Java Callable并发编程模板

Posted 2020-08-30 TopCoderのZeze

submit方法会产生Future对象，它用Callable返回结果的特定类型进行了参数化，可以用isDone()的方法来查询Future是否已经完成。当任务完成是，它具有一个结果，可以调用get()方法来获取该结果。

/**   
* @Title: TaskWithResult.java 
* @Package zeze 
* @Description: TODO(用一句话描述该文件做什么) 
* @author A18ccms A18ccms_gmail_com   
* @date 2017年2月8日 上午10:51:26 
* @version V1.0   
*/
package zeze;

import java.util.ArrayList;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

public class CallableDemo {
    public static void main(String[] args) {
        ExecutorService exec = Executors.newCachedThreadPool();
        ArrayList<Future<String>> results = new ArrayList<Future<String>>();
        for (int i = 0; i < 10; i++) {
            results.add(exec.submit(new TaskWithResult(i)));
        }
        for (Future<String> fs : results) {
            try {
                System.out.println(fs.get());
            } catch (Exception e) {
                System.err.println(e);
            } finally {
                exec.shutdown();
            }
        }

    }
}

class TaskWithResult implements Callable<String> {

    private int id;

    public TaskWithResult(int id) {
        this.id = id;
    }

    @Override
    public String call() {
        return "result of TaskWithResult " + id;
    }

}

用isDone()的方法来查询Future是否已经完成

boolean isDone = false;
        while (!isDone) {
            logger.info(Thread.currentThread().getName() + " 线程是否结束?"+ runningFlag+"; 队列大小=" + nextDepthQueue.size());
            isDone = true;
            for (Future<Object> future : futureList) {
                if (!future.isDone()) {
                    isDone = false;
                    try {
                        Thread.sleep(3000);
                    } catch (InterruptedException e) {
                    }
                    break;
                }
            }
        }