当前位置： 首页 > backend >正文

责任链框架 03：处理器实现

backend 2025/9/7 12:27:14

处理器实现

概述

处理器是责任链框架的核心组件，负责执行具体的业务逻辑。一个好的处理器实现应该遵循单一职责原则，具有清晰的处理逻辑和明确的终止条件。本章将详细介绍如何实现高质量的处理器。

处理器实现规范

1. 基本实现结构

«abstract»
AbstractHandler
+handle(Context context) : boolean
#doHandle(Context context)
#shouldSkip(Context context) : boolean
#onBefore(Context context) : void
#onAfter(Context context) : void
#onError(Context context, Exception e) : void
ConcreteHandler
+doHandle(Context context) : boolean
+shouldSkip(Context context) : boolean
-canHandle(Context context) : boolean
-processRequest(Context context) : void
-validateInput(Context context) : boolean

2. 处理器实现模板

/*** 处理器实现模板* 展示了一个标准处理器的实现结构*/
public class TemplateHandler extends AbstractHandler<RequestType, ResponseType> {private static final Logger logger = LoggerFactory.getLogger(TemplateHandler.class);@Overrideprotected boolean doHandle(Context<RequestType, ResponseType> context) {// 1. 输入验证if (!validateInput(context)) {logger.warn("Input validation failed in {}", this.getClass().getSimpleName());return false; // 验证失败，中断链}// 2. 检查是否能处理该请求if (!canHandle(context)) {logger.debug("Cannot handle request in {}", this.getClass().getSimpleName());return true; // 不能处理，传递给下一个处理器}// 3. 执行具体的处理逻辑try {processRequest(context);logger.info("Request processed successfully in {}", this.getClass().getSimpleName());return true; // 处理成功，继续传递} catch (BusinessException e) {logger.error("Business error in {}: {}", this.getClass().getSimpleName(), e.getMessage());handleBusinessError(context, e);return false; // 业务异常，中断链}}/*** 验证输入参数*/private boolean validateInput(Context<RequestType, ResponseType> context) {RequestType request = context.getRequest();return request != null; // 简单的非空验证}/*** 判断是否能处理该请求*/private boolean canHandle(Context<RequestType, ResponseType> context) {// 根据请求类型、状态等判断是否能处理return true;}/*** 执行具体的处理逻辑*/private void processRequest(Context<RequestType, ResponseType> context) {// 具体的业务逻辑实现}/*** 处理业务异常*/private void handleBusinessError(Context<RequestType, ResponseType> context, BusinessException e) {// 设置错误响应ResponseType errorResponse = createErrorResponse(e.getMessage());context.setResponse(errorResponse);}private ResponseType createErrorResponse(String message) {// 创建错误响应对象return null;}
}

具体处理器实现示例

1. 认证处理器

/*** 用户认证处理器* 负责验证用户身份*/
@Component
public class AuthenticationHandler extends AbstractHandler<UserRequest, UserResponse> {private static final Logger logger = LoggerFactory.getLogger(AuthenticationHandler.class);@Autowiredprivate UserService userService;@Autowiredprivate TokenService tokenService;@Overrideprotected boolean doHandle(Context<UserRequest, UserResponse> context) {UserRequest request = context.getRequest();// 1. 检查是否已经认证过if (isAlreadyAuthenticated(context)) {logger.debug("User already authenticated, skipping authentication");return true;}// 2. 提取认证信息String token = extractToken(request);if (token == null) {logger.warn("No authentication token found");setAuthenticationError(context, "Missing authentication token");return false;}// 3. 验证tokentry {User user = tokenService.validateToken(token);if (user == null) {logger.warn("Invalid authentication token");setAuthenticationError(context, "Invalid authentication token");return false;}// 4. 设置认证信息到上下文context.setAttribute("authenticated_user", user);context.setAttribute("user_id", user.getId());context.setAttribute("user_roles", user.getRoles());logger.info("User {} authenticated successfully", user.getUsername());return true;} catch (TokenExpiredException e) {logger.warn("Authentication token expired");setAuthenticationError(context, "Authentication token expired");return false;} catch (Exception e) {logger.error("Authentication failed", e);setAuthenticationError(context, "Authentication failed");return false;}}@Overrideprotected boolean shouldSkip(Context<UserRequest, ResponseType> context) {// 如果是公开接口，跳过认证UserRequest request = context.getRequest();return request.isPublicEndpoint();}private boolean isAlreadyAuthenticated(Context<UserRequest, UserResponse> context) {return context.getAttribute("authenticated_user") != null;}private String extractToken(UserRequest request) {String authHeader = request.getHeader("Authorization");if (authHeader != null && authHeader.startsWith("Bearer ")) {return authHeader.substring(7);}return null;}private void setAuthenticationError(Context<UserRequest, UserResponse> context, String message) {UserResponse response = new UserResponse();response.setSuccess(false);response.setErrorCode("AUTH_FAILED");response.setErrorMessage(message);context.setResponse(response);}
}

