1.5之前的写法.

/*生产者消费者两个线程生产,两个线程消费.而且要是生产一个消费一个.主要问题:使用notifyAll会唤醒本方线程,这个问题要lock和conditions来处理.如果不用notifyAll,只用notify所有线程都会wait.*/class  TestMain{    public static void main(String[] args)     {        Resource res = new Resource();        Producer pro = new Producer(res);        Consumer con = new Consumer(res);        Thread t1 = new Thread(res);        Thread t2 = new Thread(pro);        Thread t3 = new Thread(res);        Thread t4 = new Thread(pro);        t1.start();        t2.start();        t3.start();        t4.start();    }}class Resource{    private String name;    private int count=1;    private boolean flag =false;    public synchronized void set(String name){        if(flag){            try{                wait();//线程会停在这里,但是当线程被唤醒的时候,一样要循环判断标记.所以if要改成while            }catch(Exception e){                //如果出异常,方法结束,就出了synchronized代码块锁也有释放了.这点不像lock.nulock().nulock是一定要执行的,出了异常,方法结束也是要执行的.            }        }                    this.name=name+"--"+count++;        System.out.println(Thread.curentThread().getName()+"生产的"+this.name);        flag=true;        this.notify();//这里唤醒的时候可能唤醒的是本方线程,导致所有线程wait,所以要用 notifyAll()    }    public synchronized void out(){        if(!flag){            try{                wait();            }catch(Exception e){                //            }        }        System.out.println(Thread.curentThread().getName()+"消费者"+this.name);        flag=false;        this.notify();    }}class Producer implements Runnable{    private Resource res;    Producer(Resource res){        this.res=res;    }    @Override    public void run(){        while(true){            res.set("+商品+");        }    }}class Consumer implements Runnable{    private Resource res;    Producer(Resource res){        this.res=res;    }    @Override    public void run(){        while(true){            res.out();        }    }}

1.5之后的写法

/*生产与消费者jdk1.5 之后的Lock与Condition可以保证唤醒的是对方线程,可以唤醒对方一个,也可以是所有.主要看用的是signal与signalAll()*/class  TestMain{    public static void main(String[] args)     {        //要操作的数据,资源        Resource res = new Resource();        //两个生产,消费线程        Producer pro = new Producer(res);        Resource res = new Resource();        Producer pro = new Producer(res);        Consumer con = new Consumer(res);        Thread t1 = new Thread(res);        Thread t2 = new Thread(pro);        Thread t3 = new Thread(res);        Thread t4 = new Thread(pro);        t1.start();        t2.start();        t3.start();        t4.start();    }}/*  资源类,里面的要操作的数据,操作数据的方法,标记,锁,Condition.*/class Resource{    private String name;    private int count=1;    private boolean flag =false;        //1.5之后lock代替了,syschronized    private Lock lock =new ReentrantLock();    //Condition 代替了Objcet里面的wait,notify,notifyAll    private Condition condition1=lock.newCondition();        //用来分组线程,本方只唤醒对方线程的操作.    private Condition condition2=lock.newCodition();    //去掉了synchronized关键字    public void set(String name){        while(flag){            try{                condition1.await();            }catch(Exception e){                //这里一但出异常,因为还没有执行lock.unlock()会,所以方法结束但是锁还没有释放,所以一定要入finally里面去执行nulock();            }        }                    this.name=name+"--"+count++;        System.out.println(Thread.curentThread().getName()+"生产的"+this.name);        flag=true;        //condition.signalAll();//这样可能会唤醒本方线程.用signal()会全部等待.        condition2.signal()//这样可以保证唤醒的是对方线程.        lock.unlock();    }    //去掉synchronized    public  void out(){        lock.loct();        try{            while(!flag){                condition2.await()//线程被唤醒后,一定要循环判断标记            }            System.out.println(Thread.curentThread().getName()+"消费者"+this.name);            flag=false;            //condition.signalAll();//这里同样可能会唤醒本方的线程,要改的            condition2.signa();        }catch(InterrputedException e){            //await()的时候可会出异常,出了异常方法结束了,但也定要nulock()        }finally{            lock.nulock();        }    }}/*生产者线程*/class Producer implements Runnable{    private Resource res;    Producer(Resource res){        this.res=res;    }    @Override    public void run(){        while(true){            res.set("+商品+");        }    }}/*消费者线程*/class Consumer implements Runnable{    private Resource res;    Producer(Resource res){        this.res=res;    }    @Override    public void run(){        while(true){            res.out();        }    }}