Spring Cloud學習教程之Zuul統一異常處理與回退

前言

Zuul 是Netflix 提供的一個開源組件,致力於在雲平台上提供動態路由，監控，彈性，安全等邊緣服務的框架。也有很多公司使用它來作為網關的重要組成部分，碰巧今年公司的架構組決定自研一個網關產品，集動態路由，動態權限，限流配額等功能為一體，為其他部門的項目提供統一的外網調用管理，最終形成產品(這方面阿里其實已經有成熟的網關產品了，但是不太適用於個性化的配置，也沒有集成權限和限流降級)。

本文主要給大家介紹了關於Spring Cloud Zuul統一異常處理與回退的相關內容，分享出來供大家參考學習，下面話不多說了，來一起看看詳細的介紹吧。

一、Filter中統一異常處理

其實在SpringCloud的Edgware SR2版本中對於ZuulFilter中的錯誤有統一的處理，但是在實際開發當中對於錯誤的響應方式，我想每個團隊都有自己的處理規範。那麼如何做到自定義的異常處理呢？

我們可以先參考一下SpringCloud提供的SendErrorFilter:

 /* * Copyright 2013-2015 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */package org.springframework.cloud.netflix.zuul.filters.post;import javax.servlet.RequestDispatcher;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.apache.commons.logging.Log;import org.apache.commons.logging.LogFactory;import org.springframework.beans.factory.annotation.Value;import org.springframework.cloud.netflix.zuul.util.ZuulRuntimeException;import org.springframework.util.ReflectionUtils;import org.springframework.util.StringUtils;import com.netflix.zuul.ZuulFilter;import com.netflix.zuul.context.RequestContext;import com.netflix.zuul.exception.ZuulException;import static org.springframework.cloud.netflix.zuul.filters.support.FilterConstants.ERROR_TYPE;import static org.springframework.cloud.netflix.zuul.filters.support.FilterConstants.SEND_ERROR_FILTER_ORDER;/** * Error {@link ZuulFilter} that forwards to /error (by default) if {@link RequestContext#getThrowable()} is not null. * * @author Spencer Gibb *///TODO: move to error package in Edgwarepublic class SendErrorFilter extends ZuulFilter { private static final Log log = LogFactory.getLog(SendErrorFilter.class); protected static final String SEND_ERROR_FILTER_RAN = "sendErrorFilter.ran"; @Value("${error.path:/error}") private String errorPath; @Override public String filterType() { return ERROR_TYPE; } @Override public int filterOrder() { return SEND_ERROR_FILTER_ORDER; } @Override public boolean shouldFilter() { RequestContext ctx = RequestContext.getCurrentContext(); // only forward to errorPath if it hasn't been forwarded to already return ctx.getThrowable() != null && !ctx.getBoolean(SEND_ERROR_FILTER_RAN, false); } @Override public Object run() { try { RequestContext ctx = RequestContext.getCurrentContext(); ZuulException exception = findZuulException(ctx.getThrowable()); HttpServletRequest request = ctx.getRequest(); request.setAttribute("javax.servlet.error.status_code", exception.nStatusCode); log.warn("Error during filtering", exception); request.setAttribute("javax.servlet.error.exception", exception); if (StringUtils.hasText(exception.errorCause)) { request.setAttribute("javax.servlet.error.message", exception.errorCause); } RequestDispatcher dispatcher = request.getRequestDispatcher( this.errorPath); if (dispatcher != null) { ctx.set(SEND_ERROR_FILTER_RAN, true); if (!ctx.getResponse().isCommitted()) { ctx.setResponseStatusCode(exception.nStatusCode); dispatcher.forward(request, ctx.getResponse()); } } } catch (Exception ex) { ReflectionUtils.rethrowRuntimeException(ex); } return null; } ZuulException findZuulException(Throwable throwable) { if (throwable.getCause() instanceof ZuulRuntimeException) { // this was a failure initiated by one of the local filters return (ZuulException) throwable.getCause().getCause(); } if (throwable.getCause() instanceof ZuulException) { // wrapped zuul exception return (ZuulException) throwable.getCause(); } if (throwable instanceof ZuulException) { // exception thrown by zuul lifecycle return (ZuulException) throwable; } // fallback, should never get here return new ZuulException(throwable, HttpServletResponse.SC_INTERNAL_SERVER_ERROR, null); } public void setErrorPath(String errorPath) { this.errorPath = errorPath; }}

