Spring Cloud Gateway全局异常处理的方法详解

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;
 }

}

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;
 } 
}

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

protected RouterFunction<ServerResponse> getRoutingFunction(ErrorAttributes errorAttributes) {
 return RouterFunctions.route(RequestPredicates.all(), this::renderErrorResponse);
}

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

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