黑马程序员——第12天——多线程（2/2）

线程间通讯：
其实就是多个线程在操作同一个资源，
但是操作的动作不同。

class Res{String name;String sex;boolean flag = false//默认值即为假。}class Input implements Runnable{private Res r;Input(Res r){this.r = r;}public void run(){int x = 0;while(true){synchronized(r){if(r.flag)try{wait();}catch(Exception e){}if(x==0){<span style="white-space:pre"></span>r.name="mike";<span style="white-space:pre"></span>r.sex="man";}else{<span style="white-space:pre"></span>r.name="丽丽"；<span style="white-space:pre"></span>r.sex="女女女"；}x = (x+1)%2;<span style="white-space:pre"></span>r.flag = true;<span style="white-space:pre"></span>notify();}}}}class Output implements Runnable{private Res r；Output(Res r){this.r = r;}public void run(){while(true){synchronized(r){if(!r.flag)try{wait();}catch(Exception e){}System.out.println(r.name+"..."+r.sex);r.flag = false;notify();}}}}class InputOutputDemo{public static void main(String[] args) {Res r = new Res();Input in = new Input(r);Output out = new Output(r);Thread t1 = new Thread(in);Thread t2 = new Thread(out);t1.start();t2.start();}}

//notifyAll()；唤醒所有

/*
wati;
notify();
notifyAll();

都使用在同步中，因为要对持有监视器（锁）的线程操作。
所以要使用在同步中，因为只有同步才具有锁。

为什么这些操作线程的方法要定义在Object类中呢？
因为这些方法在操作同步中线程时，都必须要标他们所操作线程持有的锁
只有同一个锁上的被等待线程，可以被同一个锁上的notify唤醒。
不可以对不同锁中的线程进行唤醒。

也就是说，等待和唤醒必须是同一个锁。

而锁可以是任意对象，所以可以被任意对象调用的方法定义在Object类中。

优化一下以上程序

class Res{private String name;private String sex;private boolean flag = false//默认值即为假。public synchronized void set(String name,String sex){if (flag){try{this.wait();}catch(Exception e){}}this.name = name;this.sex = sex;flag = true;this.notify;}public void out(){if (!flag)try{this.wait();}catch(Exception e){}System.out.println(name+"...."+sex);flag = false;this.notify();}}class Input implements Runnable{private Res r;Input(Res r){this.r = r;}public void run(){int x = 0;while(true){if(x==0)r.set("mike","man");elser.set("丽丽","女女女女女");x = (x+1)%2;}}}class Output implements Runnable{private Res r；Output(Res r){this.r = r;}public void run(){while(true){r.out();}}}class InputOutputDemo2{public static void main(String[] args) {Res r = new Res();new Thread(new Input(r)).start();//匿名对象形式简化下面语句new Thread(new Output(r)).start();/*Input in = new Input(r);Output out = new Output(r);Thread t1 = new Thread(in);Thread t2 = new Thread(out);t1.start();t2.start();*/}}

生产者消费者

class ProducerConsumerDemo {public static void main(String[] args) {Resource r = new Producer();producer pro = new Producer(r);Consumer con = new Consumer(r);Thread t1 = new Thread(pro);Thread t2 = new Thread(pro);Thread t3 = new Thread(con);Thread t4 = new Thread(con);t1.start();t2.start();t3.start();t4.start();}}/*对于多个生产者和消费者。为什么要定义while判断标记。原因：让被唤醒的线程再一次判断标记。为什么定义notifyAll因为需要唤醒对方线程。因为只用notify容易出现只唤醒本方线程的情况。导致程序中的所有线程都等待。*/class Resource{private String name;private int count = 1;private boolean flag = false;public synchronized void set(String name){while(flag)try{wait()}catch(Exception e){}this.name = name+"--"+count++;System.out.println(Thread.currentThread().getName()+"...生产者..."+this.name);flag = true;this.notifyAll();}public synchronized void out(){while(!flag)try{wait();}catch(Exception e){}System.out.println(Thread.currentThread().getName()"...消费者..."+this.name);flag = false;this.notifyAll();}}class Producer implements Runnable{private Resource res;Producer(Resource res){this.res = res;}public void run(){while(true){res.set("+商品+");}}}class Cunsumer implements Runnable{private Resource res;Consumer(Resource res){this.res = res;}public void run(){while(true){res.out();}}

