Java 多线程之间实现通讯

多线程之间如何实现通讯

代码实现基本实现共享资源源实体类

<code>class Res {
\tpublic String userSex;
\tpublic String userName;
}
/<code>

输入线程资源

<code>class IntThrad extends Thread {
\tprivate Res res;

\tpublic IntThrad(Res res) {
\t\tthis.res = res;
\t}

\t@Override
\tpublic void run() {
\t\tint count = 0;
\t\twhile (true) {
\t\t\t\tif (count == 0) {
\t\t\t\t\tres.userName = "余胜军";
\t\t\t\t\tres.userSex = "男";
\t\t\t\t} else {
\t\t\t\t\tres.userName = "小紅";
\t\t\t\t\tres.userSex = "女";
\t\t\t\t}
\t\t\t\tcount = (count + 1) % 2;
\t\t\t}
\t}
}

/<code>

输出线程

<code>class OutThread extends Thread {
\tprivate Res res;

\tpublic OutThread(Res res) { 

\t\tthis.res = res;
\t}

\t@Override
\tpublic void run() {
\t\twhile (true) {
\t\t\t\tSystem.out.println(res.userName + "--" + res.userSex);
\t\t}
\t}
}
/<code>

运行代码

<code>Res res = new Res();
IntThrad intThrad = new IntThrad(res);
OutThread outThread = new OutThread(res);
intThrad.start();
outThread.start();
/<code>

运行代码

注意：数据发生错乱，造成线程安全问题解决线程安全问题IntThrad 加上synchronized

<code>class IntThrad extends Thread {
\tprivate Res res;

\tpublic IntThrad(Res res) {
\t\tthis.res = res;
\t}

\t@Override
\tpublic void run() {
\t\tint count = 0;
\t\twhile (true) {
\t\t\tsynchronized (res) {
\t\t\t\tif (count == 0) {
\t\t\t\t\tres.userName = "余胜军";
\t\t\t\t\tres.userSex = "男";
\t\t\t\t} else {
\t\t\t\t\tres.userName = "小紅";
\t\t\t\t\tres.userSex = "女";
\t\t\t\t}
\t\t\t\tcount = (count + 1) % 2;
\t\t\t}

\t\t}
\t}
}
/<code>

输出线程加上synchronized

<code>class Res {
\tpublic String userName;
\tpublic String sex;
}

class InputThread extends Thread {
\tprivate Res res;

\tpublic InputThread(Res res) {
\t\tthis.res = res;
\t} 


\t@Override
\tpublic void run() {
\t\tint count = 0;
\t\twhile (true) {
\t\t\t synchronized (res) {
\t\t\tif (count == 0) {
\t\t\t\tres.userName = "余胜军";
\t\t\t\tres.sex = "男";
\t\t\t} else {
\t\t\t\tres.userName = "小红";
\t\t\t\tres.sex = "女";
\t\t\t}
\t\t\tcount = (count + 1) % 2;
\t\t}

\t\t}
\t}
}

class OutThrad extends Thread {
\tprivate Res res;

\tpublic OutThrad(Res res) {
\t\tthis.res = res;
\t}

\t@Override
\tpublic void run() {
\t\twhile (true) {
\t\t\tsynchronized (res) {
\t\t\t\tSystem.out.println(res.userName + "," + res.sex);
\t\t\t}
\t\t}

\t}
}

public class ThreadDemo01 {

\tpublic static void main(String[] args) {
\t\tRes res = new Res();
\t\tInputThread inputThread = new InputThread(res);
\t\tOutThrad outThrad = new OutThrad(res);
\t\tinputThread.start();
\t\toutThrad.start();
\t}

}
 

/<code>

wait、notify方法

1.因为涉及到对象锁,他们必须都放在synchronized中来使用. Wait、Notify一定要在synchronized里面进行使用。2.Wait必须暂定当前正在执行的线程,并释放资源锁,让其他线程可以有机会运行3. notify/notifyall: 唤醒因锁池中的线程,使之运行

注意:一定要在线程同步中使用,并且是同一个锁的资源

<code>class Res {
\tpublic String userSex;
\tpublic String userName;
\t//线程通讯标识
\tpublic boolean flag = false;
}

/<code>

<code>class IntThrad extends Thread {
\tprivate Res res;

\tpublic IntThrad(Res res) {
\t\tthis.res = res;\t\t
\t}

\t@Override
\tpublic void run() {
\t\tint count = 0;
\t\twhile (true) {
\t\t\tsynchronized (res) {
\t\t\t\tif (res.flag) {
\t\t\t\t\ttry {
\t\t\t\t\t   // 当前线程变为等待，但是可以释放锁
\t\t\t\t\t\tres.wait();
\t\t\t\t\t} catch (Exception e) { 


\t\t\t\t\t}
\t\t\t\t}
\t\t\t\tif (count == 0) {
\t\t\t\t\tres.userName = "余胜军";
\t\t\t\t\tres.userSex = "男";
\t\t\t\t} else {
\t\t\t\t\tres.userName = "小紅";
\t\t\t\t\tres.userSex = "女";
\t\t\t\t}
\t\t\t\tcount = (count + 1) % 2;
\t\t\t\tres.flag = true;
\t\t\t\t// 唤醒当前线程
\t\t\t\tres.notify();
\t\t\t}

\t\t}
\t}
}
/<code>

<code>class OutThread extends Thread {
\tprivate Res res;

