SpringCloud（10）：Hystrix请求缓存

1 类继承的方法来实现请求缓存

1.1 编写CacheCommand类

package com.study.service.hystrix;

import com.netflix.hystrix.HystrixCommand;
import com.netflix.hystrix.HystrixCommandGroupKey;
import com.netflix.hystrix.HystrixCommandKey;
import com.netflix.hystrix.HystrixRequestCache;
import com.netflix.hystrix.strategy.concurrency.HystrixConcurrencyStrategyDefault;
import org.springframework.web.client.RestTemplate;

public class CacheCommand extends HystrixCommand<String> {

    private Long cacheKey;
    private RestTemplate restTemplate;
    private Integer uid;

    public CacheCommand(Long cacheKey, RestTemplate restTemplate, Integer uid) {
        super(Setter.withGroupKey(
                HystrixCommandGroupKey.Factory.asKey("cache-group")).andCommandKey(HystrixCommandKey.Factory.asKey("cache-test")));
        this.restTemplate = restTemplate;
        this.uid = uid;
        this.cacheKey = cacheKey;
    }

    @Override
    protected String run() throws Exception {
        System.out.println("没有缓存，查询数据~！");
        String url = "http://study-user/user/{id}";
        String info = restTemplate.getForObject(url, String.class, uid);
        return info;
    }

    @Override
    protected String getCacheKey() {
        return String.valueOf(cacheKey);
    }

    //清空缓存
    public void clearRequestCache(){
        HystrixRequestCache.getInstance(
                HystrixCommandKey.Factory.asKey("cache-test"), HystrixConcurrencyStrategyDefault.getInstance())
                .clear(String.valueOf(cacheKey));
    }
}

1.2 在OrderService中添加getUser2方法

    // 继承类的方式
    public String getUser2(Integer id) {

        Long cacheKey = 9999L;
        CacheCommand cacheCommand = new CacheCommand(9999L, restTemplate, id);
        String val = cacheCommand.execute();


        return val;
    }

1.3 在OrderContoller中编写测试接口

    @RequestMapping("/cache")
    public String cache() {
        HystrixRequestContext context = HystrixRequestContext.initializeContext();

        // 调用用户，查询用户信息，
        String result1 = orderService.getUser2(1);
        String result2 = orderService.getUser2(2);

        context.close();

        return "result1：" + result1 + "，result2：" + result2;
    }

访问接口测试，可以发现，在cachekey相同的情况下，返回的值是相同的

如果需要不同时，直接修改cachekey可以获取，如：

修改getUser2为

    // 继承类的方式
    public String getUser2(Integer id) {

        Long cacheKey = 9999L+id;
        CacheCommand cacheCommand = new CacheCommand(9999L, restTemplate, id);
        String val = cacheCommand.execute();


        return val;
    }

也可以直接调用清理缓存的方法，如下：

    public String getUser2(Integer id) {

        Long cacheKey = 9999L;
        CacheCommand cacheCommand = new CacheCommand(9999L, restTemplate, id);
        String val = cacheCommand.execute();

        // 清空request缓存
        cacheCommand.clearRequestCache();

        return val;
    }

2 注解方式实现请求缓存

2.1 在OrderService中添加getUser3方法以及clearRequestCache方法

    //请求缓存注解
    @CacheResult
    @HystrixCommand(commandKey = "cache-user")
    public String getUser3(Integer id, @CacheKey Long cacheKey) {
        String url = "http://study-user/user/{id}";
        String info = restTemplate.getForObject(url, String.class, id);
        return info;
    }

    //缓存清除注解
    @CacheRemove(commandKey = "cache-user")
    @HystrixCommand
    public void clearRequestCache(@CacheKey Long cacheKey) {
    }

2.2 在OrderContoller中编写测试接口

    @RequestMapping("/cache2")
    public String cache2() {
        HystrixRequestContext context = HystrixRequestContext.initializeContext();

        // 调用用户，查询用户信息，
        String result1 = orderService.getUser3(1, 12345L);
        String result2 = orderService.getUser3(2, 12345L);

        context.close();

        return "cache2 result1：" + result1 + "， cache2 result2：" + result2;
    }

如果要清除缓存，直接调用clearRequestCache方法。