续：
Hystrix使用
1 package com.cjs.example;
2
3 import com.netflix.hystrix.HystrixCommand;
4 import com.netflix.hystrix.HystrixCommandGroupKey;
5
6 public class CommandHelloWorld extends HystrixCommand<String> {
7
8 private String name;
9
10 public CommandHelloWorld(HystrixCommandGroupKey group, String name) {
11 super(group);
12 this.name = name;
13 }
14
15 public CommandHelloWorld(Setter setter, String name) {
16 super(setter);
17 this.name = name;
18 }
19
20 @Override
21 protected String run() throws Exception {
22 if ("Alice".equals(name)) {
23 throw new RuntimeException("出错了");
24 }
25 return "Hello, " + name;
26 }
27
28 @Override
29 protected String getFallback() {
30 return "Failure, " + name;
31 }
32
33 }
1 package com.cjs.example;
2
3 import com.netflix.hystrix.HystrixCommand;
4 import com.netflix.hystrix.HystrixCommandGroupKey;
5 import com.netflix.hystrix.HystrixCommandProperties;
6 import com.netflix.hystrix.HystrixThreadPoolProperties;
7 import org.junit.Test;
8 import rx.Observable;
9 import rx.Observer;
10
11 import java.util.concurrent.ExecutionException;
12 import java.util.concurrent.Future;
13
14 import static org.junit.Assert.*;
15 import static org.junit.Assert.assertEquals;
16
17 public class CommandHelloWorldTest {
18
19 @Test
20 public void testSync() {
21 HystrixCommandGroupKey hystrixCommandGroupKey = HystrixCommandGroupKey.Factory.asKey("ExampleGroup");
22 CommandHelloWorld command = new CommandHelloWorld(hystrixCommandGroupKey, "World");
23 String result = command.execute();
24 assertEquals("Hello, World", result);
25 }
26
27 @Test
28 public void testAsync() throws ExecutionException, InterruptedException {
29 HystrixCommandGroupKey groupKey = HystrixCommandGroupKey.Factory.asKey("ExampleGroup");
30 assertEquals("Hello, Jack", new CommandHelloWorld(groupKey, "Jack").queue().get());
31 assertEquals("Hello, Rose", new CommandHelloWorld(groupKey, "Rose").queue().get());
32
33 CommandHelloWorld command = new CommandHelloWorld(groupKey, "Cheng");
34 Future<String> future = command.queue();
35 String result = future.get();
36 assertEquals("Hello, Cheng", result);
37
38 // blocking
39 Observable<String> observable = new CommandHelloWorld(groupKey, "Lucy").observe();
40 assertEquals("Hello, Lucy", observable.toBlocking().single());
41
42 // non-blocking
43 Observable<String> observable2 = new CommandHelloWorld(groupKey, "Jerry").observe();
44 observable2.subscribe(new Observer<String>() {
45 @Override
46 public void onCompleted() {
47 System.out.println("completed");
48 }
49
50 @Override
51 public void onError(Throwable throwable) {
52 throwable.printStackTrace();
53 }
54
55 @Override
56 public void onNext(String s) {
57 System.out.println("onNext: " + s);
58 }
59 });
60 }
61
62 @Test
63 public void testFail() throws ExecutionException, InterruptedException {
64 HystrixCommandGroupKey groupKey = HystrixCommandGroupKey.Factory.asKey("Group2");
65 assertEquals("Failure, Alice", new CommandHelloWorld(groupKey,"Alice").execute());
66 assertEquals("Failure, Alice", new CommandHelloWorld(groupKey,"Alice").queue().get());
67 }
68
69 @Test
70 public void testProp() {
71 HystrixCommandGroupKey groupKey = HystrixCommandGroupKey.Factory.asKey("Group3");
72
73 HystrixThreadPoolProperties.Setter threadPoolProperties = HystrixThreadPoolProperties.Setter()
74 .withCoreSize(10)
75 .withMaximumSize(10);
76
77 HystrixCommandProperties.Setter commandProperties = HystrixCommandProperties.Setter()
78 .withCircuitBreakerEnabled(true)
79 .withExecutionTimeoutInMilliseconds(100);
80
81 HystrixCommand.Setter setter = HystrixCommand.Setter.withGroupKey(groupKey);
82 setter.andThreadPoolPropertiesDefaults(threadPoolProperties);
83 setter.andCommandPropertiesDefaults(commandProperties);
84
85 assertEquals("Hello, Cheng", new CommandHelloWorld(setter, "Cheng").execute());
86
87 }
88 }
Spring Boot中使用Hystrix
1. Maven依赖
2. 使用@HystrixCommand注解
1 package com.cjs.example;
2
3 import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
4 import com.netflix.hystrix.contrib.javanica.annotation.HystrixProperty;
5 import org.apache.commons.lang.StringUtils;
6 import org.springframework.web.bind.annotation.RequestMapping;
7 import org.springframework.web.bind.annotation.RestController;
8
9 @RestController
10 @RequestMapping("/greet")
11 public class GreetController {
12
13 @HystrixCommand(fallbackMethod = "onError",
14 commandProperties = {
15 @HystrixProperty(name = "execution.isolation.strategy", value = "THREAD"),
16 @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "1000"),
17 @HystrixProperty(name = "circuitBreaker.enabled", value = "true"),
18 @HystrixProperty(name = "circuitBreaker.requestVolumeThreshold", value = "2")},
19 threadPoolProperties = {
20 @HystrixProperty(name = "coreSize", value = "5"),
21 @HystrixProperty(name = "maximumSize", value = "5"),
22 @HystrixProperty(name = "maxQueueSize", value = "10")
23 })
24 @RequestMapping("/sayHello")
25 public String sayHello(String name) {
26 try {
27 Thread.sleep(200);
28 } catch (InterruptedException e) {
29 e.printStackTrace();
30 }
31 return "Hello, " + name;
32 }
33
34 @HystrixCommand
35 @RequestMapping("/sayHi")
36 public String sayHi(String name) {
37 if (StringUtils.isBlank(name)) {
38 throw new RuntimeException("name不能为空");
39 }
40 return "Good morning, " + name;
41 }
42
43 /**
44 * 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
45 */
46 public String onError(String name) {
47 return "Error!!!" + name;
48 }
49
50 }
3. Hystrix配置
1 package com.cjs.example;
2
3 import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
4 import com.netflix.hystrix.contrib.javanica.aop.aspectj.HystrixCommandAspect;
5 import com.netflix.hystrix.contrib.metrics.eventstream.HystrixMetricsStreamServlet;
6 import org.springframework.boot.web.servlet.ServletContextInitializer;
7 import org.springframework.boot.web.servlet.ServletRegistrationBean;
8 import org.springframework.context.annotation.Bean;
9 import org.springframework.context.annotation.Configuration;
10
11 import javax.servlet.Servlet;
12
13 @Configuration
14 public class HystrixConfig {
15
16 /**
17 * A {@link ServletContextInitializer} to register {@link Servlet}s in a Servlet 3.0+ container.
18 */
19 @Bean
20 public ServletRegistrationBean hystrixMetricsStreamServlet() {
21 return new ServletRegistrationBean(new HystrixMetricsStreamServlet(), "/hystrix.stream");
22 }
23
24 /**
25 * AspectJ aspect to process methods which annotated with {@link HystrixCommand} annotation.
26 *
27 * {@link HystrixCommand} annotation used to specify some methods which should be processes as hystrix commands.
28 */
29 @Bean
30 public HystrixCommandAspect hystrixCommandAspect() {
31 return new HystrixCommandAspect();
32 }
33
34 }
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