2. 授权处理器

/*** 用户授权处理器* 负责检查用户权限*/
@Component
public class AuthorizationHandler extends AbstractHandler<UserRequest, UserResponse> {private static final Logger logger = LoggerFactory.getLogger(AuthorizationHandler.class);@Autowiredprivate PermissionService permissionService;@Overrideprotected boolean doHandle(Context<UserRequest, UserResponse> context) {// 1. 获取认证用户信息User user = context.getAttribute("authenticated_user", User.class);if (user == null) {logger.error("No authenticated user found, authorization cannot proceed");setAuthorizationError(context, "User not authenticated");return false;}// 2. 获取请求的资源和操作UserRequest request = context.getRequest();String resource = request.getResource();String action = request.getAction();// 3. 检查权限try {boolean hasPermission = permissionService.hasPermission(user, resource, action);if (!hasPermission) {logger.warn("User {} does not have permission to {} on {}", user.getUsername(), action, resource);setAuthorizationError(context, "Insufficient permissions");return false;}// 4. 记录权限信息context.setAttribute("authorized_resource", resource);context.setAttribute("authorized_action", action);logger.info("User {} authorized for {} on {}", user.getUsername(), action, resource);return true;} catch (Exception e) {logger.error("Authorization check failed", e);setAuthorizationError(context, "Authorization check failed");return false;}}@Overrideprotected boolean shouldSkip(Context<UserRequest, UserResponse> context) {// 如果是公开资源或者超级管理员，跳过授权检查UserRequest request = context.getRequest();if (request.isPublicResource()) {return true;}User user = context.getAttribute("authenticated_user", User.class);return user != null && user.isSuperAdmin();}private void setAuthorizationError(Context<UserRequest, UserResponse> context, String message) {UserResponse response = new UserResponse();response.setSuccess(false);response.setErrorCode("AUTH_INSUFFICIENT_PERMISSIONS");response.setErrorMessage(message);context.setResponse(response);}
}

3. 参数验证处理器

/*** 参数验证处理器* 负责验证请求参数的合法性*/
@Component
public class ValidationHandler extends AbstractHandler<UserRequest, UserResponse> {private static final Logger logger = LoggerFactory.getLogger(ValidationHandler.class);@Autowiredprivate Validator validator;@Overrideprotected boolean doHandle(Context<UserRequest, UserResponse> context) {UserRequest request = context.getRequest();// 1. 基本参数验证List<String> errors = new ArrayList<>();// 验证必填字段validateRequiredFields(request, errors);// 验证字段格式validateFieldFormats(request, errors);// 验证业务规则validateBusinessRules(request, errors);// 2. 使用Bean ValidationSet<ConstraintViolation<UserRequest>> violations = validator.validate(request);for (ConstraintViolation<UserRequest> violation : violations) {errors.add(violation.getMessage());}// 3. 检查验证结果if (!errors.isEmpty()) {logger.warn("Validation failed: {}", String.join(", ", errors));setValidationError(context, errors);return false;}logger.debug("Request validation passed");return true;}private void validateRequiredFields(UserRequest request, List<String> errors) {if (StringUtils.isBlank(request.getUserId())) {errors.add("User ID is required");}if (StringUtils.isBlank(request.getAction())) {errors.add("Action is required");}}private void validateFieldFormats(UserRequest request, List<String> errors) {// 验证邮箱格式if (request.getEmail() != null && !isValidEmail(request.getEmail())) {errors.add("Invalid email format");}// 验证手机号格式if (request.getPhone() != null && !isValidPhone(request.getPhone())) {errors.add("Invalid phone format");}}private void validateBusinessRules(UserRequest request, List<String> errors) {// 验证年龄范围if (request.getAge() != null && (request.getAge() < 0 || request.getAge() > 150)) {errors.add("Age must be between 0 and 150");}// 验证日期范围if (request.getBirthDate() != null && request.getBirthDate().isAfter(LocalDate.now())) {errors.add("Birth date cannot be in the future");}}private boolean isValidEmail(String email) {return email.matches("^[A-Za-z0-9+_.-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,}$");}private boolean isValidPhone(String phone) {return phone.matches("^1[3-9]\\d{9}$");}private void setValidationError(Context<UserRequest, UserResponse> context, List<String> errors) {UserResponse response = new UserResponse();response.setSuccess(false);response.setErrorCode("VALIDATION_FAILED");response.setErrorMessage("Validation failed: " + String.join(", ", errors));response.setValidationErrors(errors);context.setResponse(response);}
}

