Java多线程:线程同步——实验2

原文地址: http://blog.youkuaiyun.com/huang_xw/article/details/7318554

/**
 * @Description: 两个线程(线程1与线程2)访问同一个对象的内同步方法syn
 * 				 结果: 线程1访问对象sameObj的同步方法syn()时, 线程2访问对象sameObj中的同步方法syn()阻塞. 或者线程2访问时, 线程1阻塞.
 * 				 结论: 不同线程访问同一个对象的相同同步方法时, 线程间是互斥的. 
 * @author snoopy
 * @blog http://blog.youkuaiyun.com/huang_xw
 */
package basic.b_syn;

import org.apache.log4j.Logger;

import sun.management.snmp.jvminstr.JvmThreadInstanceEntryImpl.ThreadStateMap;

public class TestSynB {
	private static Logger logger = Logger.getLogger(TestSynB.class);

	// 线程1
	static class T1 implements Runnable {
		TestSynB s;

		public T1(TestSynB sameObj) {
			this.s = sameObj;
		}

		// 线程1访问同步方法syn()
		public void run() {
			logger.debug("启动线程1...........");
			s.syn();
			logger.debug("退出线程1...........");
		}
	}

	// 线程2
	static class T2 implements Runnable {
		TestSynB s;

		public T2(TestSynB sameObj) {
			this.s = sameObj;
		}

		// 线程2访问同步方法syn()
		public void run() {
			logger.debug("启动线程2...........");
			s.syn();
			logger.debug("退出线程2...........");
		}
	}

	// 对象的同步方法
	public synchronized void syn() {
		String threadStr = Thread.currentThread().getName();
		logger.debug("▲▲▲▲▲▲" + threadStr + "开始访问同步方法");
		try {
			logger.debug(threadStr + "正在访问同步方法!!!");
			Thread.sleep(3000);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		logger.debug("▲▲▲▲▲▲" + threadStr + "退出同步方法");
	}

	public static void main(String[] args) {
		// 这是多线程要访问的同一个对象
		TestSynB sameObj = new TestSynB();

		// 线程1访问同步方法syn(), 线程2同样也访问同步方法syn().
		Thread t1 = new Thread(new T1(sameObj), "线程1");
		Thread t2 = new Thread(new T2(sameObj), "线程2");

		t1.start();
		t2.start();
	}
}

执行结果:

0    [线程2] DEBUG basic.b_syn.TestSynB - 启动线程2...........
0    [线程1] DEBUG basic.b_syn.TestSynB - 启动线程1...........
1    [线程2] DEBUG basic.b_syn.TestSynB - ▲▲▲▲▲▲线程2开始访问同步方法
1    [线程2] DEBUG basic.b_syn.TestSynB - 线程2正在访问同步方法!!!
3001 [线程2] DEBUG basic.b_syn.TestSynB - ▲▲▲▲▲▲线程2退出同步方法
3001 [线程1] DEBUG basic.b_syn.TestSynB - ▲▲▲▲▲▲线程1开始访问同步方法
3001 [线程1] DEBUG basic.b_syn.TestSynB - 线程1正在访问同步方法!!!
3001 [线程2] DEBUG basic.b_syn.TestSynB - 退出线程2...........
6001 [线程1] DEBUG basic.b_syn.TestSynB - ▲▲▲▲▲▲线程1退出同步方法
6001 [线程1] DEBUG basic.b_syn.TestSynB - 退出线程1...........