Java多线程:线程同步——实验5

原文地址: http://blog.csdn.net/huang_xw/article/details/7318554

/** * @Description: 线程1访问线程安全对象StringBuffer的实例, 线程2要访问时该对象则会出现阻塞现象. * @author snoopy * @blog http://blog.csdn.net/huang_xw */package basic.b_syn;import org.apache.log4j.Logger;public class TestSynE {private static Logger logger = Logger.getLogger(TestSynE.class);StringBuffer sb = new StringBuffer("初始字符串+");// 线程1static class T1 implements Runnable {TestSynE s;public T1(TestSynE sameObj) {this.s = sameObj;}// 线程1访问方法syn1()public void run() {logger.debug("启动线程1...........");s.syn1();logger.debug("退出线程1...........");}}// 线程2static class T2 implements Runnable {TestSynE s;public T2(TestSynE sameObj) {this.s = sameObj;}// 线程2访问方法syn2()public void run() {logger.debug("启动线程2...........");s.syn2();logger.debug("退出线程2...........");}}public void syn1() {String threadStr = Thread.currentThread().getName();logger.debug("▲▲▲▲▲▲" + threadStr + "开始访问方法syn1()");try {synchronized (sb) {logger.debug(threadStr + "正在访问对象sb");sb.append("线程1加入的字符串+");// 用休眠模拟一个耗时过程Thread.sleep(5000);logger.debug(threadStr + "休眠结束");logger.debug("此时字符串为: " + sb.toString());}} catch (InterruptedException e) {e.printStackTrace();}logger.debug("▲▲▲▲▲▲" + threadStr + "退出方法syn1()");}public void syn2() {String threadStr = Thread.currentThread().getName();logger.debug("●●●●●●" + threadStr + "开始访问方法syn2()");sb.append("线程2加入的字符串+");logger.debug("此时字符串为: " + sb.toString());logger.debug("●●●●●●" + threadStr + "退出方法syn2()");}public static void main(String[] args) {// 这是多线程要访问的同一个对象TestSynE sameObj = new TestSynE();// 线程1访问同步方法syn1(), 线程2同样也访问同步方法syn2().Thread t1 = new Thread(new T1(sameObj), "线程1");Thread t2 = new Thread(new T2(sameObj), "线程2");t1.start();// sleep是为保证线程1先开始运行, 首先访问StringBuffer的实例.try {Thread.sleep(50);} catch (InterruptedException e) {e.printStackTrace();}t2.start();}}

执行结果:

0    [线程1] DEBUG basic.b_syn.TestSynE - 启动线程1...........0    [线程1] DEBUG basic.b_syn.TestSynE - ▲▲▲▲▲▲线程1开始访问方法syn1()0    [线程1] DEBUG basic.b_syn.TestSynE - 线程1正在访问对象sb49   [线程2] DEBUG basic.b_syn.TestSynE - 启动线程2...........49   [线程2] DEBUG basic.b_syn.TestSynE - ●●●●●●线程2开始访问方法syn2()5000 [线程1] DEBUG basic.b_syn.TestSynE - 线程1休眠结束5001 [线程1] DEBUG basic.b_syn.TestSynE - 此时字符串为: 初始字符串+线程1加入的字符串+5001 [线程1] DEBUG basic.b_syn.TestSynE - ▲▲▲▲▲▲线程1退出方法syn1()5001 [线程2] DEBUG basic.b_syn.TestSynE - 此时字符串为: 初始字符串+线程1加入的字符串+线程2加入的字符串+5001 [线程1] DEBUG basic.b_syn.TestSynE - 退出线程1...........5001 [线程2] DEBUG basic.b_syn.TestSynE - ●●●●●●线程2退出方法syn2()5001 [线程2] DEBUG basic.b_syn.TestSynE - 退出线程2...........