wait和notify简单应用1

偏执的太偏执、 2022-05-25 12:08 159阅读 0赞

import java.util.ArrayList;
    import java.util.List;
    import java.util.Random;
    //一个线程去读取List的长度，如果List为空的时候，线程就wait，如果List中有值了，就notify去获取它的长度
    public class ListAwit {
    	private static List<Integer> list = new ArrayList<Integer>();
    	final static Random rand = new Random();
    	public static void main(String[] args) {
    		
    		final ListAwit la = new ListAwit();
    		
    		new Thread(new Runnable(){
    			public void run() {
    				while(true){
    					if(list.size() > 0){
    						synchronized(la){
    							la.notify();
    						}
    					}
    					sleep();
    				}
    			}})
    		.start();
    		while(true){
    			try {
    				System.out.println(Thread.currentThread().getName()+"等待.........");
    				synchronized(la){
    					la.wait();
    				}
    				sleep();
    			} catch (InterruptedException e) {
    				e.printStackTrace();
    			}
    			System.out.println(Thread.currentThread().getName()+"##长度:"+list.size());
    			System.out.println(list);
    		}
    	}
    	private static void sleep(){
    		try {
    			int randint = rand.nextInt(2000);
    			Thread.sleep(randint);
    			list.add(randint);
    			if(rand.nextInt(10)==5){
    				list.clear();
    			}
    		} catch (InterruptedException e) {
    			e.printStackTrace();
    		}
    	}
    	/**
    	 * 运行结果：
    	    main等待.........
    		main##长度:4
    		[289, 887, 41, 1192]
    		main等待.........
    		main##长度:8
    		[289, 887, 41, 1192, 1322, 238, 641, 1608]
    		main等待.........
    	 */
    }

实现一种类似信号控制的程序

public class SynchronizedMutex {
    	private Thread curOwner = null;
    	public synchronized void acquire() throws InterruptedException{
    		System.out.println("当前线程:"+Thread.currentThread().getName());
    		while(curOwner != null){
    			this.wait();
    		}
    		this.curOwner = Thread.currentThread();
    	}
    	public synchronized void release() throws InterruptedException{
    		System.out.println("当前线程:"+Thread.currentThread().getName());
    		while(curOwner == Thread.currentThread()){
    			this.curOwner = null;
    			this.notify();
    		}
    	}
    }

import java.util.Random;
    import java.util.concurrent.ExecutorService;
    import java.util.concurrent.Executors;
    import java.util.concurrent.Semaphore;
    import java.util.concurrent.TimeUnit;
    
    public class MutexTest{
    //	private Semaphore mutex = new Semaphore(1);
    	private SynchronizedMutex mutex = new SynchronizedMutex();
    	public static void main(String[] args) {
    		final MutexTest test = new MutexTest();
    		
    		Runnable task = new Runnable(){
    			@Override
    			public void run() {
    				while(true){
    					int i = new Random().nextInt(3);
    					switch(i){
    						case 0:test.add();
    						case 1:test.add1();
    						case 2:test.del();
    						default:test.add();
    					}
    				}
    			}
    		};
    		ExecutorService exec = Executors.newCachedThreadPool();
    		for(int i=0; i<5; i++){
    			exec.execute(task);
    		}
    	}
    	private static int value;
    	public void add(){
    		try {
    			mutex.acquire();
    			TimeUnit.SECONDS.sleep(1);
    			System.out.println(Thread.currentThread().getName()+"增一:"+ (++value));
    			mutex.release();
    		} catch (InterruptedException e) {
    			e.printStackTrace();
    		}
    	}
    	public void add1(){
    		try {
    			mutex.acquire();
    			TimeUnit.SECONDS.sleep(1);
    			value = value + 2;
    			System.out.println(Thread.currentThread().getName()+"增二:"+ value);
    			mutex.release();
    		} catch (InterruptedException e) {
    			e.printStackTrace();
    		}
    	}
    	public void del(){
    		try {
    			mutex.acquire();
    			TimeUnit.SECONDS.sleep(1);
    			System.out.println(Thread.currentThread().getName()+"减一:"+ (--value));
    			mutex.release();
    		} catch (InterruptedException e) {
    			e.printStackTrace();
    		}
    	}
    	/**
    	 * 运行结果：
    	 *  当前线程:pool-1-thread-2
    		当前线程:pool-1-thread-4
    		当前线程:pool-1-thread-5
    		当前线程:pool-1-thread-3
    		当前线程:pool-1-thread-1
    		pool-1-thread-2减一:-1
    		当前线程:pool-1-thread-2
    		当前线程:pool-1-thread-2
    		pool-1-thread-4增一:0
    		当前线程:pool-1-thread-4
    		当前线程:pool-1-thread-4
    		pool-1-thread-4增二:2
    		当前线程:pool-1-thread-4
    		当前线程:pool-1-thread-4
    		pool-1-thread-4减一:1
    		当前线程:pool-1-thread-4
    		当前线程:pool-1-thread-4
    		pool-1-thread-4增一:2
    		当前线程:pool-1-thread-4
    		当前线程:pool-1-thread-4
    		pool-1-thread-4减一:1
    		当前线程:pool-1-thread-4
    		当前线程:pool-1-thread-4
    	 */
    }