java基礎-多線程互斥鎖

多線程(JDK1.5的新特性互斥鎖)
* 1.同步
 * 使用ReentrantLock類的lock()和unlock()方法進行同步
* 2.通信
 * 使用ReentrantLock類的newCondition()方法可以獲取Condition對象
 * 需要等待的時候使用Condition的await()方法, 喚醒的時候用signal()方法
 * 不同的線程使用不同的Condition, 這樣就能區分喚醒的時候找哪個線程了

 

 

import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;

public class Demo3_ReentrantLock {

 /**
  * @param args
  */
 public static void main(String[] args) {
  final Printer3 p = new Printer3();
  
  new Thread() {
   public void run() {
    while(true) {
     try {
      p.print1();
     } catch (InterruptedException e) {
      
      e.printStackTrace();
     }
    }
   }
  }.start();
  
  new Thread() {
   public void run() {
    while(true) {
     try {
      p.print2();
     } catch (InterruptedException e) {
      
      e.printStackTrace();
     }
    }
   }
  }.start();
  
  new Thread() {
   public void run() {
    while(true) {
     try {
      p.print3();
     } catch (InterruptedException e) {
      
      e.printStackTrace();
     }
    }
   }
  }.start();
 }

}

class Printer3 {
 private ReentrantLock r = new ReentrantLock();
 private Condition c1 = r.newCondition();
 private Condition c2 = r.newCondition();
 private Condition c3 = r.newCondition();
 
 private int flag = 1;
 public void print1() throws InterruptedException {       
  r.lock();        //獲取鎖
   if(flag != 1) {
    c1.await();
   }
   System.out.print("黑");
   System.out.print("馬");
   System.out.print("程");
   System.out.print("序");
   System.out.print("員");
   System.out.print("\r\n");
   flag = 2;
   //this.notify();      //隨機喚醒單個等待的線程
   c2.signal();
  r.unlock();        //釋放鎖
 }
 
 public void print2() throws InterruptedException {
  r.lock();
   if(flag != 2) {
    c2.await();
   }
   System.out.print("傳");
   System.out.print("智");
   System.out.print("播");
   System.out.print("客");
   System.out.print("\r\n");
   flag = 3;
   //this.notify();
   c3.signal();
  r.unlock();
 }
 
 public void print3() throws InterruptedException {
  r.lock();
   if(flag != 3) {
    c3.await();
   }
   System.out.print("i");
   System.out.print("t");
   System.out.print("h");
   System.out.print("e");
   System.out.print("i");
   System.out.print("m");
   System.out.print("a");
   System.out.print("\r\n");
   flag = 1;
   c1.signal();
  r.unlock();
 }
}