在這裡我們可以找到幾個關鍵點：

1）在上述代碼中，我們可以發現filter已經將相關的錯誤信息放到request當中了：

request.setAttribute("javax.servlet.error.status_code", exception.nStatusCode);

request.setAttribute("javax.servlet.error.exception", exception);

request.setAttribute("javax.servlet.error.message", exception.errorCause);

2）錯誤處理完畢後，會轉發到xxx/error的地址來處理

那麼我們可以來做個試驗,我們在gateway-service項目模塊裡，創建一個會拋出異常的filter:

 package com.hzgj.lyrk.springcloud.gateway.server.filter;import com.netflix.zuul.ZuulFilter;import lombok.extern.slf4j.Slf4j;import org.springframework.stereotype.Component;@Component@Slf4jpublic class MyZuulFilter extends ZuulFilter { @Override public String filterType() { return "post"; } @Override public int filterOrder() { return 9; } @Override public boolean shouldFilter() { return true; } @Override public Object run() { log.info("run error test ..."); throw new RuntimeException(); // return null; }}

緊接著我們定義一個控制器，來做錯誤處理：

 package com.hzgj.lyrk.springcloud.gateway.server.filter;import org.springframework.http.HttpStatus;import org.springframework.http.ResponseEntity;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.RestController;import javax.servlet.http.HttpServletRequest;@RestControllerpublic class ErrorHandler { @GetMapping(value = "/error") public ResponseEntity<ErrorBean> error(HttpServletRequest request) { String message = request.getAttribute("javax.servlet.error.message").toString(); ErrorBean errorBean = new ErrorBean(); errorBean.setMessage(message); errorBean.setReason("程序出錯"); return new ResponseEntity<>(errorBean, HttpStatus.BAD_GATEWAY); } private static class ErrorBean { private String message; private String reason; public String getMessage() { return message; } public void setMessage(String message) { this.message = message; } public String getReason() { return reason; } public void setReason(String reason) { this.reason = reason; } }}

