信号量在多线程通讯运用

信号量在多线程通讯运用

同步的三个方法:

必须在同步块 或者同步方法中使用

notify()  停止访问当前线程,转去执行挂起的线程notifyALL()wait() 挂起 释放对线程资源的访问  如果有参数时间 那么再等待特定的时间再挂起

class CommonTalkVar{ private char product; /**同步信号量 * true: 持有产品状态 * false: 已经消费产品状态 * */ private boolean isProduced=false; /** * @description production method */ public synchronized void putCommonData(char product){ if(isProduced){ try { System.out.println(Thread.currentThread().getName()+"消费者还没有消费产品"); wait(); }catch (InterruptedException e){ e.printStackTrace(); } } this.product=product; this.isProduced=true; System.out.println(Thread.currentThread().getName()+"生产者生产:"+this.product); notify(); } /** * @description consumer method */ public synchronized char getCommonData(){ if(!isProduced){ try { System.out.println(Thread.currentThread().getName()+"生产者还没有生产产品"); wait(); }catch (InterruptedException e){ e.printStackTrace(); } } this.isProduced=false; System.out.println(Thread.currentThread().getName()+"消费者消费:"+this.product); notify(); return this.product; }}class Consumer extends Thread{ private CommonTalkVar commonTalkVar; public Consumer(CommonTalkVar commonTalkVar){ this.commonTalkVar=commonTalkVar; } @Override public void run() { char tempc; do{ try { Thread.sleep((int)(Math.random()*3000)); }catch (InterruptedException e){ e.printStackTrace(); } tempc=commonTalkVar.getCommonData(); }while (tempc!='D'); }}class Product extends Thread{ private CommonTalkVar commonTalkVar; public Product(CommonTalkVar commonTalkVar){ this.commonTalkVar=commonTalkVar; } @Override public void run() { for (char i = 'A'; i <= 'D'; i++){ try { Thread.sleep((int)(Math.random()*3000)); }catch (InterruptedException e){ e.printStackTrace(); } commonTalkVar.putCommonData(i); } }}public class ConsumerAndProduct { public static void main(String[] args) { CommonTalkVar talkVar = new CommonTalkVar(); new Consumer(talkVar).start(); new Product(talkVar).start(); }}

多线程的的顺序控制

实际上就是注意 notifyALL() 方法的控制用法

package Thread;public class Demo1_Synchronized { /** * @param args * 同步代码块 */ public static void main(String[] args) { final Printer p = new Printer(); 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 Printer { Demo d = new Demo(); private static volatile int signal=1; public void print1() throws InterruptedException { synchronized (this) { while(this.signal!=1) { this.wait(); } this.signal=2; System.out.println("11111"); this.notifyAll(); } } public void print2() throws InterruptedException { synchronized (this) { while(this.signal!=2) { this.wait(); } this.signal=3; System.out.println("22222"); this.notifyAll(); } } public void print3() throws InterruptedException { synchronized (this) { while(this.signal!=3) { this.wait(); } this.signal=1; System.out.println("33333"); this.notifyAll(); } }}//定义的锁类class Demo {}

锁的同步

package Thread;import java.util.concurrent.locks.ReentrantLock;public class Test6 { public static void main(String[] args) { new Ticket12().start(); new Ticket12().start(); new Ticket12().start(); new Ticket12().start(); }}class Ticket12 extends Thread { private static volatile int ticket = 100; private static final ReentrantLock lock=new ReentrantLock(); public void run() { while (true) { lock.lock(); try { if (ticket <= 0) { break; } try { Thread.sleep(10); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println(getName() + "这是第" + ticket-- + "号票"); } finally { lock.unlock(); } } }}

可重入锁的用法

package Thread;import java.util.concurrent.locks.Condition;import java.util.concurrent.locks.ReentrantLock;public class Demo1_ReentrantLock { public static void main(String[] args) { final PrinterReentrantLock p = new PrinterReentrantLock(); 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 PrinterReentrantLock { private int signal=1; private static final ReentrantLock lock=new ReentrantLock(); private static final Condition c1=lock.newCondition(); private static final Condition c2=lock.newCondition(); private static final Condition c3=lock.newCondition(); public void print1() throws InterruptedException { lock.lock(); try { while (this.signal != 1) { c1.await(); } this.signal = 2; System.out.println("11111"); c2.signal(); } finally { lock.unlock(); } } public void print2() throws InterruptedException { lock.lock(); try { while (this.signal != 2) { c2.await(); } this.signal = 3; System.out.println("22222"); c3.signal(); } finally { lock.unlock(); } } public void print3() throws InterruptedException { lock.lock(); try { while (this.signal != 3) { c3.await(); } this.signal = 1; System.out.println("33333"); c1.signal(); } finally { lock.unlock(); } }}

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