Hystrix请求熔断与服务降级

public class HelloServiceCommand extends HystrixCommand<String> {    private RestTemplate restTemplate;    protected HelloServiceCommand(HystrixCommandGroupKey group) {        
　　　　　　super(group);            }　　//服务调用    @Override    protected String run() throws Exception {        System.out.println(Thread.currentThread().getName());        return restTemplate.getForEntity("http://HELLO-SERVICE/hello",String.class).getBody();    }　　//服务降级时所调用的Fallback()    @Override    protected String getFallback() {        return "error";    }}

package hjc.consumer;import com.netflix.hystrix.HystrixCommand;import com.netflix.hystrix.HystrixCommandGroupKey;import org.springframework.web.client.RestTemplate;/** * Created by cong on 2018/5/9. */public class HelloServiceCommand extends HystrixCommand<String> {    private RestTemplate restTemplate;    protected HelloServiceCommand(String commandGroupKey,RestTemplate restTemplate) {        super(HystrixCommandGroupKey.Factory.asKey(commandGroupKey));        this.restTemplate = restTemplate;    }    @Override    protected String run() throws Exception {        System.out.println(Thread.currentThread().getName());        return restTemplate.getForEntity("http://HELLO-SERVICE/hello",String.class).getBody();    }    @Override    protected String getFallback() {        return "error";    }}

/** * Created by cong on 2018/5/8. */@RestControllerpublic class ConsumerController {        @Autowired    private HelloService helloService;    @Autowired    private  RestTemplate restTemplate;    @RequestMapping("/consumer")    public String helloConsumer() throws ExecutionException, InterruptedException {        HelloServiceCommand command = new HelloServiceCommand("hello",restTemplate);        String result = command.execute();        return result;
　　}
}

Future<String> queue = command.queue();return queue.get();

/** * Created by cong on 2018/5/9. */@Servicepublic class HelloService {    @Autowired    private RestTemplate restTemplate;    @HystrixCommand(fallbackMethod = "helloFallBack")    public String helloService() throws ExecutionException, InterruptedException {        Future<String> future = new AsyncResult<String>() {            @Override            public String invoke() {                return restTemplate.getForEntity("http://HELLO-SERVICE/hello",String.class).getBody();            }        };        return future.get();    }

　　public String helloFallBack(){
    　　return "error";
　　}

}

package hjc.consumer;import com.netflix.hystrix.HystrixCommandGroupKey;import com.netflix.hystrix.HystrixObservableCommand;import org.springframework.web.client.RestClientException;import org.springframework.web.client.RestTemplate;import rx.Observable;import rx.Subscriber;/** * Created by cong on 2018/5/10. */public class HelloServiceObserveCommand extends HystrixObservableCommand<String>{    private RestTemplate restTemplate;    protected HelloServiceObserveCommand(String commandGroupKey, RestTemplate restTemplate) {        super(HystrixCommandGroupKey.Factory.asKey(commandGroupKey));        this.restTemplate = restTemplate;    }    @Override    protected Observable<String> construct() {
　　　　　　//观察者订阅网络请求事件        return Observable.create(new Observable.OnSubscribe<String>() {            @Override            public void call(Subscriber<? super String> subscriber) {                try {                    if (!subscriber.isUnsubscribed()){                        System.out.println("方法执行....");                        String result = restTemplate.getForEntity("http://HELLO-SERVICE/hello", String.class).getBody();
　　　　　　　　　　　　　　//这个方法监听方法，是传递结果的，请求多次的结果通过它返回去汇总起来。                        subscriber.onNext(result);                        String result1 = restTemplate.getForEntity("http://HELLO-SERVICE/hello", String.class).getBody();
　　　　　　　　　　　　　　//这个方法是监听方法，传递结果的                        subscriber.onNext(result1);                        subscriber.onCompleted();                    }                } catch (Exception e) {                    subscriber.onError(e);                }            }        });    }　　//服务降级Fallback    @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("error");                        subscriber.onCompleted();                    }                } catch (Exception e) {                    subscriber.onError(e);                }            }        });    }}

