/*** 此类用于演示锁重入的概念* * 可重入锁：自己可以再次获取自己的内部锁。例如一个线程获得了某个对象的锁，此时这个对象还没有释放，当其再次想要获取这个对象的锁的时候还是可以获得，* 如果不可锁重入的话，则会造成死锁，并且当存在父子集成关系时，子类完全可以通过"可重入锁"调用父类的同步方法* * @Description* @author niepei* @date 2017年4月25日 下午3:52:41* @version V1.3.1*/
public class LockReentry {public synchronized void service1() {System.out.println("service1");this.service2();}public synchronized void service2() {System.out.println("service2");this.service3();}public synchronized void service3() {System.out.println("service3");}public static void main(String[] args) {Thread thread = new Thread() {@Overridepublic void run() {LockReentry service = new LockReentry();service.service1();}};thread.start();}
}

public class DeadThread implements Runnable {private String username;private Object lock1 = new Object();private Object lock2 = new Object();public void setFlag(String username) {this.username = username;}@Overridepublic void run() {if (username.equals("a")) {synchronized (lock1) {System.out.println("username = " + username);try {Thread.sleep(1000);} catch (Exception e) {e.printStackTrace();}synchronized (lock2) {System.out.println("按 lock1 -> lock2 代码顺序执行了");}}}if (username.equals("b")) {synchronized (lock2) {System.out.println("username = " + username);try {Thread.sleep(1000);} catch (Exception e) {e.printStackTrace();}synchronized (lock1) {System.out.println("按 lock2 -> lock1 代码顺序执行了");}}}}public static void main(String[] args) throws InterruptedException {DeadThread dt = new DeadThread();dt.setFlag("a");Thread a = new Thread(dt);a.setName("A");a.start();Thread.sleep(1000);dt.setFlag("b");Thread b = new Thread(dt);b.setName("B");b.start();}}运行结果为：
username = a
username = b

package cn.com.thread;import java.util.concurrent.locks.ReentrantReadWriteLock;public class ReadWriteLock {private ReentrantReadWriteLock lock = new ReentrantReadWriteLock();public void read() {try {lock.readLock().lock();System.out.println(Thread.currentThread().getName() + "在" + System.currentTimeMillis() / 1000 + "时刻获得了读锁");Thread.sleep(1000);} catch (Exception e) {e.printStackTrace();} finally {lock.readLock().unlock();}}public void write() {try {lock.writeLock().lock();System.out.println(Thread.currentThread().getName() + "在" + System.currentTimeMillis() / 1000 + "时刻获得了写锁");Thread.sleep(1000);} catch (Exception e) {e.printStackTrace();} finally {lock.writeLock().unlock();}}public static void main(String[] args) {//读读共享
        testReadReadLock();/*** 打印结果如下：* R1在1493257634时刻获得了读锁* R2在1493257634时刻获得了读锁*///读写互斥
        testReadWriteLock();/*** 打印结果如下： * R在1493258342时刻获得了读锁 * W在1493258343时刻获得了写锁*///写写互斥
        testWriteWriteLock();/*** 打印结果如下： * W1在1493259822时刻获得了写锁* W2在1493259823时刻获得了写锁*/}public static void testReadReadLock() {ReadWriteLock lock = new ReadWriteLock();new ReadThread("R1",lock).start();new ReadThread("R2",lock).start();}public static void testReadWriteLock() {ReadWriteLock lock = new ReadWriteLock();new ReadThread("R",lock).start();new WriteThread("W",lock).start();}public static void testWriteWriteLock() {ReadWriteLock lock = new ReadWriteLock();new WriteThread("W1",lock).start();new WriteThread("W2",lock).start();}}
/*** 读线程* @Description * @author niepei* @date 2017年4月27日 上午10:05:57 * @version V1.3.1*/
class ReadThread extends Thread {private ReadWriteLock lock;public ReadThread(String name, ReadWriteLock lock) {super(name);this.lock = lock;}@Overridepublic void run() {lock.read();}
}
/*** 写线程* @Description * @author niepei* @date 2017年4月27日 上午10:05:46 * @version V1.3.1*/
class WriteThread extends Thread {private ReadWriteLock lock;public WriteThread(String name, ReadWriteLock lock) {super(name);this.lock = lock;}@Overridepublic void run() {lock.write();}
}