Spring Cloud Gateway全局异常处理的方法详解
前言
Spring Cloud Gateway是Spring官方基于Spring 5.0,Spring Boot 2.0和Project Reactor等技术开发的网关,Spring Cloud Gateway旨在为微服务架构提供一种简单而有效的统一的API路由管理方式。Spring Cloud Gateway作为Spring Cloud生态系中的网关,目标是替代Netflix ZUUL,其不仅提供统一的路由方式,并且基于Filter链的方式提供了网关基本的功能,例如:安全,监控/埋点,和限流等。
Spring Cloud Gateway 的特征:
- 基于 Spring Framework 5,Project Reactor 和 Spring Boot 2.0动态路由
- Predicates 和 Filters 作用于特定路由
- 集成 Hystrix 断路器
- 集成 Spring Cloud DiscoveryClient
- 易于编写的 Predicates 和 Filters
- 限流
- 路径重写
Spring Cloud Gateway中的全局异常处理不能直接用@ControllerAdvice来处理,通过跟踪异常信息的抛出,找到对应的源码,自定义一些处理逻辑来符合业务的需求。
网关都是给接口做代理转发的,后端对应的都是REST API,返回数据格式都是JSON。如果不做处理,当发生异常时,Gateway默认给出的错误信息是页面,不方便前端进行异常处理。
需要对异常信息进行处理,返回JSON格式的数据给客户端。下面先看实现的代码,后面再跟大家讲下需要注意的地方。
自定义异常处理逻辑:
package com.cxytiandi.gateway.exception; import java.util.HashMap; import java.util.Map; import org.springframework.boot.autoconfigure.web.ErrorProperties; import org.springframework.boot.autoconfigure.web.ResourceProperties; import org.springframework.boot.autoconfigure.web.reactive.error.DefaultErrorWebExceptionHandler; import org.springframework.boot.web.reactive.error.ErrorAttributes; import org.springframework.context.ApplicationContext; import org.springframework.http.HttpStatus; import org.springframework.web.reactive.function.server.RequestPredicates; import org.springframework.web.reactive.function.server.RouterFunction; import org.springframework.web.reactive.function.server.RouterFunctions; import org.springframework.web.reactive.function.server.ServerRequest; import org.springframework.web.reactive.function.server.ServerResponse; /** * 自定义异常处理 * * <p>异常时用JSON代替HTML异常信息<p> * * @author yinjihuan * */ public class JsonExceptionHandler extends DefaultErrorWebExceptionHandler { public JsonExceptionHandler(ErrorAttributes errorAttributes, ResourceProperties resourceProperties, ErrorProperties errorProperties, ApplicationContext applicationContext) { super(errorAttributes, resourceProperties, errorProperties, applicationContext); } /** * 获取异常属性 */ @Override protected Map<String, Object> getErrorAttributes(ServerRequest request, boolean includeStackTrace) { int code = 500; Throwable error = super.getError(request); if (error instanceof org.springframework.cloud.gateway.support.NotFoundException) { code = 404; } return response(code, this.buildMessage(request, error)); } /** * 指定响应处理方法为JSON处理的方法 * @param errorAttributes */ @Override protected RouterFunction<ServerResponse> getRoutingFunction(ErrorAttributes errorAttributes) { return RouterFunctions.route(RequestPredicates.all(), this::renderErrorResponse); } /** * 根据code获取对应的HttpStatus * @param errorAttributes */ @Override protected HttpStatus getHttpStatus(Map<String, Object> errorAttributes) { int statusCode = (int) errorAttributes.get("code"); return HttpStatus.valueOf(statusCode); } /** * 构建异常信息 * @param request * @param ex * @return */ private String buildMessage(ServerRequest request, Throwable ex) { StringBuilder message = new StringBuilder("Failed to handle request ["); message.append(request.methodName()); message.append(" "); message.append(request.uri()); message.append("]"); if (ex != null) { message.append(": "); message.append(ex.getMessage()); } return message.toString(); } /** * 构建返回的JSON数据格式 * @param status 状态码 * @param errorMessage 异常信息 * @return */ public static Map<String, Object> response(int status, String errorMessage) { Map<String, Object> map = new HashMap<>(); map.put("code", status); map.put("message", errorMessage); map.put("data", null); return map; } }
