5.Hystrix实现Request Cache减压

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实现步骤如下

1.在下面创建RequestCacheService类

要点：
@CacheResult 把Friend 对象缓存起来
@CacheKey 唯一标识，把name当做获取Friend的唯一的key
@HystrixCommand 针对一个特定的服务要进行降级

• @HystrixCommand(commandKey = "cacheKey") 超时配置(简化Hystrix超时配置)，
  如：hystrix.command.cacheKey.execution.isolation.thread.timeoutInMilliseconds=3000 //MyService#retry(int)
• @HystrixCommand(commandKey = "fallbackMethod")，创建单独的降级方法，但是方法的参数必须和被注解的一致

RequestCacheService：

package com.imooc.springcloud.hystrix;

import com.imooc.springcloud.Friend;
import com.imooc.springcloud.MyService;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import com.netflix.hystrix.contrib.javanica.cache.annotation.CacheKey;
import com.netflix.hystrix.contrib.javanica.cache.annotation.CacheResult;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

/**
 * Created by 半仙.
 */
@Slf4j
@Service
public class RequestCacheService {

    @Autowired
    private MyService service;

    @CacheResult
    @HystrixCommand(commandKey = "cacheKey")
    public Friend requestCache(@CacheKey String name) {
        log.info("request cache " + name);
        Friend friend = new Friend();
        friend.setName(name);
        friend = service.sayHiPost(friend);
        log.info("after requesting cache " + name);
        return friend;
    }

}

2.调用RequestCacheService类中的requestCache方法

save的时候一直点击保存，RequestCacheService上下文可以让方法只被调用一次

• @Cleanup 使用 帮忙调用上下文的close方法，可不用try cache了 @Cleanup（“value”）?

package com.imooc.springcloud;

import com.imooc.springcloud.hystrix.RequestCacheService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class Controller {

    @Autowired
    private MyService myService;
    @Autowired
    private RequestCacheService requestCacheService;

    @GetMapping("/fallback")
    public String fallback(){
        return myService.error();
    }

    @GetMapping("/timeout")
    public String timeout(Integer timeout){
        return myService.retry(timeout);
    }

    @GetMapping("/cache")
    public Friend cache(String  name){
        Friend friend = requestCacheService.requestCache(name);

        return friend;
    }

}

3.配置文件

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4.测试缓存

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121?
1个上线文
2个注解@CacheResult @CacheKey
1个@HystrixCommand