Java Design Demo -简单的队列-异步多任务队列（java android）

最新推荐文章于 2025-02-26 21:00:51 发布

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最新推荐文章于 2025-02-26 21:00:51 发布

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本文链接：https://blog.youkuaiyun.com/b275518834/article/details/8577141

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Demo代码下载地址

简单的单线程队列 -- 工作的时候遇到劣质打印机。给打印机发消息，打印机就会打印，如果在打印机还在打印的时候，就

再发消息打印，就会出现消息丢失。所以需要给上一个任务一些处理的间隔时间.

单线程的消息队列示例

package demo1;

import java.util.LinkedList;

public class Main {

	/**
	 * @param args
	 */

	private static Thread thread;
	private static LinkedList<Runnable> list = new LinkedList<Runnable>();

	static int test = 0;

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		final long time = System.currentTimeMillis();
		for (int i = 0; i < 20; i++) {

			tastEvent(new Runnable() {
				public void run() {


						try {
							Thread.sleep(500);
						} catch (InterruptedException e) {
							// TODO Auto-generated catch block
							e.printStackTrace();
						}

						System.out
								.println("第"
										+ (++test)
										+ ("个任务  耗时:" + (System
												.currentTimeMillis() - time)));
					}

			});
		}
	}

	public static void tastEvent(Runnable r) {
		synchronized (list) {
			list.add(r);
		}
			if (thread == null) {
				thread = new Thread(run);
				thread.start();
			}


	}

	static Runnable run = new Runnable() {

		@Override
		public void run() {
			// TODO Auto-generated method stub
			synchronized (list) {

				while (!list.isEmpty()) {
					// new Thread(list.poll()).start();
					list.poll().run();
				}
				thread = null;
			}
		}
	};

}

工作的时候遇到非常大的并发的情况，比如机器1秒只支持1000的并发，但是1秒接收了4000的并发。服务器就会崩掉。

最好将并发放到队列中，按1000的并发吞吐量来处理，这就是异步队列应用。

一个工程交给一个人做，需要花费3个月，交给2个人做，需要2个人做需要2个月，需要3个人做需要1个月半.....100.人.....1000人,几年也完不成。

带上以上道理看待以下的代码

观察以下代码（复制到android工程下运行）：最后耗时约1600毫秒而使用android的AsyncTask类来改写这段代码只需要耗时约200

		final long	timer=System.currentTimeMillis();
		count=0;
		final Handler h=new Handler();
		for(int k=0;k<100;k++){
		new Thread(){
			@Override
			public void run() {
				// TODO Auto-generated method stub
				try {
					Thread.sleep(10);
				} catch (InterruptedException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
				h.post(new Runnable() {
					@Override
					public void run() {
						Toast.makeText(getApplicationContext()," 耗时"+ (System.currentTimeMillis() - timer), 1).show();
						System.err.println("编号"+(count++)+"线程消耗了"+(System.currentTimeMillis()-timer));
					}
				});
			}
		}.start();

可见增加多线程不提高性能，反而因为系统在不同的线程之间切换降低效率。因此我们需要让线程有序执行任务

以下是异步多线程处理队列的demo

package demo2;

import demo2.Task.OnFinishListen;

public class Main {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		
		Task.setThreadMaxNum(3);
		for (int i = 0; i < 15; i++) {
			new Task() {

				@Override
				public Object obtainData(Task task, Object parameter)
						throws Exception {
					// TODO Auto-generated method stub
					Thread.sleep(500);
					return task.taskID;
				}

			}
			.setOnFinishListen(new OnFinishListen() {

				@Override
				public void onFinish(Task task, Object data) {
					// TODO Auto-generated method stub
					System.err.println("任务编号"+task.taskID+"任务完成");
				}
			})
			.setTaskID(i)
			.start();
		}
	}

}

package demo2;

import java.util.HashMap;

import java.util.Map;
import java.util.Observable;
import java.util.Observer;

public abstract class Task<P,R> implements Runnable, Observer,TaskAction<P,R>{

	

	
	//设置最大任务数
	public static void setThreadMaxNum(int num) {
		TaskQueue.ThreadMaxNum = num<1?1:num>100?100:num;
	}

	
	
	public static enum TaskPriority {
		max, min;
	}

	/** 单例 可以提高性能 */
	protected final static Exception withoutException = new Exception(
			"The state is without");