\tpublic OutThread(Res res) {
\t\tthis.res = res;
\t}

\t@Override
\tpublic void run() {
\t\twhile (true) {
\t\t\tsynchronized (res) {
\t\t\t\tif (!res.flag) {
\t\t\t\t\ttry {
\t\t\t\t\t\tres.wait();
\t\t\t\t\t} catch (Exception e) {
\t\t\t\t\t\t// TODO: handle exception
\t\t\t\t\t}
\t\t\t\t}
\t\t\t\tSystem.out.println(res.userName + "--" + res.userSex);
\t\t\t\tres.flag = false;
\t\t\t\tres.notify();
\t\t\t}
\t\t}
\t}
}
/<code>

<code>public class ThreaCommun { 

\tpublic static void main(String[] args) {
\t\tRes res = new Res();
\t\tIntThrad intThrad = new IntThrad(res);
\t\tOutThread outThread = new OutThread(res);
\t\tintThrad.start();
\t\toutThread.start();
\t}
}
/<code>

wait与sleep区别

对于sleep()方法，我们首先要知道该方法是属于Thread类中的。而wait()方法，则是属于Object类中的。sleep()方法导致了程序暂停执行指定的时间，让出cpu该其他线程，但是他的监控状态依然保持者，当指定的时间到了又会自动恢复运行状态。在调用sleep()方法的过程中，线程不会释放对象锁。而当调用wait()方法的时候，线程会放弃对象锁，进入等待此对象的等待锁定池，只有针对此对象调用notify()方法后本线程才进入对象锁定池准备获取对象锁进入运行状态。

Lock锁

在 jdk1.5 之后，并发包中新增了 Lock 接口(以及相关实现类)用来实现锁功能，Lock 接口提供了与 synchronized 关键字类似的同步功能，但需要在使用时手动获取锁和释放锁。Lock写法

<code>Lock lock  = new ReentrantLock();
lock.lock();
try{
//可能会出现线程安全的操作 

}finally{
//一定在finally中释放锁
//也不能把获取锁在try中进行，因为有可能在获取锁的时候抛出异常
  lock.ublock();
}

/<code>

Lock与synchronized 关键字的区别Lock 接口可以尝试非阻塞地获取锁 当前线程尝试获取锁。如果这一时刻锁没有被其他线程获取到，则成功获取并持有锁。Lock 接口能被中断地获取锁 与 synchronized 不同，获取到锁的线程能够响应中断，当获取到的锁的线程被中断时，中断异常将会被抛出，同时锁会被释放。Lock 接口在指定的截止时间之前获取锁，如果截止时间到了依旧无法获取锁，则返回。Condition用法Condition的功能类似于在传统的线程技术中的,Object.wait()和Object.notify()的功能。代码

<code>Condition condition = lock.newCondition();
res. condition.await();  类似wait
res. Condition. Signal() 类似notify
/<code>

<code>class Res {
\tpublic String userName;
\tpublic String sex;
\tpublic boolean flag = false;
\tLock lock = new ReentrantLock();
}

class InputThread extends Thread { 

\tprivate Res res;
\tCondition newCondition;
\tpublic InputThread(Res res,\tCondition newCondition) {
\t\tthis.res = res;
\t\tthis.newCondition=newCondition;
\t}

\t@Override
\tpublic void run() {
\t\tint count = 0;
\t\twhile (true) {
\t\t\t// synchronized (res) {

\t\t\ttry {
\t\t\t\tres.lock.lock();
\t\t\t\tif (res.flag) {
\t\t\t\t\ttry {
//\t\t\t\t\t\tres.wait();
\t\t\t\t\t\tnewCondition.await();
\t\t\t\t\t} catch (Exception e) {
\t\t\t\t\t\t// TODO: handle exception
\t\t\t\t\t}
\t\t\t\t}
\t\t\t\tif (count == 0) {
\t\t\t\t\tres.userName = "余胜军";
\t\t\t\t\tres.sex = "男";
\t\t\t\t} else {
\t\t\t\t\tres.userName = "小红";
\t\t\t\t\tres.sex = "女";
\t\t\t\t}
\t\t\t\tcount = (count + 1) % 2;
\t\t\t\tres.flag = true;
//\t\t\t\tres.notify();
\t\t\t\tnewCondition.signal();
\t\t\t} catch (Exception e) {
\t\t\t\t// TODO: handle exception
\t\t\t}finally {
\t\t\t\tres.lock.unlock();
\t\t\t}
\t\t}

\t\t// }
\t}
}

class OutThrad extends Thread {
\tprivate Res res;
\tprivate Condition newCondition;
\tpublic OutThrad(Res res,Condition newCondition) {
\t\tthis.res = res; 

\t\tthis.newCondition=newCondition;
\t}

\t@Override
\tpublic void run() {
\t\twhile (true) {
//\t\t\tsynchronized (res) {
\t\t\ttry {
\t\t\t\tres.lock.lock();
\t\t\t\tif (!res.flag) {
\t\t\t\t\ttry {
//\t\t\t\t\t\tres.wait();
\t\t\t\t\t\tnewCondition.await();
\t\t\t\t\t} catch (Exception e) {
\t\t\t\t\t\t// TODO: handle exception
\t\t\t\t\t}
\t\t\t\t}
\t\t\t\tSystem.out.println(res.userName + "," + res.sex);
\t\t\t\tres.flag = false;
//\t\t\t\tres.notify();
\t\t\t\tnewCondition.signal();
\t\t\t} catch (Exception e) {
\t\t\t\t// TODO: handle exception
\t\t\t}finally {
\t\t\t\tres.lock.unlock();
\t\t\t}
//\t\t\t}
\t\t}

\t}
}

public class ThreadDemo01 {

\tpublic static void main(String[] args) {
\t\tRes res = new Res();
\t\tCondition newCondition = res.lock.newCondition();
\t\tInputThread inputThread = new InputThread(res,newCondition);
\t\tOutThrad outThrad = new OutThrad(res,newCondition);
\t\tinputThread.start();
\t\toutThrad.start();
\t}

}
/<code>

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