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@liruiyi962464 2017-03-22T03:42:31.000000Z 字数 6849 阅读 437

线程

java

  • 进程里边有多个线程
  • CPU在同一个时间点上只有一个线程在工作
  • CPU只管理资源，线程的进入是随机的
  • 共享
  • 并发
  • 随机

继承Therad类创建多线程

  • 普通java类继承自Therad类，就成为一个线程类，并且可以通过该类的start()方法来启动线程
  • Therad类的子类可以直接实例化，但是要从写run()方法
  1. public class Test1_Therad {
  2.     public static void main(String[] args) {
  3.         MyThread mt = new MyThread();
  4.         mt.start();
  6.         for(int i = 0;i<5;i++){
  7.             System.out.println("主方法。");
  8.         }
  9.         //匿名内部类相当于父类的子类
  10.         new Thread(){
  11.             public void run(){
  12.                 for(int i = 0;i<5;i++){
  13.                     try {
  14.                         sleep(1000);
  15.                     } catch (InterruptedException e) {
  16.                         // TODO Auto-generated catch block
  17.                         e.printStackTrace();
  18.                     }
  19.                     System.out.println("匿名内部类");
  20.                 }
  21.             }
  22.         }.start();
  23.         //new.MyThread().start();
  24.     }
  25. }
  26. class MyThread extends Thread{
  27.     @Override
  28.     public void run() {
  29.         // TODO Auto-generated method stub
  30.         for(int i = 0;i<5;i++){
  31.             try {
  32.                 sleep(1000);
  33.             } catch (InterruptedException e) {
  34.                 // TODO Auto-generated catch block
  35.                 e.printStackTrace();
  36.             }
  37.             System.out.println("先定一个小目标123456789");
  38.         }
  39.         super.run();
  40.     }
  41. }
  1. public class Task3_3Thread {
  2.     public static void main(String[] args) {
  3.         TrainThread tt1 = new TrainThread();
  4.         tt1.setName("火车1");
  5.         tt1.start();
  6.     }
  7. }
  8. class TrainThread extends Thread{
  9.     @Override
  10.     public synchronized void run() {
  11.         // TODO Auto-generated method stub
  12.         synchronized (TrainThread.class) {
  13.             System.out.println(Thread.currentThread().getName()+"通过山洞");
  14.             try {
  15.                 Thread.sleep(2000);
  16.             } catch (InterruptedException e) {
  17.                 // TODO Auto-generated catch block
  18.                 e.printStackTrace();
  19.             }
  20.         }
  21.     }
  22. }

实现接口Runnable创建多线程

  • 实现Runnable接口必须借助Thread类才能创建线程
    1.创建Runnable接口的类的实例
    2.创建一个Thread对象，将第一步实例化得到的Runnable对象作为参数传入Thread类的构造犯法
  • 通过Thread类的start()方法启动线程
  1. public class Test2_Runnable {
  2.     public static void main(String[] args) {
  3.         MyRunnable mr = new MyRunnable();
  4.         Thread t =  new Thread(mr);
  5.         t.start();
  6.     }
  7. }
  8. class MyRunnable implements Runnable{
  10.     @Override                   
  11.     public void run() {
  12.         // TODO Auto-generated method stub
  13.         for(int i = 0;i<5;i++){
  14.             try {
  15.                 Thread.sleep(1000);
  16.             } catch (InterruptedException e) {
  17.                 // TODO Auto-generated catch block
  18.                 e.printStackTrace();
  19.             }
  20.             System.out.println("Runnable");
  21.         }
  22.     }
  24. }
  1. public class Task3_3 {
  2.     public static void main(String[] args) {
  3.         TrainThread tt = new TrainThread();
  4.         Thread t1 = new Thread(tt, "火车1");
  5.         t1.start();
  6.     }
  7. }
  8. class TrainThread implements Runnable{
  10.     @Override
  11.     public synchronized void run() {
  12.         // TODO Auto-generated method stub
  13.         System.out.println(Thread.currentThread().getName()+"通过山洞");
  14.         try {
  15.             Thread.sleep(2000);
  16.         } catch (InterruptedException e) {
  17.             // TODO Auto-generated catch block
  18.             e.printStackTrace();
  19.         }
  20.     }
  22. }