	// 名字映射
	private static HashMap<String, Task> nameTasks;

	public static HashMap<String, Task> getNameTask() {
		if (nameTasks == null) {
			nameTasks = new HashMap<String, Task>();
		}
		return nameTasks;

	}

	public Task<P,R> setSingletonName(String singletonName) {
		this.singletonName = singletonName;
		return this;
	}

	public String getSingletonName() {
		return singletonName;
	}

	public interface OnStartListen {
		void onStart(Task t);
	}

	public interface OnProgressListen {
		void onProgress(Task task, int progress, Object data);
	}

	public static interface OnFinishListen<P,R> {
		void onFinish(Task<P,R> task, R data);
	}

	public interface OnSystemStartListen {
		void onSystemStart(Task task);
	}

	public interface OnSystemFinishListen {
		void OnSystemFinish(Task t, Object data);
	}

	

	/** 请求参数 */
	protected P parameter;
	/** 任务开始监听 */
	protected OnStartListen onStartListen;
	/** 任务进度监听 */
	protected OnProgressListen onProgressListen;
	/** 任务完成监听 */
	protected OnFinishListen<P,R> onFinishListen;
	/** 任务在队列中完成 监听 */
	protected OnSystemStartListen onSystemStartListen;
	/** 任务在队列中开始 监听 */
	protected OnSystemFinishListen onSystemFinishListen;
	/** 用于任务完成后发送消息 */
	/** 结果 */
	protected R result;
	/** 任务编号标示 */
	protected int taskID = -1;
	/** 任务名字标示 */
	/** 设置此任务名是否为单例，单例模式下，如果相同名字的任务未执行完，则无法添加新任务 */
	protected String singletonName;

	/** 保存一个对象 */
	protected Object tag;
	/** 获得当前自身线程的引用 在threadRun方法 */
	protected Thread thread;
	/** 重连次数 */
	protected int tryAgainCount = 1;
	/** 重连间隔 */
	protected int tryAgainTime = 1000;



	/** 默认优先级低 */
	protected TaskPriority priority = TaskPriority.min;


	protected HashMap<String,Object> dataMap;
	

	protected Task() {
	}



	// 任务状态
	public static enum TaskStatus {
		// 未处理 出错 完成 执行中 排除
		untreated, wait,error, finsh, running, without;
	}

	/** 状态 */
	TaskStatus status = TaskStatus.untreated;

	public void setWithout() {
		this.status = TaskStatus.without;
	}

	public void remove() {
		this.status = TaskStatus.without;
	}

	public TaskPriority getPriority() {
		return priority;
	}

	public void setPriority(TaskPriority priority) {
		this.priority = priority;
	}


	
	/** 启动线程 */
	public void start() {
		if (this.priority == null)
			this.priority = TaskPriority.min;
		
		synchronized (TaskQueue.tasks_wait) {
			if (getSingletonName() != null
					&& Task.getNameTask().get(this.getSingletonName()) != null) {
				this.setWithout();
			} else {
				Task.getNameTask().put(this.getSingletonName(), this);

			}

			switch (priority) {
			case min:
				TaskQueue.tasks_wait.remove(this);
				TaskQueue.tasks_wait.add(this);
				break;
			case max:
				TaskQueue.tasks_wait.remove(this);
				TaskQueue.tasks_wait.addFirst(this);
				break;
			default:
				break;
			}
			// 启动此服务
			TaskQueue.serivesRun();
		}
		
	}

	/** 启动线程 */
	public void start(TaskPriority priority) {
		
		
		this.priority = priority;
		status=TaskStatus.wait;
		start();
	}


	/** 启动线程 */
	final void threadRun() {
		thread = new Thread(this);
		thread.start();
	}

	// 中断Execute方法
	public  void shutDownExecute(){};

	public  R cacheData(P parameter){
		return result;};

	// 禁止被重写
	public final Object Execute() throws Exception {
		// TODO Auto-generated method stub
		if (onStartListen != null)
			onStartListen.onStart(this);

		// 队列中回调
		if (onSystemStartListen != null)
			onSystemStartListen.onSystemStart(this);
		// 状态从未处理改变为处理中
		status = TaskStatus.running;

		// 获取最后一次是否错误
		Exception exception = null;
		// 是否有缓存数据如果没有
		if ((result = cacheData(parameter)) == null) {

