Java多线程编程总结

线程基础：

当创建线程时，会为非static对象各自申请内存空间

卖票程序：

线程的优先级用1-10之间的整数表示，数值越大优先级越高，默认的优先级为5。

pupublic class Main {static int ticket = 10;static Runnable mRunnable = new Runnable() {@Overridepublic void run() {// TODO Auto-generated method stubwhile (true) {synchronized (this) {if (ticket > 0) {try {Thread.sleep(1000);System.out.println(Thread.currentThread().getName()+ "卖出票-->" + ticket--);} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}} else {break;}}}}};public static void main(String[] args) {Thread t1 = new Thread(mRunnable, "线程， A\t");Thread t2 = new Thread(mRunnable, "线程， B\t");t1.setPriority(1);t2.setPriority(10);t1.start();t2.start();}
}

卖票程序（两线程各自有自己的票仓库）

将ticket设为non-static

public class MyThread implements Runnable {int ticket = 100;@Overridepublic void run() {// TODO Auto-generated method stubwhile (true) {synchronized (this) {if (ticket > 0) {try {Thread.sleep(10);System.out.println(Thread.currentThread().getName() + "卖出票-->" + ticket--);} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}} else {break;}}}}public static void main(String[] args) {Runnable run1 = new MyThread();Runnable run2 = new MyThread();Thread t1 = new Thread(run1,"线程   A\t");Thread t2 = new Thread(run2,"线程   B\t");t1.start();t2.start();try {t1.join(); System.out.println(t1.getName() + "卖完票");t2.join();System.out.println(t2.getName() + "卖完票");} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}}
}

一个死锁案例：Java：多线程死锁

public class LockDemo implements Runnable{private static Object object1 = new Object();private static Object object2 = new Object();private int flag = 0;public static void main(String[] args) throws InterruptedException {LockDemo run0 = new LockDemo();LockDemo run1 = new LockDemo();    run0.flag = 1;    //here    run1.flag = 2;    //Thread thread1 = new Thread(run0);Thread thread2 = new Thread(run1);thread1.start();thread2.start();}@Overridepublic void run(){System.out.println(flag);if (flag == 1){synchronized (object1){System.out.println("线程 ： " + flag + "锁定obj1，休息0.5秒后锁定obj2去！");try{Thread.sleep(500);}catch (Exception e){e.printStackTrace();}synchronized (object2){System.out.println("线程 : " + flag + "访问 object2");}}}if (flag == 2){synchronized (object2){System.out.println("线程 ： " + flag + "锁定obj2，休息0.5秒后锁定obj1去！");try{Thread.sleep(500);}catch (Exception e){e.printStackTrace();}synchronized (object1){System.out.println("线程 : " + flag + "访问object1");}}}}
}

结果：

2线程 ： 2锁定obj2，休息0.5秒后锁定obj1去！1线程 ： 1锁定obj1，休息0.5秒后锁定obj2去！

对象锁、notifyAll、notify、wait

wait()方法 
在其他线程调用对象的notify或notifyAll方法前，导致当前线程等待。线程会释放掉它所占有的“锁标志”，从而使别的线程有机会抢占该锁。 
唤醒当前对象锁的等待线程使用notify或notifyAll方法,wait() 和notify()必须在synchronized函数或synchronized　block中进行调用。

Calculator.java:

//计算线程
public class Calculator extends Thread {private int total;public int getTotal() {return total;}public void run() {synchronized (this) {for (int i = 0; i < 10; i++) {total += i;}// 通知所有在此对象上等待的线程notifyAll();}}
}

ReaderResult.java:

public class ReaderResult extends Thread {Calculator c;public ReaderResult(Calculator c) {this.c = c;}public void run() {synchronized (c) {try {System.out.println(Thread.currentThread() + "等待计算结果。。。");c.wait();} catch (InterruptedException e) {e.printStackTrace();}System.out.println(Thread.currentThread() + "计算结果为：" + c.getTotal());}}public static void main(String[] args) {// 启动5个线程，分别获取计算结果Calculator calculator = new Calculator();for (int i = 0; i < 5; i++) {new ReaderResult(calculator).start();}// 启动计算线程calculator.start();}
}

结果：

Thread[Thread-1,5,main]等待计算结果。。。Thread[Thread-2,5,main]等待计算结果。。。Thread[Thread-3,5,main]等待计算结果。。。Thread[Thread-5,5,main]等待计算结果。。。Thread[Thread-4,5,main]等待计算结果。。。Thread[Thread-1,5,main]计算结果为：45Thread[Thread-4,5,main]计算结果为：45Thread[Thread-5,5,main]计算结果为：45Thread[Thread-3,5,main]计算结果为：45Thread[Thread-2,5,main]计算结果为：45

线程jion方法：等待该线程终止。等待调用join方法的线程结束，再继续执行。

public class Main {static class MyThread implements Runnable {@Overridepublic void run() {// TODO Auto-generated method stubfor (int i = 0; i < 5; i++) {try {Thread.sleep(1000);show("XIXI RUN->slower and slower");} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}}public static void main(String args[]) {Runnable mRunnable = new MyThread();Thread t1 = new Thread(mRunnable, "xixi");t1.start();try {t1.join();} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}show("MAIN RUN->CAN YOU BE FAST");}private static void show(String str) {System.out.println(str);}
}

结果：

XIXI RUN->slower and slowerXIXI RUN->slower and slowerXIXI RUN->slower and slowerXIXI RUN->slower and slowerXIXI RUN->slower and slowerMAIN RUN->CAN YOU BE FAST