啟動項目後，我們通過網關訪問一下試試：

二、關於zuul回退的問題

1、關於zuul的超時問題：

這個問題網上有很多解決方案,但是我還要貼一下源代碼，請關注這個類AbstractRibbonCommand，在這個類裡集成了hystrix與ribbon。

 /* * Copyright 2013-2016 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * */package org.springframework.cloud.netflix.zuul.filters.route.support;import org.apache.commons.logging.Log;import org.apache.commons.logging.LogFactory;import org.springframework.cloud.netflix.ribbon.RibbonClientConfiguration;import org.springframework.cloud.netflix.ribbon.RibbonHttpResponse;import org.springframework.cloud.netflix.ribbon.support.AbstractLoadBalancingClient;import org.springframework.cloud.netflix.ribbon.support.ContextAwareRequest;import org.springframework.cloud.netflix.zuul.filters.ZuulProperties;import org.springframework.cloud.netflix.zuul.filters.route.RibbonCommand;import org.springframework.cloud.netflix.zuul.filters.route.RibbonCommandContext;import org.springframework.cloud.netflix.zuul.filters.route.ZuulFallbackProvider;import org.springframework.cloud.netflix.zuul.filters.route.FallbackProvider;import org.springframework.http.client.ClientHttpResponse;import com.netflix.client.AbstractLoadBalancerAwareClient;import com.netflix.client.ClientRequest;import com.netflix.client.config.DefaultClientConfigImpl;import com.netflix.client.config.IClientConfig;import com.netflix.client.config.IClientConfigKey;import com.netflix.client.http.HttpResponse;import com.netflix.config.DynamicIntProperty;import com.netflix.config.DynamicPropertyFactory;import com.netflix.hystrix.HystrixCommand;import com.netflix.hystrix.HystrixCommandGroupKey;import com.netflix.hystrix.HystrixCommandKey;import com.netflix.hystrix.HystrixCommandProperties;import com.netflix.hystrix.HystrixCommandProperties.ExecutionIsolationStrategy;import com.netflix.hystrix.HystrixThreadPoolKey;import com.netflix.zuul.constants.ZuulConstants;import com.netflix.zuul.context.RequestContext;/** * @author Spencer Gibb */public abstract class AbstractRibbonCommand<LBC extends AbstractLoadBalancerAwareClient<RQ, RS>, RQ extends ClientRequest, RS extends HttpResponse> extends HystrixCommand<ClientHttpResponse> implements RibbonCommand { private static final Log LOGGER = LogFactory.getLog(AbstractRibbonCommand.class); protected final LBC client; protected RibbonCommandContext context; protected ZuulFallbackProvider zuulFallbackProvider; protected IClientConfig config; public AbstractRibbonCommand(LBC client, RibbonCommandContext context, ZuulProperties zuulProperties) { this("default", client, context, zuulProperties); } public AbstractRibbonCommand(String commandKey, LBC client, RibbonCommandContext context, ZuulProperties zuulProperties) { this(commandKey, client, context, zuulProperties, null); } public AbstractRibbonCommand(String commandKey, LBC client, RibbonCommandContext context, ZuulProperties zuulProperties, ZuulFallbackProvider fallbackProvider) { this(commandKey, client, context, zuulProperties, fallbackProvider, null); } public AbstractRibbonCommand(String commandKey, LBC client, RibbonCommandContext context, ZuulProperties zuulProperties, ZuulFallbackProvider fallbackProvider, IClientConfig config) { this(getSetter(commandKey, zuulProperties, config), client, context, fallbackProvider, config); } protected AbstractRibbonCommand(Setter setter, LBC client, RibbonCommandContext context, ZuulFallbackProvider fallbackProvider, IClientConfig config) { super(setter); this.client = client; this.context = context; this.zuulFallbackProvider = fallbackProvider; this.config = config; } protected static HystrixCommandProperties.Setter createSetter(IClientConfig config, String commandKey, ZuulProperties zuulProperties) { int hystrixTimeout = getHystrixTimeout(config, commandKey); return HystrixCommandProperties.Setter().withExecutionIsolationStrategy( zuulProperties.getRibbonIsolationStrategy()).withExecutionTimeoutInMilliseconds(hystrixTimeout); } protected static int getHystrixTimeout(IClientConfig config, String commandKey) { int ribbonTimeout = getRibbonTimeout(config, commandKey); DynamicPropertyFactory dynamicPropertyFactory = DynamicPropertyFactory.getInstance(); int defaultHystrixTimeout = dynamicPropertyFactory.getIntProperty("hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds", 0).get(); int commandHystrixTimeout = dynamicPropertyFactory.getIntProperty("hystrix.command." + commandKey + ".execution.isolation.thread.timeoutInMilliseconds", 0).get(); int hystrixTimeout; if(commandHystrixTimeout > 0) { hystrixTimeout = commandHystrixTimeout; } else if(defaultHystrixTimeout > 0) { hystrixTimeout = defaultHystrixTimeout; } else { hystrixTimeout = ribbonTimeout; } if(hystrixTimeout < ribbonTimeout) { LOGGER.warn("The Hystrix timeout of " + hystrixTimeout + "ms for the command " + commandKey + " is set lower than the combination of the Ribbon read and connect timeout, " + ribbonTimeout + "ms."); } return hystrixTimeout; } protected static int getRibbonTimeout(IClientConfig config, String commandKey) { int ribbonTimeout; if (config == null) { ribbonTimeout = RibbonClientConfiguration.DEFAULT_READ_TIMEOUT + RibbonClientConfiguration.DEFAULT_CONNECT_TIMEOUT; } else { int ribbonReadTimeout = getTimeout(config, commandKey, "ReadTimeout", IClientConfigKey.Keys.ReadTimeout, RibbonClientConfiguration.DEFAULT_READ_TIMEOUT); int ribbonConnectTimeout = getTimeout(config, commandKey, "ConnectTimeout", IClientConfigKey.Keys.ConnectTimeout, RibbonClientConfiguration.DEFAULT_CONNECT_TIMEOUT); int maxAutoRetries = getTimeout(config, commandKey, "MaxAutoRetries", IClientConfigKey.Keys.MaxAutoRetries, DefaultClientConfigImpl.DEFAULT_MAX_AUTO_RETRIES); int maxAutoRetriesNextServer = getTimeout(config, commandKey, "MaxAutoRetriesNextServer", IClientConfigKey.Keys.MaxAutoRetriesNextServer, DefaultClientConfigImpl.DEFAULT_MAX_AUTO_RETRIES_NEXT_SERVER); ribbonTimeout = (ribbonReadTimeout + ribbonConnectTimeout) * (maxAutoRetries + 1) * (maxAutoRetriesNextServer + 1); } return ribbonTimeout; } private static int getTimeout(IClientConfig config, String commandKey, String property, IClientConfigKey<Integer> configKey, int defaultValue) { DynamicPropertyFactory dynamicPropertyFactory = DynamicPropertyFactory.getInstance(); return dynamicPropertyFactory.getIntProperty(commandKey + "." + config.getNameSpace() + "." + property, config.get(configKey, defaultValue)).get(); } @Deprecated //TODO remove in 2.0.x protected static Setter getSetter(final String commandKey, ZuulProperties zuulProperties) { return getSetter(commandKey, zuulProperties, null); } protected static Setter getSetter(final String commandKey, ZuulProperties zuulProperties, IClientConfig config) { // @formatter:off Setter commandSetter = Setter.withGroupKey(HystrixCommandGroupKey.Factory.asKey("RibbonCommand")) .andCommandKey(HystrixCommandKey.Factory.asKey(commandKey)); final HystrixCommandProperties.Setter setter = createSetter(config, commandKey, zuulProperties); if (zuulProperties.getRibbonIsolationStrategy() == ExecutionIsolationStrategy.SEMAPHORE){ final String name = ZuulConstants.ZUUL_EUREKA + commandKey + ".semaphore.maxSemaphores"; // we want to default to semaphore-isolation since this wraps // 2 others commands that are already thread isolated final DynamicIntProperty value = DynamicPropertyFactory.getInstance() .getIntProperty(name, zuulProperties.getSemaphore().getMaxSemaphores()); setter.withExecutionIsolationSemaphoreMaxConcurrentRequests(value.get()); } else if (zuulProperties.getThreadPool().isUseSeparateThreadPools()) { final String threadPoolKey = zuulProperties.getThreadPool().getThreadPoolKeyPrefix() + commandKey; commandSetter.andThreadPoolKey(HystrixThreadPoolKey.Factory.asKey(threadPoolKey)); } return commandSetter.andCommandPropertiesDefaults(setter); // @formatter:on } @Override protected ClientHttpResponse run() throws Exception { final RequestContext context = RequestContext.getCurrentContext(); RQ request = createRequest(); RS response; boolean retryableClient = this.client instanceof AbstractLoadBalancingClient && ((AbstractLoadBalancingClient)this.client).isClientRetryable((ContextAwareRequest)request); if (retryableClient) { response = this.client.execute(request, config); } else { response = this.client.executeWithLoadBalancer(request, config); } context.set("ribbonResponse", response); // Explicitly close the HttpResponse if the Hystrix command timed out to // release the underlying HTTP connection held by the response. // if (this.isResponseTimedOut()) { if (response != null) { response.close(); } } return new RibbonHttpResponse(response); } @Override protected ClientHttpResponse getFallback() { if(zuulFallbackProvider != null) { return getFallbackResponse(); } return super.getFallback(); } protected ClientHttpResponse getFallbackResponse() { if (zuulFallbackProvider instanceof FallbackProvider) { Throwable cause = getFailedExecutionException(); cause = cause == null ? getExecutionException() : cause; if (cause == null) { zuulFallbackProvider.fallbackResponse(); } else { return ((FallbackProvider) zuulFallbackProvider).fallbackResponse(cause); } } return zuulFallbackProvider.fallbackResponse(); } public LBC getClient() { return client; } public RibbonCommandContext getContext() { return context; } protected abstract RQ createRequest() throws Exception;}

