Hystrix服务降级实战

一、启动类添加注解

package com.ssm.sku;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.hystrix.EnableHystrix;
import org.springframework.context.annotation.ComponentScan;

@SpringBootApplication
@MapperScan(value = "com.ssm.*.mapper")
@ComponentScan(value = "com.ssm")
@EnableHystrix
public class SkuApplication {
    public static void main(String[] args) {
        System.setProperty("Log4jContextSelector", "org.apache.logging.log4j.core.async.AsyncLoggerContextSelector");
        SpringApplication.run(SkuApplication.class, args);
    }
}

二、提供方降级

@GetMapping("testHystrixTimeOut")
@HystrixCommand(fallbackMethod = "testHystrixTimeoutHandler", commandProperties = {
        @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "3000")
})
public String testHystrixTimeOut() throws InterruptedException {
    Thread.sleep(5000);
    return "Hello hystrix timeOut!";
}

public String testHystrixTimeoutHandler() {
    return "我降级了！！！";
}

参数解读：

• @HystrixCommand 声明该方法为是一个hystrix命令

• fallbackMethod 属性提供回退方法， 当方法执行失败时调用(如超时、异常等)

• commandProperties 属性可指定Hystrix命令的多个配置属性

• @HystrixProperty 每个配置都通过 @HystrixProperty 注解来定义，其中 name 属性指定了配置的名称，value 属性指定了配置的值

• execution.isolation.thread.timeoutInMilliseconds 隔离线程的超时，单位为毫秒。超过指定时间会调用回退方法

结果：

三、调用方降级

将sku微服务模块中的方法写到home微服务模块的feign中并在controller中提供方法调用

feign新增：

@GetMapping("testHystrix")
public String testHystrix();

@GetMapping("testHystrixTimeOut")
public String testHystrixTimeOut();

controller新增：

@GetMapping("getHystrixTimeOut")
@HystrixCommand(fallbackMethod = "testHystrixTimeoutHandler", commandProperties = {
        @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "1000")
})
public String testHystrixTimeOut() {
    return skuFeignService.testHystrixTimeOut();
}

public String testHystrixTimeoutHandler()  {
    return "主动降级了！!";
}

启动类添加@EnableHystrix注解

结果：