			// 失败重联次数
			for (int i = 0; i < tryAgainCount; i++) {
				try {
					// 如果状态改变为排除则跳出失败重联
					if (status == TaskStatus.without) {
						break;
					}
					exception = null;
					result = obtainData(this, parameter);
					System.out.println("result=" + result);
					break;
				} catch (Exception e) {
					// TODO Auto-generated catch block
					if ((exception = e) == withoutException) {
						break;
					}
					e.printStackTrace();
					try {
						Thread.sleep(tryAgainTime);
					} catch (Exception e1) {
						// TODO Auto-generated catch block
						e1.printStackTrace();
					}
				}
			}
		}
		// 如果最后一次仍然失败则抛出
		if (exception != null) {
			throw exception;
		}


		// 如果状态改变为处理完但不通知
		if (status != TaskStatus.without) {

			if (onFinishListen != null) {
				//完成监听并将结果加入到主线程
				onFinishListen.onFinish(this, result);
			}
			;


		}
		if (onSystemFinishListen != null) {
			onSystemFinishListen.OnSystemFinish(this, result);
		}
		status = TaskStatus.finsh;
		return result;
	}

	public abstract  R obtainData(Task<P,R> task, P parameter)throws Exception;

	@Override
	public void update(Observable observable, Object data) {
		// 移除观察
		observable.deleteObserver(this);
		// 中断 停止关闭连接
		this.shutDownExecute();
		this.setWithout();
		if (this.thread != null) {
			this.thread.interrupt();
		}
		// 错误尝试次数为0
		this.tryAgainCount = 0;
	};

	@Override
	public void run() {

		try {
			Execute();
		} catch (Exception e) {
			e.printStackTrace();
			status = TaskStatus.error;


			
			// 如果状态改变为处理完但不通知
			if (status != TaskStatus.without) {
				
				if (onFinishListen != null) {
					//将结果加入到主线程
					onFinishListen.onFinish(this, result);
				}

			}
			if (onSystemFinishListen != null) {
				onSystemFinishListen.OnSystemFinish(this, e);
			}
		}

		//递归 避免新开线程   唤醒等待中的任务 
		TaskQueue.getRunnable().notifyWaitingTask();
		
	}



	public Object getTag() {
		return tag;
	}

	public Task setTag(Object tag) {
		this.tag = tag;
		return this;
	}

	public Thread getThread() {
		return thread;
	}

	public TaskStatus getStatus() {
		return status;
	}

	public Object getParameter() {
		return parameter;
	}

	public Task setParameter(P parameter) {
		this.parameter = parameter;
		return this;
	}

	public OnStartListen getOnStartListen() {
		return onStartListen;
	}

	public Task setOnStartListen(OnStartListen onStartListen) {
		this.onStartListen = onStartListen;
		return this;
	}

	public OnProgressListen getOnProgressListen() {
		return onProgressListen;
	}

	public Task setOnProgressListen(OnProgressListen onProgressListen) {
		this.onProgressListen = onProgressListen;
		return this;
	}

	public OnFinishListen getOnFinishListen() {
		return onFinishListen;
	}

	public Task setOnFinishListen(OnFinishListen onFinishListen) {
		this.onFinishListen = onFinishListen;
		return this;
	}

	public OnSystemStartListen getOnSystemStartListen() {
		return onSystemStartListen;
	}

	public OnSystemFinishListen getOnSystemFinishListen() {
		return onSystemFinishListen;
	}

	public void setOnSystemFinishListen(
			OnSystemFinishListen onSystemFinishListen) {
		this.onSystemFinishListen = onSystemFinishListen;
	}


	public int getTaskID() {
		return taskID;
	}

	public Task setTaskID(int taskID) {
		this.taskID = taskID;
		return this;
	}

	public Object getResult() {
		return result;
	}

	public int getTryAgainCount() {
		return tryAgainCount;
	}

	public Task setTryAgainCount(int tryAgainCount) {
		this.tryAgainCount = tryAgainCount;
		return this;
	}

	public int getTryAgainTime() {
		return tryAgainTime;
	}

	private Task setTryAgainTime(int tryAgainTime) {
		this.tryAgainTime = tryAgainTime;
		return this;
	}

	

	public Object  put(String key,Object value) {
		if(dataMap==null)
		{
			dataMap=new HashMap<String, Object>();
		}
		return dataMap.put(key, value);
	}
	public Object  get(String key,Object value) {
		if(dataMap==null)
		{
			dataMap=new HashMap<String, Object>();
		}
		return dataMap.get(key);
	}

