package javaBese;
public class ThreadTest {
/*
* 共同点: 他们都是在多线程的环境下,都可以在程序的调用处阻塞指定的毫秒数,并返回。
不同点: Thread.sleep(long)可以不在synchronized的块下调用,而且使用Thread.sleep()不会丢失当前线程对任何对象的同步锁(monitor);
object.wait(long)必须在synchronized的块下来使用,调用了之后失去对object的monitor, 这样做的好处是它不影响其它的线程对object进行操作。
*/
public void thread()
{
System.out.println("I am here!");
Thread thread = new Thread();
Thread thread2 = new Thread();
try {
thread2.sleep(1000);
System.out.println("sleep 1秒后,I am come back!");
thread2.start();
System.out.println("thread is start");
thread2.stop();
System.out.println("thread is stop");
synchronized (thread)//如果使用wait,就必须synchronized来同步对象
{
System.out.println("");
for (int i = 0; i < 5; i++) {
thread.notify();//必须要放在synchronized方法的里面
System.out.println("First,notify thread");
thread.wait(1000);
System.out.println("wait 1秒后,I am come back!");
}
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public static void main(String[] args) {
ThreadTest threadTest = new ThreadTest();
threadTest.thread();
}
}
/*
* 复杂应用
程序会启动20个线程,20个线程都使用同一个sync的object(名字为SYNC)。 线程启动代码如下:
Java代码
final TC[] ts = new TC[20];
for (int i = 0; i < ts.length; i++) {
TC target = new TC("TC " + i, SYNC1);
Thread thread = new Thread(target);
ts[i] = target;
thread.start();
}
final TC[] ts = new TC[20];
for (int i = 0; i < ts.length; i++) {
TC target = new TC("TC " + i, SYNC1);
Thread thread = new Thread(target);
ts[i] = target;
thread.start();
}
------------------------------------------------------------
接下来马上启动另外一个线程用于做notify操作。
Java代码
// 一个用于停止的Thread
new Thread(new Runnable() {
public void run() {
synchronized (SYNC1) {
int i = 10;
while (i > 0) {
System.out.println("Now will notify the thread " + i);
ts[i].notifySelf();
try {
SYNC1.wait(10000);
} catch (InterruptedException e) {
e.printStackTrace();
}
i--;
}
}
}
}).start();
// 一个用于停止的Thread
new Thread(new Runnable() {
public void run() {
synchronized (SYNC1) {
int i = 10;
while (i > 0) {
System.out.println("Now will notify the thread " + i);
ts[i].notifySelf();
try {
SYNC1.wait(10000);
} catch (InterruptedException e) {
e.printStackTrace();
}
i--;
}
}
}
}).start();
------------------------------------------------------------
Java代码
启动的TC线程代码如下:
class TC implements Runnable {
private final String name;
private final Object sync;
private boolean isRunning = false;
public TC(String name, Object sync) {
this.name = name;
this.sync = sync;
}
public void run() {
synchronized (sync) {
while (true) {
// 每个线程默认都加入线程池排队。这样有助于打乱线程在主线程中启动的顺序,方便后面的观测。
if (!isRunning) {
try {
sync.wait(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
isRunning = true;
}
System.out.println(name + " Running .......");
try {
sync.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}// Wait 1 second
}
}
}
public void notifySelf() {
synchronized (sync) {
System.out.println("Coming to notify the thread " + name);
sync.notify();
}
}
}
启动的TC线程代码如下:
class TC implements Runnable {
private final String name;
private final Object sync;
private boolean isRunning = false;
public TC(String name, Object sync) {
this.name = name;
this.sync = sync;
}
public void run() {
synchronized (sync) {
while (true) {
// 每个线程默认都加入线程池排队。这样有助于打乱线程在主线程中启动的顺序,方便后面的观测。
if (!isRunning) {
try {
sync.wait(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
isRunning = true;
}
System.out.println(name + " Running .......");
try {
sync.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}// Wait 1 second
}
}
}
public void notifySelf() {
synchronized (sync) {
System.out.println("Coming to notify the thread " + name);
sync.notify();
}
}
}
---------------------------分割线---------------------------------
输出日志如下(//部分是我加的注释,不是实际输出):
Now will notify the thread 10 //首先试着notify第10个TC
Coming to notify the thread TC 10 // 也确实调用了SYNC的notify操作,但是因为当前还没有任何线程在wait,所以这个notify信号就被丢弃掉了。这个notify过去就过去了。不会影响后面的任何操作了。
TC 1 Running .......
