SpringCloud熔断机制-ribbon结合hystrix

ribbon服务

1.pom依赖

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

2.配置

创建CommandForIndex类

public class CommandForIndex extends HystrixCommand<Object> {

    private final RestTemplate template;

    private String id;

    public CommandForIndex(String id, RestTemplate restTemplate) {
        // java代码配置， 只针对这个命令
        super(Setter
                // 必填项,用于统计,指定命令分组名
                .withGroupKey(HystrixCommandGroupKey.Factory.asKey("Hello-Group"))
                // 熔断配置依赖名称,默认值command实现类的类名(比如这个就是CommandForIndex),如果是服务调用,则写具体的接口名
                .andCommandKey(HystrixCommandKey.Factory.asKey("ConsumerController"))
                // 线程池配置依赖名称，默认值HystrixCommandGroupKey的名称
                .andThreadPoolKey(HystrixThreadPoolKey.Factory.asKey("User-ThreadPool"))
                // command 熔断相关参数配置
                .andCommandPropertiesDefaults(HystrixCommandProperties.Setter()
                                // 配置隔离方式：默认采用线程池隔离。(还有信号量隔离方式)
                                 .withExecutionIsolationStrategy(HystrixCommandProperties.ExecutionIsolationStrategy.SEMAPHORE)
                                // 超时时间500毫秒
                                .withExecutionTimeoutInMilliseconds(500)
                        // 信号量隔离的模式下，最大的请求数。和线程池大小的意义一样
                        // .withExecutionIsolationSemaphoreMaxConcurrentRequests(2)
                        // 熔断时间（熔断开启后，各5秒后进入半开启状态，试探是否恢复正常）
                        // .withCircuitBreakerSleepWindowInMilliseconds(5000)
                )
                // 设置线程池参数
                .andThreadPoolPropertiesDefaults(HystrixThreadPoolProperties.Setter()
                        // 线程池大小
                        .withCoreSize(1)
                        //允许最大的缓冲区大小
//                       .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结束#######" + Thread.currentThread().toString() + ">><>>>执行结果:" + result.toString());
        return result;
    }

    @Override
    protected Object getFallback() {
        System.out.println("###降级啦####" + Thread.currentThread().toString());
        return "出錯了，我降級了";
        //降级的处理：
        //1.返回一个固定的值
        //2.去查询缓存
        //3.调用一个备用接口
    }
}

测试

修改Controller层

@RestController
public class ConsumerController {

    @Autowired
    RestTemplate restTemplate;

    @GetMapping("")
    public Object index(@RequestParam("id")String id){
        //localhost:8001和http://helloclient等同 ,在配置文件中有相关配置
        //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 "查询超时啦，我降级了。";
    }
}

修改hello-demo和ribbon服务的application.yml,将服务注册到注册中心上去

server:
  port: 8092

###定义实例名
spring:
  application:
    name: spring-cloud-ribbon-consumer

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

修改hello-demo服务的controller层,将第一个hello-demo请求接口sleep一秒钟

	@GetMapping("user")
    public Object getUser(@Param("id")String id) throws InterruptedException {
        System.out.println("客户端1返回了请求");
        Thread.sleep(1000L);
        return helloService.get(id);
    }

启动服务
服务请求超时,服务降级

再次请求
请求成功

示例代码:
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