线程常用方法

  1. public class Test3_ThreadFiled {
  2.     public static void main(String[] args) {
  3.         new Thread("线程a"){
  4.             public void run() {
  5.                 System.out.println(getName()+"........1..aaa...."+getId());
  6.             }
  7.         }.start();
  8.         new Thread("线程b"){
  9.             public void run() {
  10.                 System.out.println(getName()+".........2...bbb.."+getId());
  11.             }
  12.         }.start();
  13.         new Thread(new Runnable() {     
  14.             @Override
  15.             public void run() {
  16.                 // TODO Auto-generated method stub
  17.                 System.out.println("没有设置/获取名字Runnable......3........."+Thread.currentThread().getId());
  18.                 //currentThread()返回当前线程的引用
  19.                 //Thread.currentThread().setName("线程c");设置线程的名字
  20.                 System.out.println(Thread.currentThread().getName()+"：设置/获取名字........4...Runnable......"+Thread.currentThread().getId());
  21.             }
  22.         },"线程c").start();//在这里也可以线程名字
  23.         Thread.currentThread().setName("我是主线程");
  24.         System.out.println(Thread.currentThread().getName()+"...........5............"+Thread.currentThread().getId());
  25.     }
  26. }

线程同步

  • 直接在方法中添加关键字也可以加锁synchronized
  • synchronized运行完之后再换/加锁
  1. package com.xianchengtongbu;
  3. public class Test_Synchronized {
  4.     public static void main(String[] args) {
  5.         Printer p = new Printer();
  6.         new Thread(){
  7.             public void run() {
  8.                 while(true){
  9.                     p.print1();
  10.                 }};
  11.         }.start();
  12.         new Thread(){
  13.             public void run() {
  14.                 while(true){
  15.                     p.print2();
  16.                 }
  17.             };}.start();
  18.     }
  19. }
  20. class Printer{
  21.     Object obg = new Object();
  22.     //直接在方法中添加关键字也可以加锁synchronized
  23.     public void print1() {//线程同步
  24.     //如果同步非静态方法，锁对象是this
  25.     //如果同步静态方法，锁对象是.class
  26.         synchronized (obg) {//synchronized运行完之后再换/加锁
  27.             System.out.print("每");
  28.             System.out.print("天");
  29.             System.out.print("进");
  30.             System.out.print("步");
  31.             System.out.print("一");
  32.             System.out.print("点");
  33.             System.out.print("点");
  34.             System.out.println();
  35.         }   
  36.     }//锁对象是this
  37.     public void print2() {//线程不同步
  38.             System.out.print("好");
  39.             System.out.print("好");
  40.             System.out.print("学");
  41.             System.out.print("习");
  42.             System.out.println();
  43.     }
  44. }

死锁

  • 产生的原因：俩个线程都需要同一个对象，这个互相等待对方释放锁的过程，会导致死锁
  1. public class Test1_SiSuo {
  2.     // 创建俩个筷子
  3.     private static String s1 = "筷子左";
  4.     private static String s2 = "筷子右";
  6.     public static void main(String[] args) {
  7.         // 匿名内部类相当于父类的子类
  8.         new Thread("皮皮虾") {
  9.             @Override
  10.             public void run() {
  11.                 // TODO Auto-generated method stub
  12.                 while (true) {
  13.                     synchronized (s1) {
  14.                         System.out.println(this.getName()+"获得"+s1+"等待"+s2);
  15.                         synchronized (s2) {
  16.                             System.out.println(this.getName()+"获得"+s2);
  17.                         }
  18.                     }
  19.                 }
  20.             }
  21.         }.start();
  22.         new Thread("PPD") {
  23.             @Override
  24.             public void run() {
  25.                 // TODO Auto-generated method stub
  26.                 while (true) {
  27.                     synchronized (s2) {
  28.                         System.out.println(this.getName()+"获得"+s2+"等待"+s1);
  29.                         synchronized (s1) {
  30.                             System.out.println(this.getName()+"获得"+s1);
  31.                         }
  32.                     }
  33.                 }
  34.             }
  35.         }.start();
  36.     }
  37. }

线程同步

  • wait()： 在其他线程调用此对象的 notify() 方法或 notifyAll() 方法前，导致当前线程等待。
  • notify()：唤醒在此对象监视器上等待的单个线程。
  • notifyAll()： 唤醒在此对象监视器上等待的所有线程。