TC 5 Running .......
TC 0 Running .......
TC 2 Running .......
TC 4 Running .......
TC 6 Running .......
TC 8 Running .......
TC 10 Running .......
TC 12 Running .......
TC 14 Running .......
TC 7 Running .......
TC 9 Running .......
TC 11 Running .......
TC 13 Running .......
TC 15 Running .......
TC 17 Running .......
TC 3 Running .......
TC 18 Running .......
TC 16 Running .......
TC 19 Running ....... //启动20线程,这20个线程启动的顺序已经被打乱了。不会从头到尾1-20的启动,而是如log显示1,5,0,2,4,6,8,10,12,14.........
//每个线程启动后会被wait(). wait的顺序是1,5,0,2,4,6,8,10,12,14.........
Now will notify the thread 9
Coming to notify the thread TC 9
TC 1 Running .......
Now will notify the thread 8
Coming to notify the thread TC 8
TC 5 Running .......
Now will notify the thread 7
Coming to notify the thread TC 7
TC 0 Running .......
Now will notify the thread 6
Coming to notify the thread TC 6
TC 2 Running .......
Now will notify the thread 5
Coming to notify the thread TC 5
TC 4 Running .......
Now will notify the thread 4
Coming to notify the thread TC 4
TC 6 Running .......
Now will notify the thread 3
Coming to notify the thread TC 3
TC 8 Running .......
Now will notify the thread 2
Coming to notify the thread TC 2
TC 10 Running .......
Now will notify the thread 1
Coming to notify the thread TC 1
TC 12 Running .......
//总共10个notify操作,但是因为启动的时候一个notify因为没有任何wait的线程给丢弃了,所以,这里只有9个notify起到了作用。他们是按照进入pool的顺序排队给notify。
//一个notify操作仅仅激活一个wait队列中的第一个线程。一对一操作。
-------------------------------分割线------------------------------
使用notifyAll代替notify。
日志输出:
Now will notify the thread 10
Coming to notify the thread TC 10 //第一个notifyAll的操作还是被丢弃了
TC 0 Running .......
TC 1 Running .......
TC 3 Running .......
TC 5 Running .......
TC 7 Running .......
TC 9 Running .......
TC 11 Running .......
TC 13 Running .......
TC 15 Running .......
TC 17 Running .......
TC 19 Running .......
TC 2 Running .......
TC 4 Running .......
TC 6 Running .......
TC 8 Running .......
TC 10 Running .......
TC 12 Running .......
TC 14 Running .......
TC 16 Running .......
TC 18 Running .......
Now will notify the thread 9
Coming to notify the thread TC 9 //一个notifyAll的操作notify所以正在wait的线程。
TC 0 Running .......
TC 1 Running .......
TC 3 Running .......
TC 5 Running .......
TC 7 Running .......
TC 9 Running .......
TC 11 Running .......
TC 2 Running .......
TC 13 Running .......
TC 15 Running .......
TC 4 Running .......
TC 17 Running .......
TC 19 Running .......
TC 6 Running .......
TC 8 Running .......
TC 10 Running .......
TC 12 Running .......
TC 14 Running .......
TC 16 Running .......
TC 18 Running .......
* */
转自:http://hi.baidu.com/billgon/blog/item/503fb458997888cc9c820490.html