解決多線程並行加載緩存問題（利用guava實現）

依賴

com.google.guava:guava:20.0

 

import com.google.common.cache.Cache;
import com.google.common.cache.CacheBuilder;

import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

public class GuavaCache {
    static Cache<String, Object> cache = CacheBuilder.newBuilder()
            .expireAfterWrite(1000,TimeUnit.SECONDS)
            .maximumSize(1000)
            .build();
    public static void main(String[] args) {

        Runnable runnable = new Runnable(){

            @Override
            public void run() {
                Object cacheVal=null;
                try {
                    cacheVal = cache.get("a", GuavaCache::loadCache);
                } catch (ExecutionException e) {
                    e.printStackTrace();
                }
                System.out.println("thread:"+Thread.currentThread()+",拿到了緩存值："+cacheVal);
            }
        };

        ExecutorService pool = Executors.newFixedThreadPool(10);
        for (int i = 0; i < 10; i++) {
            pool.execute(runnable);
        }

        System.out.println("thread:"+Thread.currentThread()+",is end");

    }



    static Object loadCache(){
        System.out.println("開始耗時的緩存加載，thread:"+Thread.currentThread());
        try {
            Thread.sleep(100);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return "cache hui val";
    }
}