        }
    }
}

// 测试最佳实践
echo "--- 测试分层异常处理 ---\n";
$logger = new SimpleLogger('best_practices.log');
$dataLayer = new DataLayer();
$businessLayer = new BusinessLayer($dataLayer);
$presentationLayer = new PresentationLayer($businessLayer, $logger);

// 测试不同场景
$testCases = [1, -1, 404, 999];
foreach ($testCases as $id) {
    echo "测试用户ID: $id\n";
    $result = $presentationLayer->handleUserRequest($id);
    echo "结果: " . json_encode($result, JSON_UNESCAPED_UNICODE) . "\n\n";
}

echo "--- 测试重试机制 ---\n";
$retryService = new RetryableService(3, 500, $logger);

try {
    $result = $retryService->callExternalAPI('https://api.example.com/data');
    echo "API调用成功: " . json_encode($result) . "\n";
} catch (ExternalServiceException $e) {
    echo "API调用最终失败: " . $e->getMessage() . "\n";
}

echo "最佳实践演示完成\n";
?>

8.5.2 生产环境配置

<?php
// 生产环境错误处理配置
echo "=== 生产环境配置 ===\n";

// 生产环境错误处理器
class ProductionErrorHandler {
    private $logger;
    private $notifier;
    
    public function __construct(LoggerInterface $logger, $notifier = null) {
        $this->logger = $logger;
        $this->notifier = $notifier;
        
        $this->setupErrorHandling();
    }
    
    private function setupErrorHandling() {
        // 关闭错误显示
        ini_set('display_errors', 0);
        ini_set('display_startup_errors', 0);
        
        // 启用错误日志
        ini_set('log_errors', 1);
        ini_set('error_log', 'php_errors.log');
        
        // 设置错误报告级别
        error_reporting(E_ALL & ~E_NOTICE & ~E_STRICT & ~E_DEPRECATED);
        
        // 注册处理器
        set_error_handler([$this, 'handleError']);
        set_exception_handler([$this, 'handleException']);
        register_shutdown_function([$this, 'handleShutdown']);
    }
    
    public function handleError($errno, $errstr, $errfile, $errline) {
        // 忽略被@抑制的错误
        if (!(error_reporting() & $errno)) {
            return false;
        }
        
        $errorInfo = [
            'type' => $this->getErrorType($errno),
            'message' => $errstr,
            'file' => $errfile,
            'line' => $errline,
            'severity' => $errno
        ];
        
        $this->logError($errorInfo);
        
        // 严重错误需要通知
        if ($errno & (E_ERROR | E_USER_ERROR | E_RECOVERABLE_ERROR)) {
            $this->notifyError($errorInfo);
        }
        
        return true;
    }
    
    public function handleException($exception) {
        $errorInfo = [
            'type' => 'Uncaught Exception',
            'class' => get_class($exception),
            'message' => $exception->getMessage(),
            'file' => $exception->getFile(),
            'line' => $exception->getLine(),
            'trace' => $exception->getTraceAsString()
        ];
        
        $this->logError($errorInfo);
        $this->notifyError($errorInfo);
        
        // 显示友好的错误页面
        $this->showErrorPage();
    }
    
    public function handleShutdown() {
        $error = error_get_last();
        
        if ($error && in_array($error['type'], [E_ERROR, E_PARSE, E_CORE_ERROR, E_COMPILE_ERROR])) {
            $errorInfo = [
                'type' => 'Fatal Error',
                'message' => $error['message'],
                'file' => $error['file'],
                'line' => $error['line']
            ];
            
