hystrix应用介绍（二）
上篇博客中讲了hystrix在公司中的一些应用场景，由于保密的原因没办法贴出优化的代码，这里专门写一篇hystrix代码的demo，供大家在使用的过程中快速上手
Hystrix有两个请求命令 HystrixCommand（该方式代码的执行由新创建的线程执行）、HystrixObservableCommand（该方式代码的执行还是在主线程中执行）。
HystrixCommand用在依赖服务返回单个操作结果的时候。有两种执行方式
-execute():同步执行。从依赖的服务返回一个单一的结果对象，或是在发生错误的时候抛出异常。
-queue();异步执行。直接返回一个Future对象，其中包含了服务执行结束时要返回的单一结果对象。
HystrixObservableCommand 用在依赖服务返回多个操作结果的时候。它也实现了两种执行方式
-observe():返回Obervable对象，他代表了操作的多个结果，他是一个HotObservable
-toObservable():同样返回Observable对象，也代表了操作多个结果，但它返回的是一个Cold Observable
下边以注解和非注解两种形式演示
第一步引入所依赖的pom
<dependency>
<groupId>com.netflix.hystrix</groupId>
<artifactId>hystrix-core</artifactId>
<version>${hystrix-version}</version>
</dependency>
<dependency>
<groupId>com.netflix.hystrix</groupId>
<artifactId>hystrix-metrics-event-stream</artifactId>
<version>${hystrix-version}</version>
</dependency>
<dependency>
<groupId>com.netflix.hystrix</groupId>
<artifactId>hystrix-javanica</artifactId>
<version>${hystrix-version}</version>
</dependency>
<dependency>
<groupId>com.netflix.hystrix</groupId>
<artifactId>hystrix-servo-metrics-publisher</artifactId>
<version>${hystrix-version}</version>
</dependency>
第二步：在spring的xml配置中引入相关注解
<!-- 配置成注解方式寻找要被代理的对象 -->
<aop:aspectj-autoproxy/>
<!-- hystrix -->
<bean id="hystrixAspect" class="com.netflix.hystrix.contrib.javanica.aop.aspectj.HystrixCommandAspect"></bean>
<context:annotation-config/>
HystrixCommand代码演示
一、下边先演示 HystrixCommand的注解方式
import javafx.application.Application; import org.hope.hystrix.example.HystrixApplication; import org.hope.hystrix.example.model.User; import org.junit.Test; import org.junit.runner.RunWith; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.test.context.SpringBootTest; import org.springframework.test.context.junit4.SpringJUnit4ClassRunner; import org.springframework.test.context.web.WebAppConfiguration; import java.util.concurrent.ExecutionException; import java.util.concurrent.Future; /** * */ @RunWith(SpringJUnit4ClassRunner.class) @SpringBootTest(classes = HystrixApplication.class) public class UserServiceTest { @Autowired private UserService userService; /** * 测试同步 */ @Test public void testGetUserId() { System.out.println(Thread.currentThread().getName()); System.out.println("=================" + userService.getUserId("hystrix")); } /** * 测试异步 */ @Test public void testGetUserName() throws ExecutionException, InterruptedException { Future<String> fuature = userService.getUserName(30L,"hellow"); System.out.println("=================" + fuature.get()); } }
import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand; import com.netflix.hystrix.contrib.javanica.annotation.ObservableExecutionMode; import com.netflix.hystrix.contrib.javanica.command.AsyncResult; import org.springframework.stereotype.Service; import rx.Observable; import rx.Subscriber; import java.util.concurrent.Future; /** * 用@HystrixCommand的方式来实现 */ @Service public class UserService { /** * 同步的方式。 * fallbackMethod定义降级 */ @HystrixCommand(fallbackMethod = "helloFallback") public String getUserId(String name) { System.out.println(Thread.currentThread().getName()); int i = 1/0; //此处抛异常，测试服务降级 return "hellow:" + name; } public String helloFallback(String name) { return "error" + name; } //异步的执行 @HystrixCommand(fallbackMethod = "getUserNameError") public Future<String> getUserName(final Long id, String name) { return new AsyncResult<String>() { @Override public String invoke() { int i = 1/0;//此处抛异常,测试服务降级 return "你好:" + id; } }; } public String getUserNameError(Long id, String name) { return "触发熔断啦！！！！"; } }
二、HystrixCommand的非注解方式
import org.junit.Test; import rx.Observable; import rx.Observer; import rx.Subscription; import rx.functions.Action1; import java.util.concurrent.ExecutionException; import java.util.concurrent.Future; import static org.junit.Assert.assertEquals; /** * */ public class CommandHelloWorldTest { /** * 测试同步执行 */ @Test public void testSynchronous() { System.out.println(new CommandHelloWorld("World").execute()); } /** * 测试异步执行 */ @Test public void testAsynchronous() throws ExecutionException, InterruptedException { Future<String> fWorld = new CommandHelloWorld("World").queue(); System.out.println(fWorld.get()); //一步执行用get()来获取结果 } }
import com.netflix.hystrix.HystrixCommand; import com.netflix.hystrix.HystrixCommandGroupKey; import com.netflix.hystrix.HystrixCommandKey; import com.netflix.hystrix.HystrixRequestCache; import com.netflix.hystrix.strategy.concurrency.HystrixConcurrencyStrategyDefault; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.web.client.RestTemplate; /** * HystrixCommand用在命令服务返回单个操作结果的时候 */ public class CommandHelloWorld extends HystrixCommand<String> { private final String name; public CommandHelloWorld(String name) { super(HystrixCommandGroupKey.Factory.asKey("ExampleGroup")); this.name = name; } @Override protected String run() throws Exception { int i = 1/0; return "Hello " + name + "!"; } /** * 降级。Hystrix会在run()执行过程中出现错误、超时、线程池拒绝、断路器熔断等情况时， * 执行getFallBack()方法内的逻辑 */ @Override protected String getFallback() { return "faild"; } }