/** * Created by cong on 2018/5/8. */@RestControllerpublic class ConsumerController {    @Autowired    private  RestTemplate restTemplate;    @RequestMapping("/consumer")    public String helloConsumer() throws ExecutionException, InterruptedException {        List<String> list = new ArrayList<>();        HelloServiceObserveCommand command = new HelloServiceObserveCommand("hello",restTemplate);        //热执行        Observable<String> observable = command.observe();        //冷执行//        Observable<String> observable =command.toObservable();　　　　//订阅        observable.subscribe(new Observer<String>() {
　　　　　　　　//请求完成的方法            @Override            public void onCompleted() {                System.out.println("会聚完了所有查询请求");            }　　　　　　            @Override            public void onError(Throwable throwable) {                throwable.printStackTrace();            }　　　　　　　　//订阅调用事件，结果会聚的地方，用集合去装返回的结果会聚起来。            @Override            public void onNext(String s) {                System.out.println("结果来了.....");                list.add(s);            }        });        return list.toString();    }}

/** * Created by cong on 2018/5/8. */@RestControllerpublic class ConsumerController {    @Autowired    private  RestTemplate restTemplate;    @RequestMapping("/consumer")    public String helloConsumer() throws ExecutionException, InterruptedException {        List<String> list = new ArrayList<>();        HelloServiceObserveCommand command = new HelloServiceObserveCommand("hello",restTemplate);        //热执行        Observable<String> observable = command.observe();        //冷执行//        Observable<String> observable =command.toObservable();
　　　　Thread.sleep(10000);　　　　//订阅        observable.subscribe(new Observer<String>() {　　　　　　　　//请求完成的方法            @Override            public void onCompleted() {                System.out.println("会聚完了所有查询请求");            }　　　　　　            @Override            public void onError(Throwable throwable) {                throwable.printStackTrace();            }　　　　　　　　//订阅调用事件，结果会聚的地方，用集合去装返回的结果会聚起来。            @Override            public void onNext(String s) {                System.out.println("结果来了.....");                list.add(s);            }        });        return list.toString();    }}

/**
 * Created by cong on 2018/5/9.
 */
@Service
public class HelloService {

    @Autowired
    private RestTemplate restTemplate;


    //多请求结果会聚的注解写法，调用还是跟手写会聚一样调用
    //ObservableExecutionMode.EAGER热执行  ObservableExecutionMode.LAZY冷执行
　　//还可以忽略某些异常避免出现服务降级，有时候某些异常出现，但是我们并不想服务降级，异常就异常吧。参数ignoreExceptions = XXX.class
　　//groupKey ="" ,threadPoolKey = "",这是线程隔离，比如我需要根据groupKey划分，如果还要对groupKey内的任务进一步划分，就要threadPoolKey，比如对groupKey组内进行
　　//读取数据的时候，是从缓存读，还是数据库读
　　//@CacheKey,缓存的注解方式

    @HystrixCommand(fallbackMethod = "helloFallBack",observableExecutionMode = ObservableExecutionMode.LAZY)
    public Observable<String> helloService() throws ExecutionException, InterruptedException {
        return Observable.create(new Observable.OnSubscribe<String>() {
            @Override
            public void call(Subscriber<? super String> subscriber) {
                try {
                    if (!subscriber.isUnsubscribed()){
                        String result = restTemplate.getForEntity("http://HELLO-SERVICE/hello", String.class).getBody();
                        subscriber.onNext(result);
                        String result1 = restTemplate.getForEntity("http://HELLO-SERVICE/hello", String.class).getBody();
                        subscriber.onNext(result1);
                        subscriber.onCompleted();
                    }
                } catch (Exception e) {
                    subscriber.onError(e);
                }
            }
        });
    }

    public String helloFallBack(){
        return "error";
    }

}

  @HystrixCommand(fallbackMethod = "XX降级方法",observableExecutionMode = ObservableExecutionMode.LAZY)    public String helloFallBack(Throwable throwable){
　　　　　//网络请求
　　　　　　........
　　　　        return "error";    }