請注意： getRibbonTimeout方法與getHystrixTimeout方法，其中這兩個方法commandKey的值為路由的名稱，比如說我們訪問:http://localhost:8088/order-server/xxx來訪問order-server服務， 那麼commandKey 就為order-server

根據源代碼，我們先設置gateway-server的超時參數：

 #全局的ribbon設置ribbon: ConnectTimeout: 3000 ReadTimeout: 3000hystrix: command: default: execution: isolation: thread: timeoutInMilliseconds: 3000zuul: host: connectTimeoutMillis: 10000

當然也可以單獨為order-server設置ribbon的超時參數：order-server.ribbon.xxxx=xxx , 為了演示zuul中的回退效果，我在這裡把Hystrix超時時間設置短一點。當然最好不要將Hystrix默認的超時時間設置的比Ribbon的超時時間短，源碼裡遇到此情況已經給與我們警告了。

那麼我們在order-server下添加如下方法：

 @GetMapping("/sleep/{sleepTime}") public String sleep(@PathVariable Long sleepTime) throws InterruptedException { TimeUnit.SECONDS.sleep(sleepTime); return "SUCCESS"; }

2、zuul的回退方法

我們可以實現ZuulFallbackProvider接口,實現代碼：

 package com.hzgj.lyrk.springcloud.gateway.server.filter;import com.google.common.collect.ImmutableMap;import com.google.gson.GsonBuilder;import org.springframework.cloud.netflix.zuul.filters.route.ZuulFallbackProvider;import org.springframework.http.HttpHeaders;import org.springframework.http.HttpStatus;import org.springframework.http.MediaType;import org.springframework.http.client.ClientHttpResponse;import org.springframework.stereotype.Component;import java.io.ByteArrayInputStream;import java.io.IOException;import java.io.InputStream;import java.time.LocalDateTime;import java.time.LocalTime;@Componentpublic class FallBackHandler implements ZuulFallbackProvider { @Override public String getRoute() { //代表所有的路由都適配該設置return "*"; } @Override public ClientHttpResponse fallbackResponse() { return new ClientHttpResponse() { @Override public HttpStatus getStatusCode() throws IOException { return HttpStatus.OK; } @Override public int getRawStatusCode() throws IOException { return 200; } @Override public String getStatusText() throws IOException { return "OK"; } @Override public void close() { } @Override public InputStream getBody() throws IOException { String result = new GsonBuilder().create().toJson(ImmutableMap.of("errorCode", 500, "content", "請求失敗", "time", LocalDateTime.now())); return new ByteArrayInputStream(result.getBytes()); } @Override public HttpHeaders getHeaders() { HttpHeaders headers = new HttpHeaders(); headers.setContentType(MediaType.APPLICATION_JSON); return headers; } }; }}

此時我們訪問：http://localhost:8088/order-server/sleep/6 得到如下結果：

當我們訪問：http://localhost:8088/order-server/sleep/1 就得到如下結果：

總結

以上就是這篇文章的全部內容了，希望本文的內容對大家的學習或者工作具有一定的參考學習價值，如果有疑問大家可以留言交流，謝謝大家對武林網的支持。