	
  
}

package demo2;

import java.util.AbstractCollection;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;
import java.util.Random;

import demo2.Task.OnSystemFinishListen;
import demo2.Task.TaskStatus;


public class TaskQueue implements Runnable, OnSystemFinishListen {
	static String debug = "TaskQueue";
	@SuppressWarnings("unchecked")
	// 在等待的任务队列
	 static LinkedList<Task> tasks_wait = new LinkedList<Task>();

	public static class TaskQueueExpection extends Exception{
		TaskQueueExpection(String detailMessage) {
			super(detailMessage);
			// TODO Auto-generated constructor stub
		}
		
	};
	
	// 正在执行的任务
	 static ArrayList<Task> tasks_running = new ArrayList<Task>();
	// 是否持续运行
	public static boolean isRun=true;
	// runnable保证线程安全
	private static TaskQueue runnable = new TaskQueue();;
	// 最大线程数
	static int ThreadMaxNum = 1;

	public static TaskQueue getRunnable() {
		return runnable;
	}

	// 如果队列线程为空或者停止则重新开启
	public static void serivesRun() {
		// TODO Auto-generated method stub
		boolean isCanSeriver=false;
		synchronized (tasks_running) {
			isCanSeriver=tasks_running.size() < ThreadMaxNum;
		}
       runnable.run();
	}
	
	//获取正在执行的任务数
	public static int getRunningTaskCount() {
		synchronized (TaskQueue.tasks_running) {
			return TaskQueue.tasks_running.size();
		}
	}
	//设置最大任务数
	public static void setThreadMaxNum(int num) {
		TaskQueue.ThreadMaxNum = num<1?1:num>100?100:num;
	}

	// 线程锁 如果等待队列的任务数不为空，并且当前线程数字少于最大线程数
	public static boolean taskRun() {
		synchronized (tasks_wait) {
			synchronized (tasks_running) {
				return !tasks_wait.isEmpty()
						&& tasks_running.size() < ThreadMaxNum;
			}
		}
	}
    //开启新线程
	public void run() {
		// 线程锁 如果等待队列的任务数不为空，并且当前线程数字少于最大线程数
        Task newTask;
		while((newTask=getWaittingTask())!=null)
		{
			System.err.println("开启新线程处理一个新任务，ID："+newTask.getTaskID());
			newTask.setOnSystemFinishListen(runnable);
			newTask.threadRun();
			newTask=null;
		}
       
	}
	
	 //递归 避免新开线程   唤醒等待中的任务 但此方案会造成java.lang.StackOverflowError
	 void notifyWaitingTask()
	{
		Task newTask;
		while((newTask=getWaittingTask())!=null)
		{
			System.err.println("唤醒旧线程处理一个新任务，ID："+newTask.getTaskID());
			newTask.setOnSystemFinishListen(runnable);
			newTask.run();
			newTask=null;
		}
		
	}
	
	private  Task getWaittingTask()
	{
		Task t=null;
		//测试
		while (isRun && taskRun()) {
			// 添加带执行中动态数组中
			synchronized (tasks_wait) {
				// 从等待任务的队列中获取并移除此列表的头（第一个元素）
				t = tasks_wait.poll();
				// 如果h为空则从队列重新取对象或者任务绑定的状态变化了
				if (t == null || t.status == TaskStatus.without) {
					System.out.println("任务取消 编号" + t!=null?String.valueOf(t.getTaskID()):"空任务");
					continue;
				}
			}
			synchronized (tasks_running) {
				tasks_running.add(t);
			}
			System.out.println( "正在执行任务数" + tasks_running.size() + "/上限"
					+ ThreadMaxNum);

			return t;
		}
		return t;
	}
	

	@Override
	public void OnSystemFinish(Task t, Object data) {
		// TODO Auto-generated method stub
		synchronized (tasks_running) {
			// 从处理中的动态数组中移除此任务
			tasks_running.remove(t);
			System.out.println( "执行队列中移除任务taskid=" + t.taskID);
			// 通知执行后续未处理的任务
			System.out.println("正在执行任务数" + tasks_running.size() + "/上限"
					+ ThreadMaxNum);
           
			// 移除此名字映射
			if (t.getSingletonName() != null) {
				Task.getNameTask().remove(t.getSingletonName());
			}
		}
		

	}

}

Demo代码下载地址