JAVA线程同步通信

以下讲解Lock线程同步通信，也是比synchronized强大的一个功能点

先看一个常规的案例：

用户类

public class Person {
    public void eat(){
        for(int i=0;i<3;i++){
            System.out.println("eat...");
        }
    }

    public void drink(){
        for(int i=0;i<3;i++){
            System.out.println("drink...");
        }
    }

    public void play(){
        for(int i=0;i<3;i++){
            System.out.println("play...");
        }
    }
}

public class LockConditionTest {
    public static void main(String[] args) {
        final Person person = new Person();
        new Thread(
                new Runnable() {
                    @Override
                    public void run() {
                        for(int i=0;i<5;i++){
                            person.eat();
                        }
                    }
                }
                )
        .start();

        new Thread(
                new Runnable() {
                    @Override
                    public void run() {
                        for(int i=0;i<5;i++){
                            person.drink();
                        }
                    }
                }
                )
        .start();

        for(int i=0;i<10;i++){
            person.play();
        }
    }
}

结果输出：

eat...
eat...
play...
play...
play...
play...
play...
play...
play...
drink...
drink...
play...
play...
play...
play...

以上案例为传统线程调用，打印的结果也是有cpu随机调度输出

现在的需求是：person 吃喝玩方法要有顺序性调用，阻止cpu随机调度输出

参考以下案例(加入Lock实现同步通信)：

public class Person {

    Lock lock = new ReentrantLock();
    Condition condition1 = lock.newCondition();
    Condition condition2 = lock.newCondition();
    Condition condition3 = lock.newCondition();
    private int shouldSub = 1;

    public void eat(){
        lock.lock();
        try{
            while(shouldSub!=1){      //是1的时候执行  不是1的时候等待
                try {
                    condition1.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            for(int i=0;i<3;i++){
                System.out.println("eat...");
            }
            shouldSub=2;
            condition2.signal();    // 1 执行完之后 通知2执行
         }finally{
             System.out.println("=======================");
             lock.unlock();
         }
    }

    public void drink(){
        lock.lock();
        try{
            while(shouldSub!=2){ //是2的时候执行  不是2的时候等待
                try {
                    condition2.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            for(int i=0;i<3;i++){
                System.out.println("drink...");
            }
            shouldSub = 3;
            condition3.signal();// 2 执行完之后 通知3执行
         }finally{
             System.out.println("=======================");
             lock.unlock();
         }
    }

    public void play(){
        lock.lock();
        try{
            while(shouldSub!=3){    //是3的时候执行  不是3的时候等待
                try {
                    condition3.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            for(int i=0;i<3;i++){
                System.out.println("play...");
            }
            shouldSub = 1;
            condition1.signal();// 3 执行完之后 通知1执行
        }finally{
            System.out.println("=======================");
             lock.unlock();
         }
    }
}

public class LockConditionTest {
    public static void main(String[] args) {
        final Person person = new Person();
        new Thread(
                new Runnable() {
                    @Override
                    public void run() {
                        for(int i=0;i<5;i++){
                            person.eat();
                        }
                    }
                }
                )
        .start();

        new Thread(
                new Runnable() {
                    @Override
                    public void run() {
                        for(int i=0;i<5;i++){
                            person.drink();
                        }
                    }
                }
                )
        .start();

        for(int i=0;i<5;i++){
            person.play();
        }
    }
}

结果输出：

eat...
eat...
eat...
=======================
drink...
drink...
drink...
=======================
play...
play...
play...
=======================
eat...
eat...
eat...
=======================
drink...
drink...
drink...
=======================
play...
play...
play...
=======================
eat...
eat...
eat...
=======================
drink...
drink...
drink...
=======================
play...
play...
play...
=======================