Loading Cache Asynchronous Reloading Test

LoadingCacheAsynchronousReloading.java

import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.ListenableFutureTask;
import org.junit.Test;

import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

public class CacheTest {

    @Test
    public void testLoadingCache() throws Exception {
        ExecutorService es = Executors.newFixedThreadPool(1);

        LoadingCache<String, String> cache = CacheBuilder.newBuilder()
                .refreshAfterWrite(1, TimeUnit.SECONDS)
                .build(new CacheLoader<String, String>() {
                    @Override
                    public String load(String s) throws Exception {
                        System.out.println(" start synchronous loading ");
                        return s + LocalDateTime.now().toString();
                    }

                    @Override
                    public ListenableFuture<String> reload(String s, String oldValue) {
                        System.out.println(" start asynchronous reloading ");
                        ListenableFutureTask<String> task = ListenableFutureTask.create(() -> {
                            try {
                                Thread.sleep(1000);
                            } catch (InterruptedException e) {

                            }
                            return s + LocalDateTime.now().toString();
                        });
                        task.addListener(() -> System.out.println("finish asynchronous reloading "), es);
                        es.submit(task);
                        return task;
                    }
                });

        for (int i=0; i< 10; i++) {
            String result = cache.get("1");
            System.out.println("result = " + result);
            Thread.sleep(500);
        }
    }
}