            $this->logError($errorInfo);
            $this->notifyError($errorInfo);
        }
    }
    
    private function logError($errorInfo) {
        $this->logger->error('PHP Error: ' . $errorInfo['message'], $errorInfo);
    }
    
    private function notifyError($errorInfo) {
        if ($this->notifier) {
            $this->notifier->notify($errorInfo);
        }
    }
    
    private function showErrorPage() {
        if (!headers_sent()) {
            http_response_code(500);
            header('Content-Type: text/html; charset=utf-8');
        }
        
        echo '<!DOCTYPE html>
<html>
<head>
    <title>服务暂时不可用</title>
    <style>
        body { font-family: Arial, sans-serif; text-align: center; padding: 50px; }
        .error-container { max-width: 500px; margin: 0 auto; }
        h1 { color: #e74c3c; }
    </style>
</head>
<body>
    <div class="error-container">
        <h1>服务暂时不可用</h1>
        <p>我们正在努力解决这个问题，请稍后再试。</p>
        <p>如果问题持续存在，请联系技术支持。</p>
    </div>
</body>
</html>';
        
        exit(1);
    }
    
    private function getErrorType($errno) {
        $errorTypes = [
            E_ERROR => 'Fatal Error',
            E_WARNING => 'Warning',
            E_NOTICE => 'Notice',
            E_USER_ERROR => 'User Error',
            E_USER_WARNING => 'User Warning',
            E_USER_NOTICE => 'User Notice',
            E_STRICT => 'Strict Standards',
            E_RECOVERABLE_ERROR => 'Recoverable Error',
            E_DEPRECATED => 'Deprecated',
            E_USER_DEPRECATED => 'User Deprecated'
        ];
        
        return isset($errorTypes[$errno]) ? $errorTypes[$errno] : 'Unknown Error';
    }
}

// 错误通知器
class ErrorNotifier {
    private $webhookUrl;
    private $emailRecipients;
    
    public function __construct($webhookUrl = null, array $emailRecipients = []) {
        $this->webhookUrl = $webhookUrl;
        $this->emailRecipients = $emailRecipients;
    }
    
    public function notify($errorInfo) {
        // 发送到Webhook（如Slack、钉钉等）
        if ($this->webhookUrl) {
            $this->sendWebhook($errorInfo);
        }
        
        // 发送邮件通知
        if (!empty($this->emailRecipients)) {
            $this->sendEmail($errorInfo);
        }
    }
    
    private function sendWebhook($errorInfo) {
        $payload = [
            'text' => '🚨 生产环境错误警报',
            'attachments' => [
                [
                    'color' => 'danger',
                    'fields' => [
                        [
                            'title' => '错误类型',
                            'value' => $errorInfo['type'],
                            'short' => true
                        ],
                        [
                            'title' => '错误消息',
                            'value' => $errorInfo['message'],
                            'short' => false
                        ],
                        [
                            'title' => '文件位置',
                            'value' => $errorInfo['file'] . ':' . $errorInfo['line'],
                            'short' => true
                        ],
                        [
                            'title' => '时间',
                            'value' => date('Y-m-d H:i:s'),
                            'short' => true
                        ]
                    ]
                ]
            ]
        ];
        
        // 模拟发送Webhook
        echo "发送Webhook通知: " . json_encode($payload, JSON_UNESCAPED_UNICODE) . "\n";
    }
    
    private function sendEmail($errorInfo) {
        $subject = '[生产环境] 错误警报: ' . $errorInfo['type'];
        $message = "错误详情:\n\n";
        $message .= "类型: {$errorInfo['type']}\n";
        $message .= "消息: {$errorInfo['message']}\n";
        $message .= "文件: {$errorInfo['file']}\n";
        $message .= "行号: {$errorInfo['line']}\n";
        $message .= "时间: " . date('Y-m-d H:i:s') . "\n";
        
        if (isset($errorInfo['trace'])) {
            $message .= "\n调用栈:\n{$errorInfo['trace']}\n";
        }
        
        // 模拟发送邮件
        foreach ($this->emailRecipients as $email) {
            echo "发送邮件到 $email: $subject\n";
        }
    }
}

// 健康检查
class HealthChecker {
    private $checks = [];
    
    public function addCheck($name, callable $check) {
        $this->checks[$name] = $check;
    }
    
    public function runChecks() {
        $results = [];
        $overallStatus = 'healthy';
        
        foreach ($this->checks as $name => $check) {
            try {
                $startTime = microtime(true);
                $result = call_user_func($check);
                $duration = microtime(true) - $startTime;
                
