Java 线程间通讯

/*
线程间通讯：
多个线程在处理同一资源，但是任务却不同。
*/

package com.cwcec.test;

class Input implements Runnable
{
       Resource r;
       public Input(Resource r)
       {
           this.r = r;
       }
       public void run()
       {
           int x = 0;
           while(true)
           {
               synchronized (r)
               {
                   if(x == 0)
                      {
                          r.name = "Mike";
                          r.sex = "nan";
                      }
                      else
                      {
                       r.name = "丽丽";
                       r.sex = "女";
                   }
                      x = (x + 1) % 2;
            }
               
           }
       }
}

class Output implements Runnable
{
    Resource r;
    public Output(Resource r)
    {
        this.r = r;
    }
    public void run()
    {
        while(true)
        {
            synchronized (r)
            {
                System.out.println(r.name + "..." + r.sex);
            }
            
        }
    }
}

class Resource
{
   String name;
   String sex;
}

public class Person 
{
    public static void main(String[] args)
    {
        
        Resource r = new Resource();
        Input in = new Input(r);
        Output output = new Output(r);
        
        Thread t1 = new Thread(in);
        Thread t2 = new Thread(output);
        
        t1.start();
        t2.start();
    }
}

Output：

Mike...nan

丽丽...女

等待/唤醒机制。

涉及的方法：

1，wait(): 让线程处于冻结状态，被wait的线程会被存储到线程池中。

2，notify():唤醒线程池中一个线程(任意).

3，notifyAll():唤醒线程池中的所有线程。

这些方法都必须定义在同步中。

因为这些方法是用于操作线程状态的方法。

必须要明确到底操作的是哪个锁上的线程。

为什么操作线程的方法wait notify notifyAll定义在了Object类中？

因为这些方法是监视器的方法。监视器其实就是锁。

锁可以是任意的对象，任意的对象调用的方式一定定义在Object类中。

class Input implements Runnable
{
       Resource r;
       public Input(Resource r)
       {
           this.r = r;
       }
       public void run()
       {
           int x = 0;
           while(true)
           {
               synchronized (r)
               {
                   if(r.flag)
                   {
                       try {
                        r.wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                   }
                   
                   if(x == 0)
                      {
                          r.name = "Mike";
                          r.sex = "nan";
                      }
                      else
                      {
                       r.name = "丽丽";
                       r.sex = "女";
                   }
                      
                      r.flag = true;
                      r.notify();
            }
               x = (x + 1) % 2;
               
           }
       }
}

class Output implements Runnable
{
    Resource r;
    public Output(Resource r)
    {
        this.r = r;
    }
    public void run()
    {
        while(true)
        {
            synchronized (r)
            {
                if(!r.flag)
                    try {
                        r.wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                System.out.println(r.name + "..." + r.sex);
                r.flag = false;
                r.notify();
            }
        }
    }
}

class Resource
{
   String name;
   String sex;
   boolean flag = false;
}

public class Person 
{
    public static void main(String[] args)
    {
        
        Resource r = new Resource();
        Input in = new Input(r);
        Output output = new Output(r);
        
        Thread t1 = new Thread(in);
        Thread t2 = new Thread(output);
        
        t1.start();
        t2.start();
    }
}

Output：

Mike...nan

丽丽...女

Mike...nan

丽丽...女

Mike...nan

丽丽...女

Mike...nan

丽丽...女

Mike...nan

丽丽...女

Mike...nan

程序优化：

class Input implements Runnable
{
       Resource r;
       public Input(Resource r)
       {
           this.r = r;
       }
       public void run()
       {
           int x = 0;
           while(true)
           {
                   if(x == 0)
                      {
                          r.set("Mike", "nan");
                      }
                      else
                      {
                          r.set("丽丽", "女");
                   }

               x = (x + 1) % 2;
               
           }
       }
}

class Output implements Runnable
{
    Resource r;
    public Output(Resource r)
    {
        this.r = r;
    }
    public void run()
    {
        while(true)
        {
             r.out();
        }
    }
}

class Resource
{
   private String name;
   private String sex;
   private boolean flag = false;
   public synchronized void set(String name,String sex)
   {
       if(flag)
        try {
            this.wait();
        } catch (InterruptedException e) {
            // TODO 自动生成的 catch 块
            e.printStackTrace();
        }
       this.name = name;
       this.sex = sex;
       flag = true;
       this.notify();
   }
   
   public synchronized void out()
   {
       if(!flag)
           try {
                this.wait();
            } catch (InterruptedException e) {
                // TODO 自动生成的 catch 块
                e.printStackTrace();
            }
       System.out.println(name + "...+" + sex);
       flag = false;
       this.notify();
   }
   
}

public class Person 
{
    public static void main(String[] args)
    {
        
        Resource r = new Resource();
        Input in = new Input(r);
        Output output = new Output(r);
        
        Thread t1 = new Thread(in);
        Thread t2 = new Thread(output);
        
        t1.start();
        t2.start();
    }
}

Output：

Mike...nan

丽丽...女

Mike...nan

丽丽...女

Mike...nan

丽丽...女

Mike...nan

丽丽...女

Mike...nan

丽丽...女

Mike...nan