AsyncFuntion接口与之前学习吃的使用Function和Functions进行对象转换有很密切的联系，AsyncFuction接口是Function接口的异步表现，AsyncFuction和Function都需要接收一个input参数，不同的是AsyncFunction接口返回的是 ListenableFuture，当我们需要接收AsyncFunction转换后的结果时，我们需要调用 ListenableFuture.get()方法。

AsyncFunction接口常被用于当我们想要异步的执行转换而不造成线程阻塞时，尽管Future.get()方法会在任务没有完成时造成阻塞，但 是AsyncFunction接口并不被建议用来异步的执行转换，它常被用于返回Future实例。

import java.util.concurrent.Callable;

import java.util.concurrent.ExecutionException;

import java.util.concurrent.Executors;

import com.google.common.util.concurrent.AsyncFunction;

import com.google.common.util.concurrent.Futures;

import com.google.common.util.concurrent.ListenableFuture;

import com.google.common.util.concurrent.ListeningExecutorService;

import com.google.common.util.concurrent.MoreExecutors;

public class AsyncFunctionTest {

private static ListeningExecutorService listeningExecutorService =

MoreExecutors.listeningDecorator(Executors.newFixedThreadPool(2));

static AsyncFunction<String, String> asyncFunction = new AsyncFunction<String, String>() {

@Override

public ListenableFuture<String> apply(final String input) throws Exception {

return listeningExecutorService.submit(new Callable<String>() {

@Override

public String call() throws Exception {

return input + "101";

}

});

}

};

static ListenableFuture<String> lis = listeningExecutorService.submit(new Callable<String>() {

@Override

public String call() throws Exception {

return "张三";

}

});

public static void main(String[] args) throws InterruptedException, ExecutionException {

ListenableFuture<String> lf =

Futures.transform(lis, asyncFunction);

System.out.println(lf.get());

listeningExecutorService.shutdown();

}

}