CompletionService

最新推荐文章于 2025-03-10 01:18:48 发布

iteye_12959

最新推荐文章于 2025-03-10 01:18:48 发布

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分类专栏： J2EE 文章标签： Java thread Web

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本文介绍了一个使用Java并发包中的CompletionService接口的示例程序。该程序创建了一个固定大小的线程池并使用ExecutorCompletionService来管理异步任务的提交与获取。通过提交Callable任务并按完成顺序获取结果，演示了如何利用CompletionService处理并发任务。

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package thread;

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 TestCompletionService {
	  public static void main(String[] args) throws InterruptedException,
	      ExecutionException {
	    ExecutorService exec = Executors.newFixedThreadPool(10);
	    CompletionService<String> serv = 
	      new ExecutorCompletionService<String>(exec);

	    for (int index = 0; index < 5; index++) {
	      final int NO = index;
	      Callable<String> downImg = new Callable<String>() {
	        public String call() throws Exception {
	          Thread.sleep((long) (Math.random() * 10000));
	          return "Downloaded Image " + NO;
	        }
	      };
	      serv.submit(downImg);
	    }

	    Thread.sleep(1000 * 2);
	    System.out.println("Show web content");
	    for (int index = 0; index < 5; index++) {
	      Future<String> task = serv.take();
	      String img = task.get();
	      System.out.println(img);
	    }
	    System.out.println("End");
	    // 关闭线程池
	    exec.shutdown();
	  }
	}