俩个通信

  1. public class Test1_Tongxin {
  2.     public static void main(String[] args) {
  3.         Printer p = new Printer();
  4.         new Thread(){
  5.             @Override
  6.             public void run() {
  7.                 // TODO Auto-generated method stub
  8.                 while(true){
  9.                     try {
  10.                         sleep(1000);
  11.                         p.print1();
  12.                     } catch (Exception e) {
  13.                         // TODO Auto-generated catch block
  14.                         e.printStackTrace();
  15.                     }
  16.                 }
  17.             }
  18.         }.start();
  19.         new Thread(){
  20.             @Override
  21.             public void run() {
  22.                 // TODO Auto-generated method stub
  23.                 while(true){
  24.                     try {
  25.                         sleep(1000);
  26.                         p.print2();
  27.                     } catch (Exception e) {
  28.                         // TODO Auto-generated catch block
  29.                         e.printStackTrace();
  30.                     }
  31.                 }
  32.             }
  33.         }.start();
  34.     }
  35. }
  36. class Printer{
  37.     private int n = 1;
  38.     public void print1() throws Exception{
  39.         synchronized (this) {
  40.             if(n!=1){
  41.                 this.wait();//等待
  42.             }
  43.             System.out.print("每");
  44.             System.out.print("天");
  45.             System.out.print("进");
  46.             System.out.print("步");
  47.             System.out.print("一");
  48.             System.out.print("点");
  49.             System.out.print("点");
  50.             System.out.println();
  51.             n = 2;
  52.             this.notify();//唤醒
  53.         }
  54.     }
  55.     public void print2() throws Exception{
  56.         synchronized (this) {
  57.             if(n!=2){
  58.                 this.wait();
  59.             }
  60.             System.out.print("好");
  61.             System.out.print("好");
  62.             System.out.print("学");
  63.             System.out.print("习");
  64.             System.out.println();
  65.             n = 1;
  66.             this.notify();
  67.         }
  68.     }
  69. }

多个通信

  1. public class Test1_Tongxin {
  2.     public static void main(String[] args) {
  3.         Printer p = new Printer();
  4.         new Thread(){
  5.             @Override
  6.             public void run() {
  7.                 // TODO Auto-generated method stub
  8.                 while(true){
  9.                     try {
  10.                         sleep(1000);
  11.                         p.print1();
  12.                     } catch (Exception e) {
  13.                         // TODO Auto-generated catch block
  14.                         e.printStackTrace();
  15.                     }
  16.                 }
  17.             }
  18.         }.start();
  19.         new Thread(){
  20.             @Override
  21.             public void run() {
  22.                 // TODO Auto-generated method stub
  23.                 while(true){
  24.                     try {
  25.                         sleep(1000);
  26.                         p.print2();
  27.                     } catch (Exception e) {
  28.                         // TODO Auto-generated catch block
  29.                         e.printStackTrace();
  30.                     }
  31.                 }
  32.             }
  33.         }.start();
  34.         new Thread(){
  35.             @Override
  36.             public void run() {
  37.                 // TODO Auto-generated method stub
  38.                 while(true){
  39.                     try {
  40.                         sleep(1000);
  41.                         p.print3();
  42.                     } catch (Exception e) {
  43.                         // TODO Auto-generated catch block
  44.                         e.printStackTrace();
  45.                     }
  46.                 }
  47.             }
  48.         }.start();
  49.     }
  50. }
  51. class Printer{
  52.     private int n = 1;
  53.     public void print1() throws Exception{
  54.         synchronized (this) {
  55.             while(n!=1){
  56.                 this.wait();//等待
  57.             }
  58.             System.out.print("每");
  59.             System.out.print("天");
  60.             System.out.print("进");
  61.             System.out.print("步");
  62.             System.out.print("一");
  63.             System.out.print("点");
  64.             System.out.print("点");
  65.             System.out.println();
  66.             n = 2;
  67.             this.notifyAll();//唤醒其它线程
  68.         }
  69.     }
  70.     public void print2() throws Exception{
  71.         synchronized (this) {
  72.             while(n!=2){
  73.                 this.wait();//等待
  74.             }
  75.             System.out.print("好");
  76.             System.out.print("好");
  77.             System.out.print("学");
  78.             System.out.print("习");
  79.             System.out.println();
  80.             n = 3;
  81.             this.notifyAll();//唤醒其它线程
  82.         }
  83.     }
  84.     public void print3() throws Exception{
  85.         synchronized (this) {
  86.             while(n!=3){
  87.                 this.wait();//等待
  88.             }
  89.             System.out.print("天");
  90.             System.out.print("天");
  91.             System.out.print("向");
  92.             System.out.print("上");
  93.             System.out.println();
  94.             n = 1;
  95.             this.notifyAll();//唤醒其它线程
  96.         }
  97.     }
  98. }
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