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：
@Overrideprotected 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：
@Overrideprotected HttpStatus getHttpStatus(Map<String, Object> errorAttributes) { int statusCode = (int) errorAttributes.get("code"); return HttpStatus.valueOf(statusCode);
}
