Java—Callable，Future的使用

package cn.itcast.heima;

import java.util.Random;

import java.util.concurrent.Callable;

import java.util.concurrent.CompletionService;

import java.util.concurrent.ExecutionException;

import java.util.concurrent.ExecutorCompletionService;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

import java.util.concurrent.Future;

public class CallableAndFuture {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
ExecutorService threadpool = Executors.newSingleThreadExecutor();      //默认创建一个线程
Future<String> future = threadpool.submit(new Callable<String>(){
@Override
public String call() throws Exception {
// TODO Auto-generated method stub
Thread.sleep(2000);
return "hello";                  //返回的结果
}
});
System.out.println("等待结果");
try {
System.out.println("结果:"+future.get());
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ExecutionException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
ExecutorService threadPool2 =  Executors.newFixedThreadPool(10);                  //创建10个线程
CompletionService<Integer> completionService = new ExecutorCompletionService<Integer>(threadPool2);
for(int i=1;i<=10;i++){
final int seq = i;
completionService.submit(new Callable<Integer>() {
@Override
public Integer call() throws Exception {
Thread.sleep(new Random().nextInt(5000));
return seq;         //返回结果
}
});
}
for(int i=0;i<10;i++){
try {
System.out.println(
completionService.take().get());
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ExecutionException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}

效果图：