Spring Cloud Gateway中的全局異常處理不能直接用@ControllerAdvice來處理，通過跟蹤異常信息的拋出，找到對應的源碼，自定義一些處理邏輯來符合業務的需求。

網關都是給接口做代理轉發的，后端對應的都是REST API，返回數據格式都是JSON。如果不做處理，當發生異常時，Gateway默認給出的錯誤信息是頁面，不方便前端進行異常處理。

需要對異常信息進行處理，返回JSON格式的數據給客戶端。下面先看實現的代碼，后面再跟大家講下需要注意的地方。

自定義異常處理邏輯：

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;/*** 自定義異常處理* * <p>異常時用JSON代替HTML異常信息<p>* * @author yinjihuan**/ public class JsonExceptionHandler extends DefaultErrorWebExceptionHandler { ? ?public JsonExceptionHandler(ErrorAttributes errorAttributes, ResourceProperties resourceProperties,?ErrorProperties errorProperties, ApplicationContext applicationContext) { ? ? ? ?super(errorAttributes, resourceProperties, errorProperties, applicationContext);} ? ?/*** 獲取異常屬性*/@Overrideprotected 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));} ? ?/*** 指定響應處理方法為JSON處理的方法* @param errorAttributes*/@Overrideprotected RouterFunction<ServerResponse> getRoutingFunction(ErrorAttributes errorAttributes) { ? ? ? ?return RouterFunctions.route(RequestPredicates.all(), this::renderErrorResponse);} ? ?/*** 根據code獲取對應的HttpStatus* @param errorAttributes*/@Overrideprotected HttpStatus getHttpStatus(Map<String, Object> errorAttributes) { ? ? ? ?int statusCode = (int) errorAttributes.get("code"); ? ? ? ?return HttpStatus.valueOf(statusCode);} ? ?/*** 構建異常信息* @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();} ? ?/*** 構建返回的JSON數據格式* @param status ? ? ? ?狀態碼* @param errorMessage ?異常信息* @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;}}

覆蓋默認的配置：

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;/*** 覆蓋默認的異常處理* * @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;}}

注意點

• 異常時如何返回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，原代碼如下：

@Override protected RouterFunction<ServerResponse> getRoutingFunction(ErrorAttributes errorAttributes) { ? ? ? return RouterFunctions.route(acceptsTextHtml(), this::renderErrorView).andRoute(RequestPredicates.all(), this::renderErrorResponse); }

這邊優先是用HTML來顯示的，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需要重寫

原始的方法是通過status來獲取對應的HttpStatus的，代碼如下：

protected HttpStatus getHttpStatus(Map<String, Object> errorAttributes) { ? ? ?int statusCode = (int) errorAttributes.get("status"); ? ? ?return HttpStatus.valueOf(statusCode); }

如果我們定義的格式中沒有status字段的話，這么就會報錯，找不到對應的響應碼，要么返回數據格式中增加status子段，要么重寫，我這邊返回的是code，所以要重寫，代碼如下：

@Override protected HttpStatus getHttpStatus(Map<String, Object> errorAttributes) { ? ?int statusCode = (int) errorAttributes.get("code"); ? ?return HttpStatus.valueOf(statusCode); } 《新程序員》：云原生和全面數字化實踐50位技術專家共同創作，文字、視頻、音頻交互閱讀

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