                $results[$name] = [
                    'status' => $result ? 'healthy' : 'unhealthy',
                    'duration' => round($duration * 1000, 2) . 'ms'
                ];
                
                if (!$result) {
                    $overallStatus = 'unhealthy';
                }
            } catch (Exception $e) {
                $results[$name] = [
                    'status' => 'error',
                    'error' => $e->getMessage()
                ];
                $overallStatus = 'unhealthy';
            }
        }
        
        return [
            'status' => $overallStatus,
            'timestamp' => date('c'),
            'checks' => $results
        ];
    }
}

// 使用生产环境配置
echo "--- 生产环境配置演示 ---\n";

$logger = new SimpleLogger('production.log');
$notifier = new ErrorNotifier(
    'https://hooks.slack.com/services/xxx',
    ['admin@example.com', 'dev@example.com']
);

$errorHandler = new ProductionErrorHandler($logger, $notifier);

// 健康检查示例
$healthChecker = new HealthChecker();

$healthChecker->addCheck('database', function() {
    // 模拟数据库连接检查
    return rand(0, 1) === 1;
});

$healthChecker->addCheck('redis', function() {
    // 模拟Redis连接检查
    return true;
});

$healthChecker->addCheck('external_api', function() {
    // 模拟外部API检查
    if (rand(0, 1) === 0) {
        throw new Exception('API连接超时');
    }
    return true;
});

$healthStatus = $healthChecker->runChecks();
echo "健康检查结果: " . json_encode($healthStatus, JSON_UNESCAPED_UNICODE | JSON_PRETTY_PRINT) . "\n";

echo "生产环境配置完成\n";
?>

8.6 小结

本章详细介绍了PHP中的错误处理与异常机制，主要内容包括：

核心概念

错误类型：Fatal Error、Warning、Notice、Parse Error等
异常处理：try-catch-finally结构、异常传播、自定义异常
调试技巧：调试函数、Xdebug工具、性能分析
日志记录：PSR-3标准、结构化日志、日志轮转

最佳实践

分层异常处理：在不同层次处理不同类型的异常
优雅降级：提供备用方案和默认值
重试机制：对临时性错误进行重试
生产环境配置：关闭错误显示、启用日志记录、错误通知

实用工具

自定义错误处理器：统一处理各种错误和异常
日志记录器：支持多种格式和输出方式
调试工具类：性能分析、内存监控
健康检查：监控系统各组件状态

8.7 实践练习

创建异常处理系统
- 设计自定义异常类层次结构
- 实现统一的异常处理机制
- 添加日志记录和错误通知
开发调试工具
- 创建性能分析器
- 实现SQL查询监控
- 添加内存使用追踪
构建日志系统
- 实现PSR-3兼容的日志记录器
- 支持多种输出格式（文本、JSON、XML）
- 添加日志轮转和压缩功能
生产环境部署
- 配置错误处理和日志记录
- 设置监控和告警机制
- 实现健康检查端点

8.8 扩展阅读

下一章预告：第九章将介绍文件系统操作，包括文件读写、目录操作、文件上传、权限管理等内容。

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📚 第八章：错误处理与异常

8.1 PHP错误类型

8.1.1 错误级别

8.1.2 错误报告设置

8.1.3 错误处理最佳实践

8.2 异常处理机制

8.2.1 异常基础

8.2.2 异常传播和重新抛出

8.2.3 自定义异常类

8.3 调试技巧

8.3.1 调试函数和工具

8.3.2 调试类和工具

8.3.3 Xdebug调试工具

8.4 日志记录

8.4.1 PHP内置日志功能

8.4.2 PSR-3日志接口实现

8.4.3 高级日志功能

8.5 最佳实践

8.5.1 错误处理最佳实践

8.5.2 生产环境配置

8.6 小结

核心概念

最佳实践

实用工具

8.7 实践练习

8.8 扩展阅读

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