4. 业务逻辑处理器

/*** 业务逻辑处理器* 负责执行核心业务逻辑*/
@Component
public class BusinessLogicHandler extends AbstractHandler<UserRequest, UserResponse> {private static final Logger logger = LoggerFactory.getLogger(BusinessLogicHandler.class);@Autowiredprivate BusinessService businessService;@Autowiredprivate AuditService auditService;@Overrideprotected boolean doHandle(Context<UserRequest, UserResponse> context) {UserRequest request = context.getRequest();User user = context.getAttribute("authenticated_user", User.class);try {// 1. 记录审计日志auditService.logBusinessOperation(user, request);// 2. 执行业务逻辑BusinessResult result = businessService.processRequest(request, user);// 3. 构建响应UserResponse response = buildSuccessResponse(result);context.setResponse(response);// 4. 设置处理结果到上下文context.setAttribute("business_result", result);context.setAttribute("processing_time", System.currentTimeMillis());logger.info("Business logic processed successfully for user {}", user.getUsername());return true;} catch (BusinessException e) {logger.error("Business logic failed: {}", e.getMessage());setBusinessError(context, e);return false;} catch (Exception e) {logger.error("Unexpected error in business logic", e);setSystemError(context, e);return false;}}@Overrideprotected void onBefore(Context<UserRequest, UserResponse> context) {// 记录开始时间context.setAttribute("business_start_time", System.currentTimeMillis());}@Overrideprotected void onAfter(Context<UserRequest, UserResponse> context) {// 计算处理时间Long startTime = context.getAttribute("business_start_time", Long.class);if (startTime != null) {long duration = System.currentTimeMillis() - startTime;context.setAttribute("business_duration", duration);logger.debug("Business logic processing took {} ms", duration);}}@Overrideprotected void onError(Context<UserRequest, UserResponse> context, Exception e) {// 记录错误审计日志User user = context.getAttribute("authenticated_user", User.class);auditService.logBusinessError(user, context.getRequest(), e);}private UserResponse buildSuccessResponse(BusinessResult result) {UserResponse response = new UserResponse();response.setSuccess(true);response.setData(result.getData());response.setMessage("Operation completed successfully");return response;}private void setBusinessError(Context<UserRequest, UserResponse> context, BusinessException e) {UserResponse response = new UserResponse();response.setSuccess(false);response.setErrorCode(e.getErrorCode());response.setErrorMessage(e.getMessage());context.setResponse(response);}private void setSystemError(Context<UserRequest, UserResponse> context, Exception e) {UserResponse response = new UserResponse();response.setSuccess(false);response.setErrorCode("SYSTEM_ERROR");response.setErrorMessage("System error occurred");context.setResponse(response);}
}

处理逻辑实现要点

1. 输入验证

public class InputValidationExample {/*** 多层次输入验证*/private boolean validateInput(Context context) {// 1. 空值检查if (context.getRequest() == null) {return false;}// 2. 类型检查if (!(context.getRequest() instanceof ExpectedType)) {return false;}// 3. 业务规则验证return validateBusinessRules(context.getRequest());}/*** 使用断言进行验证*/private void validateWithAssertions(UserRequest request) {Assert.notNull(request, "Request cannot be null");Assert.hasText(request.getUserId(), "User ID cannot be empty");Assert.isTrue(request.getAge() >= 0, "Age cannot be negative");}
}

2. 异常处理策略

public class ExceptionHandlingExample {@Overrideprotected boolean doHandle(Context context) {try {return processRequest(context);} catch (ValidationException e) {// 验证异常 - 记录警告并返回错误logger.warn("Validation failed: {}", e.getMessage());setValidationError(context, e.getMessage());return false;} catch (BusinessException e) {// 业务异常 - 记录错误并返回业务错误logger.error("Business error: {}", e.getMessage());setBusinessError(context, e);return false;} catch (SystemException e) {// 系统异常 - 记录错误并重新抛出logger.error("System error", e);throw e;} catch (Exception e) {// 未知异常 - 包装后重新抛出logger.error("Unexpected error", e);throw new ChainExecutionException("Unexpected error in handler", e);}}
}

3. 性能监控

public class PerformanceMonitoringExample {@Overrideprotected boolean doHandle(Context context) {long startTime = System.currentTimeMillis();try {boolean result = processRequest(context);// 记录成功处理的性能指标long duration = System.currentTimeMillis() - startTime;recordPerformanceMetrics(context, duration, true);return result;} catch (Exception e) {// 记录失败处理的性能指标long duration = System.currentTimeMillis() - startTime;recordPerformanceMetrics(context, duration, false);throw e;}}private void recordPerformanceMetrics(Context context, long duration, boolean success) {String handlerName = this.getClass().getSimpleName();// 记录到监控系统MetricsCollector.recordHandlerDuration(handlerName, duration);MetricsCollector.recordHandlerResult(handlerName, success);// 记录到上下文context.setAttribute(handlerName + "_duration", duration);context.setAttribute(handlerName + "_success", success);}
}