JDK5.0升级版

import java.util.concurrent.locks.*;class ProducerConsumerDemo2{public static void main(String[] args) {Resource r = new Producer();producer pro = new Producer(r);Consumer con = new Consumer(r);Thread t1 = new Thread(pro);Thread t2 = new Thread(pro);Thread t3 = new Thread(con);Thread t4 = new Thread(con);t1.start();t2.start();t3.start();t4.start();}}/*<strong>JDK1.5中提供了多线程升级解决方案。（显示的锁机制以及显示的锁对象上的等待唤醒操作机制。一个锁可以有多组condition对象。）将同步Synchronized替换成现实Lock操作。将Object中的wait,notify,notifyAll，替换了Condition对象。该对象可以Lock锁 进行获取。该示例中，实现了本方只唤醒对方操作。</strong>*/class Resource{private String name;private int count = 1;private boolean flag = false;private Lock lock = new ReentrantLock();private Condition condition_pro = lock.newCondition();private Condition condition_con = lock.newCondition();public void set(String name)throws InterruptedException{lock.lock();try{while(flag)condition_pro.await();//t1,t2this.name = name+"--"+count++;System.out.println(Thread.currentThread().getName()+"...生产者..."+this.name);flag = true;condition_con.signal();}finally{lock.unlock();//释放锁的动作一定要执行。}}//  t3  t4public void out()throws InterruptedException{lock.lock();try{while(!flag)condition_con.await();System.out.println(Thread.currentThread().getName()"...消费者..."+this.name);flag = false;condition_pro.signal();}}}class Producer implements Runnable{private Resource res;Producer(Resource res){this.res = res;}public void run(){while(true){res.set("+商品+");}}}class Cunsumer implements Runnable{private Resource res;Consumer(Resource res){this.res = res;}public void run(){while(true){res.out();}}

stop方法已经过时。

如何停止线程？
只有一种，run方法结束。
开启多线程运行，运行代码通常是循环结构。

只要控制住循环，就可以让run方法结束，也就是线程结束。

特殊情况：
当线程出于冻结状态。
就不会读取到标记。那么线程就不会结束。

当没有指定的方式让冻结的线程恢复到运行状态时，这时需要对冻结状态进行清除。
强制让线程恢复到运行状态中来，这样就可以操作标记让线程结束。

Thread类提供了该方法：Interrupt()；(sleep,wait,join都能唤醒)

class StopThread implements Runnable{private boolean flag = true;public synchronized void run(){while(flag){try{wait();}catch (InterruptedException e){System.out.println(Thread.currentThread().getName()+"...Exception");}System.out.println(Thread.currentThread().getName()+"...run");}}public void changeFleg(){flag = false;}}class StopThreadDemo{public static void main(String[] args) {StopThread st = new StopThread();Thread t1 = new Thread(st);Thread t2 = new Thread(st);t1.setDaemon(true);//<strong>守护线程</strong>t2.setDaemon(true);t1.start();t2.start();int num = 0;while(true){if(num++ ==60);{//st.changeFlag();<span style="white-space:pre"></span>//t1.interrupt();<span style="white-space:pre"></span>//t2.interrupt();<span style="white-space:pre"></span>break;}System.out.println(Thread.currentThread().getName()+"....."+num);}System.out.println("over");}}

join:
当A线程执行到了B线程的.join()方法时，A就会等待。等B线程执行完，A才会执行。

join可以用来临时加入线程执行。

class Demo implements Runnable{public void run(){for(int x = 0; x<70; x++){System.out.println(Thread.currentThread().getName()+"..."+x);}}}class JoinDemo {public static void main(String[] args) throws Exception {Demo d = new Demo();Thread t1 = new Thread(d);Thread t2 = new Thread(d);t1.start();t1.join();//t1抢夺CPU执行权t2.start();for (int x = 0; x<80 ; x++ ){System.out.println("main....."+x);}System.out.println("over");}}

线程的优先级，时停止yield()

class Demo implements Runnable{public void run(){for(int x = 0; x<70; x++){System.out.println(Thread.currentThread().getName()+"..."+x);Thread.yield();//稍微减缓线程运行，暂时停止。}}}class JoinDemo {public static void main(String[] args) throws Exception {Demo d = new Demo();Thread t1 = new Thread(d);Thread t2 = new Thread(d);t1.start();t1.setPriority(Thread.MAX_PRIORITY);//设置优先级，默认值为5，范围1-10。MAX，MIN,NORM//t1.join();t2.start();for (int x = 0; x<80 ; x++ ){System.out.println("main....."+x);}System.out.println("over");}}

技巧写法，用匿名内部类

class ThreadTest {public static void main(String[] args) {new Thread(){public void run(){for(int x=0; x<100; x++){System.out.println(Thread.currentThread().getName()+"....."+x);}}}.start();for(int x=0; x<100; x++){System.out.println(Thread.currentThread().getName()+"...."+x);}Runnable r = new Runnable(){public void run(){for(int x=0; x<100; x++){System.out.println(Thread.currentThread().getName()+"...."+x);}}};new Thread(r).start();//new Test1().start();}}/*class Test1 extends Thread{public void run(){for(int x=0; x<100;x++){System.out.println(Thread.currentThread().getName()+"...."+x);}}}*/