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;/** * @classDesc: 统一异常处理,参考{@link org.springframework.web.server.AbstractErrorWebExceptionHandler}修改 * @author: chenggang * @createTime: 2018/10/30 */public class JsonExceptionHandler implements ErrorWebExceptionHandler { private static final Logger log = LoggerFactory.getLogger(JsonExceptionHandler.class); /** * MessageReader */ private List<HttpMessageReader<?>> messageReaders = Collections.emptyList(); /** * MessageWriter */ private List<HttpMessageWriter<?>> messageWriters = Collections.emptyList(); /** * ViewResolvers */ private List<ViewResolver> viewResolvers = Collections.emptyList(); /** * 存储处理异常后的信息 */ private ThreadLocal<Map<String,Object>> exceptionHandlerResult = new ThreadLocal<>(); /** * 参考AbstractErrorWebExceptionHandler * @param messageReaders */ public void setMessageReaders(List<HttpMessageReader<?>> messageReaders) { Assert.notNull(messageReaders, "'messageReaders' must not be null"); this.messageReaders = messageReaders; } /** * 参考AbstractErrorWebExceptionHandler * @param viewResolvers */ public void setViewResolvers(List<ViewResolver> viewResolvers) { this.viewResolvers = viewResolvers; } /** * 参考AbstractErrorWebExceptionHandler * @param messageWriters */ public void setMessageWriters(List<HttpMessageWriter<?>> messageWriters) { Assert.notNull(messageWriters, "'messageWriters' must not be null"); this.messageWriters = messageWriters; } @Override public Mono<Void> handle(ServerWebExchange exchange, Throwable ex) { /** * 按照异常类型进行处理 */ 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"; } /** * 封装响应体,此body可修改为自己的jsonBody */ Map<String,Object> result = new HashMap<>(2,1); result.put("httpStatus",httpStatus); result.put("body",body); /** * 错误记录 */ 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()); /** * 参考AbstractErrorWebExceptionHandler */ 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)); } /** * 参考DefaultErrorWebExceptionHandler * @param request * @return */ protected Mono<ServerResponse> renderErrorResponse(ServerRequest request) { Map<String,Object> result = exceptionHandlerResult.get(); return ServerResponse.status((HttpStatus) result.get("httpStatus")) .contentType(MediaType.APPLICATION_JSON_UTF8) .body(BodyInserters.fromObject(result.get("body"))); } /** * 参考AbstractErrorWebExceptionHandler * @param exchange * @param response * @return */ private Mono<? extends Void> write(ServerWebExchange exchange, ServerResponse response) { exchange.getResponse().getHeaders() .setContentType(response.headers().getContentType()); return response.writeTo(exchange, new ResponseContext()); } /** * 参考AbstractErrorWebExceptionHandler */ private class ResponseContext implements ServerResponse.Context { @Override public List<HttpMessageWriter<?>> messageWriters() { return JsonExceptionHandler.this.messageWriters; } @Override public List<ViewResolver> viewResolvers() { return JsonExceptionHandler.this.viewResolvers; } }}

注册Bean

/** * 自定义异常处理[@@]注册Bean时依赖的Bean，会从容器中直接获取，所以直接注入即可 * @param viewResolversProvider * @param serverCodecConfigurer * @return */ @Primary @Bean @Order(Ordered.HIGHEST_PRECEDENCE) public ErrorWebExceptionHandler errorWebExceptionHandler(ObjectProvider<List<ViewResolver>> 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。