终止条件判断

1. 基于返回值的终止

public class ReturnBasedTermination {@Overrideprotected boolean doHandle(Context context) {// 处理成功，继续链if (processSuccessfully(context)) {return true;}// 处理失败，终止链return false;}
}

2. 基于上下文状态的终止

public class ContextBasedTermination {@Overrideprotected boolean doHandle(Context context) {processRequest(context);// 检查上下文中的终止标志Boolean shouldTerminate = context.getAttribute("terminate_chain", Boolean.class);return !Boolean.TRUE.equals(shouldTerminate);}
}

3. 基于异常的终止

public class ExceptionBasedTermination {@Overrideprotected boolean doHandle(Context context) {try {processRequest(context);return true;} catch (TerminateChainException e) {// 特定异常表示需要终止链logger.info("Chain terminated by handler: {}", e.getMessage());return false;}}
}

最佳实践

1. 单一职责

// 好的实践：职责单一
public class AuthenticationHandler extends AbstractHandler {// 只负责认证逻辑
}public class AuthorizationHandler extends AbstractHandler {// 只负责授权逻辑
}// 不好的实践：职责混合
public class AuthHandler extends AbstractHandler {// 既负责认证又负责授权，职责不清
}

2. 状态无关

// 好的实践：无状态处理器
public class StatelessHandler extends AbstractHandler {// 不保存实例状态，线程安全@Overrideprotected boolean doHandle(Context context) {// 所有数据都从context获取return true;}
}// 不好的实践：有状态处理器
public class StatefulHandler extends AbstractHandler {private String lastProcessedId; // 实例状态，线程不安全@Overrideprotected boolean doHandle(Context context) {lastProcessedId = context.getRequest().getId();return true;}
}

3. 错误处理

public class ProperErrorHandling extends AbstractHandler {@Overrideprotected boolean doHandle(Context context) {try {return processRequest(context);} catch (RecoverableException e) {// 可恢复异常，记录日志并继续logger.warn("Recoverable error: {}", e.getMessage());return true;} catch (FatalException e) {// 致命异常，记录日志并终止logger.error("Fatal error: {}", e.getMessage());setErrorResponse(context, e);return false;}}
}

总结

处理器实现是责任链框架的核心，需要遵循以下原则：

  1. 单一职责：每个处理器只负责一个特定的功能
  2. 状态无关：处理器应该是无状态的，确保线程安全
  3. 明确终止：清晰地定义何时继续传递，何时终止链
  4. 异常处理：合理处理各种异常情况
  5. 性能监控：记录处理时间和结果，便于性能分析
  6. 日志记录：提供详细的日志信息，便于问题排查

在下一章中，我们将介绍如何使用构建器模式来优雅地构建责任链。

http://www.xdnf.cn/news/20350.html

相关文章：

  • 《Science》神经炎症综述思路套用：从机制到跨领域研究范式
  • Python实现生成矩形框、三角形框、六边形框和圆环点云
  • 自动拆箱和装箱的原理与作用
  • HMI（人机界面）
  • 【基础-单选】UIAbility实例创建完成时触发的回调
  • HTML 列表类型
  • 5-8单元格区域与VS数组应用(实例:提取满足条件的数据)
  • Qt多线程编程学习
  • EG2103 SOP-8 内置600V功率MOS管 栅极驱动芯片
  • I/O 多路复用 (I/O Multiplexing)
  • 四个关于云属性的四个卫星数据集的介绍
  • 基于Spring Boot + Vue3的办公用品申领管理系统
  • 部署AIRI
  • lesson55：CSS导航组件全攻略：从基础导航条到动态三级菜单与伸缩菜单实现
  • 02.继承MonoBehaviour的单例模式基类
  • Python快速入门专业版（七）：整数与浮点数：Python数值类型的运算与精度问题（附解决方案）
  • 项目中的一些比较实用的自定义控件
  • Python文件打包为EXE的工具v1.0
  • 《AI大模型应知应会100篇》第67篇 Web应用与大模型集成开发实践——1小时打造国产大模型智能客服系统
  • MySQL问题5
  • github上传步骤
  • 季度最强策略：年化247%，回撤10%，夏普比率3.79。附大小盘轮动策略python源代码。
  • Nestjs框架: 使用 CASL 库实现基于角色的权限控制（RBAC）与细粒度访问控制的实战演示
  • 【嵌入式C语言】七
  • 【IQA技术专题】 多尺度的transformer网络IQA：MUSIQ
  • GO语言的主要语法和特性
  • 跨平台游戏引擎 Axmol-2.8.1 发布
  • 突破反爬限制：动态IP轮换策略与实现
  • XXL-JOB源码分析（服务端）
  • “唐人街大赛第二届”题解