覆盖默认的配置:
package com.cxytiandi.gateway.exception; import java.util.Collections; import java.util.List; import org.springframework.beans.factory.ObjectProvider; import org.springframework.boot.autoconfigure.web.ResourceProperties; import org.springframework.boot.autoconfigure.web.ServerProperties; import org.springframework.boot.context.properties.EnableConfigurationProperties; import org.springframework.boot.web.reactive.error.ErrorAttributes; import org.springframework.boot.web.reactive.error.ErrorWebExceptionHandler; import org.springframework.context.ApplicationContext; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.core.Ordered; import org.springframework.core.annotation.Order; import org.springframework.http.codec.ServerCodecConfigurer; import org.springframework.web.reactive.result.view.ViewResolver; /** * 覆盖默认的异常处理 * * @author yinjihuan * */ @Configuration @EnableConfigurationProperties({ServerProperties.class, ResourceProperties.class}) public class ErrorHandlerConfiguration { private final ServerProperties serverProperties; private final ApplicationContext applicationContext; private final ResourceProperties resourceProperties; private final List<ViewResolver> viewResolvers; private final ServerCodecConfigurer serverCodecConfigurer; public ErrorHandlerConfiguration(ServerProperties serverProperties, ResourceProperties resourceProperties, ObjectProvider<List<ViewResolver>> viewResolversProvider, ServerCodecConfigurer serverCodecConfigurer, ApplicationContext applicationContext) { this.serverProperties = serverProperties; this.applicationContext = applicationContext; this.resourceProperties = resourceProperties; this.viewResolvers = viewResolversProvider.getIfAvailable(Collections::emptyList); this.serverCodecConfigurer = serverCodecConfigurer; } @Bean @Order(Ordered.HIGHEST_PRECEDENCE) public ErrorWebExceptionHandler errorWebExceptionHandler(ErrorAttributes errorAttributes) { JsonExceptionHandler exceptionHandler = new JsonExceptionHandler( errorAttributes, this.resourceProperties, this.serverProperties.getError(), this.applicationContext); exceptionHandler.setViewResolvers(this.viewResolvers); exceptionHandler.setMessageWriters(this.serverCodecConfigurer.getWriters()); exceptionHandler.setMessageReaders(this.serverCodecConfigurer.getReaders()); return exceptionHandler; } }
注意点
异常时如何返回JSON而不是HTML?
在org.springframework.boot.autoconfigure.web.reactive.error.DefaultErrorWebExceptionHandler中的getRoutingFunction()方法就是控制返回格式的,原代码如下:
@Override protected RouterFunction<ServerResponse> getRoutingFunction( ErrorAttributes errorAttributes) { return RouterFunctions.route(acceptsTextHtml(), this::renderErrorView) .andRoute(RequestPredicates.all(), this::renderErrorResponse); }
这边优先是用HTML来显示的,想用JSON的改下就可以了,如下:
protected RouterFunction<ServerResponse> getRoutingFunction(ErrorAttributes errorAttributes) { return RouterFunctions.route(RequestPredicates.all(), this::renderErrorResponse); }
getHttpStatus需要重写
原始的方法是通过status来获取对应的HttpStatus的,代码如下:
protected HttpStatus getHttpStatus(Map<String, Object> errorAttributes) { int statusCode = (int) errorAttributes.get("status"); return HttpStatus.valueOf(statusCode); }
如果我们定义的格式中没有status字段的话,这么就会报错,找不到对应的响应码,要么返回数据格式中增加status子段,要么重写,我这边返回的是code,所以要重写,代码如下:
@Override protected HttpStatus getHttpStatus(Map<String, Object> errorAttributes) { int statusCode = (int) errorAttributes.get("code"); return HttpStatus.valueOf(statusCode); }
总结
以上就是这篇文章的全部内容了,希望本文的内容对大家的学习或者工作具有一定的参考学习价值,如果有疑问大家可以留言交流,谢谢大家对我们的支持。