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);
- }
来源: https://juejin.im/post/5bbad1405188255c4a7137e1