Spring Boot 集成 Hystrix

续：

《Hystrix介绍》

《Hystrix是如何工作的》

《SpringCloud学习笔记(3)——Hystrix》

Hystrix使用

 package com.cjs.example;

 import com.netflix.hystrix.HystrixCommand;
 import com.netflix.hystrix.HystrixCommandGroupKey;

 public class CommandHelloWorld extends HystrixCommand<String> {

     private String name;

     public CommandHelloWorld(HystrixCommandGroupKey group, String name) {
         super(group);
         this.name = name;
     }

     public CommandHelloWorld(Setter setter, String name) {
         super(setter);
         this.name = name;
     }

     @Override
     protected String run() throws Exception {
         if ("Alice".equals(name)) {
             throw new RuntimeException("出错了");
         }
         return "Hello, " + name;
     }

     @Override
     protected String getFallback() {
         return "Failure, " + name;
     }

 }

 package com.cjs.example;

 import com.netflix.hystrix.HystrixCommand;
 import com.netflix.hystrix.HystrixCommandGroupKey;
 import com.netflix.hystrix.HystrixCommandProperties;
 import com.netflix.hystrix.HystrixThreadPoolProperties;
 import org.junit.Test;
 import rx.Observable;
 import rx.Observer;

 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Future;

 import static org.junit.Assert.*;
 import static org.junit.Assert.assertEquals;

 public class CommandHelloWorldTest {

     @Test
     public void testSync() {
         HystrixCommandGroupKey hystrixCommandGroupKey = HystrixCommandGroupKey.Factory.asKey("ExampleGroup");
         CommandHelloWorld command = new CommandHelloWorld(hystrixCommandGroupKey, "World");
         String result = command.execute();
         assertEquals("Hello, World", result);
     }

     @Test
     public void testAsync() throws ExecutionException, InterruptedException {
         HystrixCommandGroupKey groupKey = HystrixCommandGroupKey.Factory.asKey("ExampleGroup");
         assertEquals("Hello, Jack", new CommandHelloWorld(groupKey, "Jack").queue().get());
         assertEquals("Hello, Rose", new CommandHelloWorld(groupKey, "Rose").queue().get());

         CommandHelloWorld command = new CommandHelloWorld(groupKey, "Cheng");
         Future<String> future = command.queue();
         String result = future.get();
         assertEquals("Hello, Cheng", result);

         //  blocking
         Observable<String> observable = new CommandHelloWorld(groupKey, "Lucy").observe();
         assertEquals("Hello, Lucy", observable.toBlocking().single());

         //  non-blocking
         Observable<String> observable2 = new CommandHelloWorld(groupKey, "Jerry").observe();
         observable2.subscribe(new Observer<String>() {
             @Override
             public void onCompleted() {
                 System.out.println("completed");
             }

             @Override
             public void onError(Throwable throwable) {
                 throwable.printStackTrace();
             }

             @Override
             public void onNext(String s) {
                 System.out.println("onNext: " + s);
             }
         });
     }

     @Test
     public void testFail() throws ExecutionException, InterruptedException {
         HystrixCommandGroupKey groupKey = HystrixCommandGroupKey.Factory.asKey("Group2");
         assertEquals("Failure, Alice", new CommandHelloWorld(groupKey,"Alice").execute());
         assertEquals("Failure, Alice", new CommandHelloWorld(groupKey,"Alice").queue().get());
     }

     @Test
     public void testProp() {
         HystrixCommandGroupKey groupKey = HystrixCommandGroupKey.Factory.asKey("Group3");

         HystrixThreadPoolProperties.Setter threadPoolProperties = HystrixThreadPoolProperties.Setter()
                 .withCoreSize(10)
                 .withMaximumSize(10);

         HystrixCommandProperties.Setter commandProperties = HystrixCommandProperties.Setter()
                 .withCircuitBreakerEnabled(true)
                 .withExecutionTimeoutInMilliseconds(100);

         HystrixCommand.Setter setter = HystrixCommand.Setter.withGroupKey(groupKey);
         setter.andThreadPoolPropertiesDefaults(threadPoolProperties);
         setter.andCommandPropertiesDefaults(commandProperties);

         assertEquals("Hello, Cheng", new CommandHelloWorld(setter, "Cheng").execute());

     }
 }

Spring Boot中使用Hystrix

1. Maven依赖

2. 使用@HystrixCommand注解

 package com.cjs.example;

 import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
 import com.netflix.hystrix.contrib.javanica.annotation.HystrixProperty;
 import org.apache.commons.lang.StringUtils;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RestController;

 @RestController
 @RequestMapping("/greet")
 public class GreetController {

     @HystrixCommand(fallbackMethod = "onError",
             commandProperties = {
                     @HystrixProperty(name = "execution.isolation.strategy", value = "THREAD"),
                     @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "1000"),
                     @HystrixProperty(name = "circuitBreaker.enabled", value = "true"),
                     @HystrixProperty(name = "circuitBreaker.requestVolumeThreshold", value = "2")},
             threadPoolProperties = {
                     @HystrixProperty(name = "coreSize", value = "5"),
                     @HystrixProperty(name = "maximumSize", value = "5"),
                     @HystrixProperty(name = "maxQueueSize", value = "10")
             })
     @RequestMapping("/sayHello")
     public String sayHello(String name) {
         try {
             Thread.sleep(200);
         } catch (InterruptedException e) {
             e.printStackTrace();
         }
         return "Hello, " + name;
     }

     @HystrixCommand
     @RequestMapping("/sayHi")
     public String sayHi(String name) {
         if (StringUtils.isBlank(name)) {
             throw new RuntimeException("name不能为空");
         }
         return "Good morning, " + name;
     }

     /**
      * 如果fallback方法的参数和原方法参数个数不一致，则会出现FallbackDefinitionException: fallback method wasn't found
      */
     public String onError(String name) {
         return "Error!!!" + name;
     }

 }

3. Hystrix配置

 package com.cjs.example;

 import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
 import com.netflix.hystrix.contrib.javanica.aop.aspectj.HystrixCommandAspect;
 import com.netflix.hystrix.contrib.metrics.eventstream.HystrixMetricsStreamServlet;
 import org.springframework.boot.web.servlet.ServletContextInitializer;
 import org.springframework.boot.web.servlet.ServletRegistrationBean;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;

 import javax.servlet.Servlet;

 @Configuration
 public class HystrixConfig {

     /**
      * A {@link ServletContextInitializer} to register {@link Servlet}s in a Servlet 3.0+ container.
      */
     @Bean
     public ServletRegistrationBean hystrixMetricsStreamServlet() {
         return new ServletRegistrationBean(new HystrixMetricsStreamServlet(), "/hystrix.stream");
     }

     /**
      * AspectJ aspect to process methods which annotated with {@link HystrixCommand} annotation.
      *
      * {@link HystrixCommand} annotation used to specify some methods which should be processes as hystrix commands.
      */
     @Bean
     public HystrixCommandAspect hystrixCommandAspect() {
         return new HystrixCommandAspect();
     }

 }

4. hystrix-dashboard

http://localhost:7979/hystrix-dashboard/

参考

https://github.com/Netflix/Hystrix/wiki/Configuration

https://github.com/Netflix/Hystrix/tree/master/hystrix-contrib/hystrix-metrics-event-stream

https://github.com/Netflix-Skunkworks/hystrix-dashboard