HystrixObservableCommand代码演示
import org.junit.Test; import rx.Observable; import java.util.Iterator; /** */ public class ObservableCommandHelloWorldTest { @Test public void testObservable() { Observable<String> observable= new ObservableCommandHelloWorld("World").observe(); Iterator<String> iterator = observable.toBlocking().getIterator(); while(iterator.hasNext()) { System.out.println(iterator.next()); } } @Test public void testToObservable() { Observable<String> observable= new ObservableCommandHelloWorld("World").observe(); Iterator<String> iterator = observable.toBlocking().getIterator(); while(iterator.hasNext()) { System.out.println(iterator.next()); } } }
import com.netflix.hystrix.HystrixCommandGroupKey; import com.netflix.hystrix.HystrixObservableCommand; import rx.Observable; import rx.Subscriber; import rx.schedulers.Schedulers; /** */ public class ObservableCommandHelloWorld extends HystrixObservableCommand<String> { private final String name; public ObservableCommandHelloWorld(String name) { super(HystrixCommandGroupKey.Factory.asKey("ExampleGroup")); this.name = name; } @Override protected Observable<String> construct() { return Observable.create(new Observable.OnSubscribe<String>() { @Override public void call(Subscriber<? super String> subscriber) { try { if(!subscriber.isUnsubscribed()) { subscriber.onNext("Hello"); int i = 1 / 0; //模拟异常 subscriber.onNext(name + "!"); subscriber.onCompleted(); } } catch (Exception e) { subscriber.onError(e); } } }).subscribeOn(Schedulers.io()); } /** * 服务降级 */ @Override protected Observable<String> resumeWithFallback() { return Observable.create(new Observable.OnSubscribe<String>() { @Override public void call(Subscriber<? super String> subscriber) { try { if (!subscriber.isUnsubscribed()) { subscriber.onNext("失败了！"); subscriber.onNext("触发熔断啦"); subscriber.onCompleted(); } } catch (Exception e) { subscriber.onError(e); } } }).subscribeOn(Schedulers.io()); } }
基于注解HystrixObservableCommand
package org.hope.hystrix.example.service; import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand; import com.netflix.hystrix.contrib.javanica.annotation.ObservableExecutionMode; import org.springframework.stereotype.Service; import rx.Observable; import rx.Subscriber; @Service public class ObservableUserService { /** * EAGER参数表示使用observe()方式执行 */ @HystrixCommand(observableExecutionMode = ObservableExecutionMode.EAGER, fallbackMethod = "observFailed") //使用observe()执行方式 public Observable<String> getUserById(final Long id) { return Observable.create(new Observable.OnSubscribe<String>() { @Override public void call(Subscriber<? super String> subscriber) { try { if(!subscriber.isUnsubscribed()) { subscriber.onNext("张三的ID:"); int i = 1 / 0; //抛异常，模拟服务降级 subscriber.onNext(String.valueOf(id)); subscriber.onCompleted(); } } catch (Exception e) { subscriber.onError(e); } } }); } private String observFailed(Long id) { return "observFailed---->" + id; } /** * LAZY参数表示使用toObservable()方式执行 */ @HystrixCommand(observableExecutionMode = ObservableExecutionMode.LAZY, fallbackMethod = "toObserbableError") //表示使用toObservable()执行方式 public Observable<String> getUserByName(final String name) { return Observable.create(new Observable.OnSubscribe<String>() { @Override public void call(Subscriber<? super String> subscriber) { try { if(!subscriber.isUnsubscribed()) { subscriber.onNext("找到"); subscriber.onNext(name); int i = 1/0; ////抛异常，模拟服务降级 subscriber.onNext("了"); subscriber.onCompleted(); } } catch (Exception e) { subscriber.onError(e); } } }); } private String toObserbableError(String name) { return "toObserbableError--->" + name; } }
package org.hope.hystrix.example.service; import org.hope.hystrix.example.HystrixApplication; import org.junit.Test; import org.junit.runner.RunWith; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.test.context.SpringBootTest; import org.springframework.test.context.junit4.SpringJUnit4ClassRunner; import java.util.Iterator; @RunWith(SpringJUnit4ClassRunner.class) @SpringBootTest(classes = HystrixApplication.class) public class ObservableUserServiceTest { @Autowired private ObservableUserService observableUserService; @Test public void testObserve() { Iterator<String> iterator = observableUserService.getUserById(30L).toBlocking().getIterator(); while(iterator.hasNext()) { System.out.println("===============" + iterator.next()); } } @Test public void testToObservable() { Iterator<String> iterator = observableUserService.getUserByName("王五").toBlocking().getIterator(); while(iterator.hasNext()) { System.out.println("===============" + iterator.next()); } } }
项目中大多情况下都是用使用基于注解 HystrixCommand，上边说了HystrixCommand使用的是异步，代码逻辑的执行是在新的线程中执行的，可是释放掉当前的主线程，可以更大程度的提升代码的并发
原文地址：https://www.cnblogs.com/happyflyingpig/p/8079308.html
