Android中的线程池与任务队列

Android中的线程池与任务队列:

            在Android手机开发的时候，考虑的资源问题是必须的。当然我们要注重线程的消耗资源的过程，线程在new的时候最消耗内存开销，而在运行的时候远远小于new的时候的内存开销。故我们可以考虑应用线程池与任务队列去解决线程的消耗问题。

 1.  DownloadTask.java：

package com.threadExecutorService.download;

public class DownloadTask implements Runnable {

	public String name;
	
	public DownloadTask(String name) {
		this.name = name;
	}
	
	@Override
	public void run() {
		try {
			Thread.sleep(1500);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		System.out.println(name + " executed OK!");  
	}
	
	public String getFileId(){  
        return name;  
    } 

}

package com.threadExecutorService.download;

import java.util.HashSet;
import java.util.LinkedList;
import java.util.Set;

/*
 * 其中downloadTasks表示的是线程队列，taskIdSet是任务队列，作用就是用来管理线程队列，此程序用的是去重操作。已经下载过的文件，不会再次下载。
 */
public class DownloadTaskManager {

	//请求线程队列
	private LinkedList<DownloadTask> downloadTasks;
	//任务不能重复
	private Set<String> taskIdSet;
	
	private static DownloadTaskManager downloadTaskManager;
	
	public static synchronized DownloadTaskManager getInstance(){
		if (null == downloadTaskManager) {
			downloadTaskManager = new DownloadTaskManager();
		}
		return downloadTaskManager;
	}
	
	private DownloadTaskManager() {
		downloadTasks = new LinkedList<DownloadTask>();
		taskIdSet = new HashSet<String>();
	}
	
	public void addDownloadTask(DownloadTask downloadTask){
		synchronized (downloadTasks) {
			if (!isTaskRepeat(downloadTask.getFileId())) {
				downloadTasks.addLast(downloadTask);
			}
		}
	}
	
	public boolean isTaskRepeat(String fileId) { 
		synchronized (taskIdSet) {
			if (taskIdSet.contains(fileId)) {
				return true;
			} else {
				System.out.println("下载管理器增加下载任务："+ fileId);  
				taskIdSet.add(fileId);
				return false;
			}
		}
	}
	
	public DownloadTask getDownloadTask() { 
		synchronized (downloadTasks) {
			if (downloadTasks.size() > 0) {
				System.out.println("下载管理器增加下载任务："+"取出任务");
				DownloadTask downloadTask = downloadTasks.removeFirst();
				return downloadTask;
			}
		}
		return null;
	}
	
}

DownloadTaskManagerThread.java

package com.threadExecutorService.download;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class DownloadTaskManagerThread implements Runnable{

	private DownloadTaskManager downloadTaskManager ;
	// 创建一个可重用固定线程数的线程池 
	private ExecutorService pool;
	// 线程池大小  
	private final int POOL_SIZE = 5;
	// 轮询时间
	private final int SLEEP_TIME = 1000;
	// 是否停止  
    private boolean isStop = false;
	
    public DownloadTaskManagerThread() {
		this.downloadTaskManager = DownloadTaskManager.getInstance();
		pool = Executors.newFixedThreadPool(POOL_SIZE);
	}
    
	@Override
	public void run() {
		while (!isStop) {
			DownloadTask downloadTask = downloadTaskManager.getDownloadTask();
			if (downloadTask != null) {
				pool.execute(downloadTask);
			} else {//如果当前任务队列中没有下载任务downloadTask
				try {
					// 查询任务完成失败的,重新加载任务队列  
                    // 轮询
					Thread.sleep(SLEEP_TIME);
				} catch (InterruptedException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
		}
		
		if (isStop) {
			pool.shutdown();
		}
		
		
	}
	
	public void setStop(boolean isStop) {  
        this.isStop = isStop;  
    } 

 }

package com.threadExecutorService.test;

import com.threadExecutorService.download.DownloadTask;
import com.threadExecutorService.download.DownloadTaskManager;
import com.threadExecutorService.download.DownloadTaskManagerThread;

public class Test {

	public static void main(String[] args) {
		//1.new一个线程管理队列  
		DownloadTaskManager downloadTaskManager = DownloadTaskManager.getInstance();  
        //2.new一个线程池，并启动  
        DownloadTaskManagerThread downloadTaskManagerThread = new DownloadTaskManagerThread();  
        new Thread(downloadTaskManagerThread).start();  
        
        //3.请求下载  
        String []items=new String[]{"阿凡达1","阿凡达2","阿凡达3","阿凡达4","阿凡达5","阿凡达6","阿凡达7","阿凡达1","阿凡达2"};  
  
        for (int i = 0; i < items.length; i++) {
        	downloadTaskManager.addDownloadTask(new DownloadTask(items[i]));
        	try {  
                Thread.sleep(2000);  
            } catch (InterruptedException e) {  
                e.printStackTrace();  
            }  
		}
        
        
	}

}

结果如下：

相同名字并不会继续执行，OK！

本文代码：http://download.csdn.net/detail/jdsjlzx/8454395