SpringCloud熔斷機制-ribbon結合hystrix

ribbon服務

1.pom依賴

		<dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
        </dependency>

2.配置

創建CommandForIndex類

public class CommandForIndex extends HystrixCommand<Object> {

    private final RestTemplate template;

    private String id;

    public CommandForIndex(String id, RestTemplate restTemplate) {
        // java代碼配置， 只針對這個命令
        super(Setter
                // 必填項,用於統計,指定命令分組名
                .withGroupKey(HystrixCommandGroupKey.Factory.asKey("Hello-Group"))
                // 熔斷配置依賴名稱,默認值command實現類的類名(比如這個就是CommandForIndex),如果是服務調用,則寫具體的接口名
                .andCommandKey(HystrixCommandKey.Factory.asKey("ConsumerController"))
                // 線程池配置依賴名稱，默認值HystrixCommandGroupKey的名稱
                .andThreadPoolKey(HystrixThreadPoolKey.Factory.asKey("User-ThreadPool"))
                // command 熔斷相關參數配置
                .andCommandPropertiesDefaults(HystrixCommandProperties.Setter()
                                // 配置隔離方式：默認採用線程池隔離。(還有信號量隔離方式)
                                 .withExecutionIsolationStrategy(HystrixCommandProperties.ExecutionIsolationStrategy.SEMAPHORE)
                                // 超時時間500毫秒
                                .withExecutionTimeoutInMilliseconds(500)
                        // 信號量隔離的模式下，最大的請求數。和線程池大小的意義一樣
                        // .withExecutionIsolationSemaphoreMaxConcurrentRequests(2)
                        // 熔斷時間（熔斷開啓後，各5秒後進入半開啓狀態，試探是否恢復正常）
                        // .withCircuitBreakerSleepWindowInMilliseconds(5000)
                )
                // 設置線程池參數
                .andThreadPoolPropertiesDefaults(HystrixThreadPoolProperties.Setter()
                        // 線程池大小
                        .withCoreSize(1)
                        //允許最大的緩衝區大小
//                       .withMaxQueueSize(2)
                ));
        // super(HystrixCommandGroupKey.Factory.asKey("User-command"),100);
        this.id = id;
        this.template = restTemplate;
    }

    @Override
    protected Object run() throws Exception {
        System.out.println("###command#######" + Thread.currentThread().toString());
        Object result =  template.getForObject("http://helloclient/user?id="+id+"",Object.class);
        System.out.println(
                "###command結束#######" + Thread.currentThread().toString() + ">><>>>執行結果:" + result.toString());
        return result;
    }

    @Override
    protected Object getFallback() {
        System.out.println("###降級啦####" + Thread.currentThread().toString());
        return "出錯了，我降級了";
        //降級的處理：
        //1.返回一個固定的值
        //2.去查詢緩存
        //3.調用一個備用接口
    }
}

測試

修改Controller層

@RestController
public class ConsumerController {

    @Autowired
    RestTemplate restTemplate;

    @GetMapping("")
    public Object index(@RequestParam("id")String id){
        //localhost:8001和http://helloclient等同 ,在配置文件中有相關配置
        //return restTemplate.getForObject("http://localhost:8001/user?id="+id+"",Object.class);
        //return restTemplate.getForObject("http://helloclient/user?id="+id+"",Object.class);
        return new CommandForIndex(id,restTemplate).execute();
    }

    @GetMapping("/get-teacher")
    public Object getTeacher(){
        //return restTemplate.getForEntity("http://localhost:8001",Teacher.class);
        return restTemplate.getForEntity("http://helloclient",Teacher.class);
    }

    public Object callTimeoutFallback(){
        return "查詢超時啦，我降級了。";
    }
}

修改hello-demo和ribbon服務的application.yml,將服務註冊到註冊中心上去

server:
  port: 8092

###定義實例名
spring:
  application:
    name: spring-cloud-ribbon-consumer

eureka:
  client:
    service-url:
      defaultZone: http://127.0.0.1:10000/eureka/

修改hello-demo服務的controller層,將第一個hello-demo請求接口sleep一秒鐘

	@GetMapping("user")
    public Object getUser(@Param("id")String id) throws InterruptedException {
        System.out.println("客戶端1返回了請求");
        Thread.sleep(1000L);
        return helloService.get(id);
    }

啓動服務
服務請求超時,服務降級

再次請求
請求成功

示例代碼:
碼雲