详解SpringCloud Finchley Gateway 统一异常处理

SpringCloud Finchley Gateway 统一异常处理

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1 . 问题：使用SpringCloud Gateway时，会出现各种系统级异常，默认返回HTML.

2 . Finchley版本的Gateway，使用WebFlux形式作为底层框架，而不是Servlet容器，所以常规的异常处理无法使用

翻阅源码，默认是使用DefaultErrorWebExceptionHandler这个类实现结构如下：

可以实现参考DefaultErrorWebExceptionHandler和AbstractErrorWebExceptionHandler自定义实现ErrorWebExceptionHandler，然后，注册为Bean到Spring容器中即可（Bean Name:"errorWebExceptionHandler"）

具体实现代码如下：

package pro.chenggang.example.spring.cloud.gateway.support;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.web.reactive.error.ErrorWebExceptionHandler;
import org.springframework.cloud.gateway.support.NotFoundException;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.codec.HttpMessageReader;
import org.springframework.http.codec.HttpMessageWriter;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.util.Assert;
import org.springframework.web.reactive.function.BodyInserters;
import org.springframework.web.reactive.function.server.RequestPredicates;
import org.springframework.web.reactive.function.server.RouterFunctions;
import org.springframework.web.reactive.function.server.ServerRequest;
import org.springframework.web.reactive.function.server.ServerResponse;
import org.springframework.web.reactive.result.view.ViewResolver;
import org.springframework.web.server.ResponseStatusException;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;

import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;


public class JsonExceptionHandler implements ErrorWebExceptionHandler {

 private static final Logger log = LoggerFactory.getLogger(JsonExceptionHandler.class);

 
 private List> messageReaders = Collections.emptyList();

 
 private List> messageWriters = Collections.emptyList();

 
 private List viewResolvers = Collections.emptyList();

 
 private ThreadLocal> exceptionHandlerResult = new ThreadLocal<>();

 
 public void setMessageReaders(List> messageReaders) {
  Assert.notNull(messageReaders, "'messageReaders' must not be null");
  this.messageReaders = messageReaders;
 }

 
 public void setViewResolvers(List viewResolvers) {
  this.viewResolvers = viewResolvers;
 }

 
 public void setMessageWriters(List> messageWriters) {
  Assert.notNull(messageWriters, "'messageWriters' must not be null");
  this.messageWriters = messageWriters;
 }

 @Override
 public Mono handle(ServerWebExchange exchange, Throwable ex) {
  
  HttpStatus httpStatus;
  String body;
  if (ex instanceof NotFoundException) {
   httpStatus = HttpStatus.NOT_FOUND;
   body = "Service Not Found";
  }else if(ex instanceof ResponseStatusException) {
   ResponseStatusException responseStatusException = (ResponseStatusException) ex;
   httpStatus = responseStatusException.getStatus();
   body = responseStatusException.getMessage();
  }else{
   httpStatus = HttpStatus.INTERNAL_SERVER_ERROR;
   body ="Internal Server Error";
  }
  
  Map result = new HashMap<>(2,1);
  result.put("httpStatus",httpStatus);
  result.put("body",body);
  
  ServerHttpRequest request = exchange.getRequest();
  log.error("[全局异常处理]异常请求路径:{},记录异常信息:{}",request.getPath(),ex.getMessage());
  
  if (exchange.getResponse().isCommitted()) {
   return Mono.error(ex);
  }
  exceptionHandlerResult.set(result);
  ServerRequest newRequest = ServerRequest.create(exchange, this.messageReaders);
  return RouterFunctions.route(RequestPredicates.all(), this::renderErrorResponse).route(newRequest)
    .switchIfEmpty(Mono.error(ex))
    .flatMap((handler) -> handler.handle(newRequest))
    .flatMap((response) -> write(exchange, response));

 }

 
 protected Mono renderErrorResponse(ServerRequest request) {
  Map result = exceptionHandlerResult.get();
  return ServerResponse.status((HttpStatus) result.get("httpStatus"))
    .contentType(MediaType.APPLICATION_JSON_UTF8)
    .body(BodyInserters.fromObject(result.get("body")));
 }

 
 private Mono write(ServerWebExchange exchange,
   ServerResponse response) {
  exchange.getResponse().getHeaders()
    .setContentType(response.headers().getContentType());
  return response.writeTo(exchange, new ResponseContext());
 }

 
 private class ResponseContext implements ServerResponse.Context {

  @Override
  public List> messageWriters() {
   return JsonExceptionHandler.this.messageWriters;
  }

  @Override
  public List viewResolvers() {
   return JsonExceptionHandler.this.viewResolvers;
  }

 }
}

注册Bean

 
 @Primary
 @Bean
 @Order(Ordered.HIGHEST_PRECEDENCE)
 public ErrorWebExceptionHandler errorWebExceptionHandler(ObjectProvider> viewResolversProvider,
  ServerCodecConfigurer serverCodecConfigurer) {

  JsonExceptionHandler jsonExceptionHandler = new JsonExceptionHandler();
  jsonExceptionHandler.setViewResolvers(viewResolversProvider.getIfAvailable(Collections::emptyList));
  jsonExceptionHandler.setMessageWriters(serverCodecConfigurer.getWriters());
  jsonExceptionHandler.setMessageReaders(serverCodecConfigurer.getReaders());
  log.debug("Init Json Exception Handler Instead Default ErrorWebExceptionHandler Success");
  return jsonExceptionHandler;
 }

[@@]注意事项：

1 .上面为示例代码，其中牵扯到策略工厂和响应封装的类，可以自定义实现

2 .注册Bean时依赖的Bean，都会从Spring容器中获取到

3 .参考此方法思路，可实现统一异常处理，统一封装错误信息。

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持考高分网。