java_Thread.rar_java 多线程_java多线程

6.1 Java多线程机制 6.1.1基本概念 线程控制方法 public class Thread implements Runnable { public final static int MIN_PRIORITY; public final static int NORM_PRIORITY; public final static int MAX_PRIORITY; public Thread(); public Thread(Runnable target); public Thread(ThreadGroup group, Runnable target); public Thread(String name); public Thread(ThreadGroup group, String name); public Thread(Runnable target, String name); public Thread(ThreadGroup group, Runnable target, String name); public void run(); public synchronized native void start(); public final void stop(); public final synchronized void stop(Throwable o); public static native void yield(); public static native void sleep(long millis) throws InterruptedException; public static void sleep(long millis, int nanos) throws InterruptedException public final void suspend(); public final void resume(); public final synchronized void join(long millis) throws InterruptedException; public final synchronized void join(long millis, int nanos)throws InterruptedException; public final void join() throws InterruptedException; public void interrupt(); public static boolean interrupted(); public boolean isInterrupted(); public void destroy(); public final native boolean isAlive(); public final void setPriority(int newPriority); public final int getPriority(); public final void setName(String name); public final String getName(); public final ThreadGroup getThreadGroup(); public static native Thread currentThread(); public static int activeCount(); public static int enumerate(Thread tarray[]); public native int countStackFrames(); public static void dumpStack(); public final void setDaemon(boolean on); public final boolean isDaemon(); public void checkAccess(); public String toString(); } ____________________________________________________________ 6.1.2多线程实现方法 例1：下面程序演示如何用生成Thread子类的方法来创建新线程。 //ThreadTest1.java public class ThreadTest1 { ThreadTest1() { FirstThread first = new FirstThread(); SecondThread second = new SecondThread(); first.start(); second.start(); } public static void main(String[] args) { new ThreadTest1(); } } class FirstThread extends Thread { public void run() { try { System.out.println("First thread starts running."); for(int i=0; i<10; i++) { System.out.println("First " + i); sleep(1000); } System.out.println("First thread finishes running."); } catch (InterruptedException e) {} } } class SecondThread extends Thread { public void run() { try { System.out.println("\tSecond thread starts running."); for(int i=0; i<10; i++) { System.out.println("\tSecond " + i); sleep(1000); } System.out.println("\tSecond thread finishes running."); } catch (InterruptedException e) {} } } 程序设计了两个线程FirstThread类和SecondThread类，它们都是Thread类 的子类覆盖了run()方法，在其中分别进行打印数值的工作。 除了这两个线程 外，还有一个线程在执行，就是启动类线程，称它为主线程，它负责生成另外 两个线程，再用start()方法启动这两个线程。 线程first和second启动后，并发执行。观察执行结果会发现两个线程交替打印数据，而不是一个线程完成了所有打印工作后，另一个线程才开始打印工作，这就是多线程的本质。 提示：线程在调用Thread类方法sleep()睡眠时，有可能产生异常，要求 应用程序用try-catch捕获这个异常，如果不用try-catch，程序将出错。 某次的运行结果： First thread finishes running. First 0 Second thread starts running. Second 0 Second 1 First 1 First 2 Second 2 First 3 Second 3 First 4 Second 4 Second 5 First 5 First 6 Second 6 First 7 Second 7 First 8 Second 8 First 9 Second 9 First thread finishes running. Second thread finishes ________________________________________________ 例2：下面程序演示如何用生成Thread子类的方法来创建新线程。 //ThreadTest2.java public class ThreadTest2 { ThreadTest2() { FirstThread first = new FirstThread(); SecondThread second = new SecondThread(); first.start(); second.start(); try { first.join(); System.out.println("Waiting for first thread to finish..."); System.out.println("Waking up second thread..."); second.resume(); } catch (InterruptedException e) {} } public static void main(String[] args) { new ThreadTest2(); } } class FirstThread extends Thread { public void run() { try { System.out.println("First thread STARTS running."); for(int i=0; i<10; i++) { System.out.println("First " + i); sleep(1000); } System.out.println("First thread FINISHES running."); } catch (InterruptedException e) {} } } class SecondThread extends Thread { public void run() { try { System.out.println("\tSecond thread STARTS running."); for(int i=0; i<10; i++) { if(i== 4) suspend(); System.out.println("\tSecond " + i); sleep(1000); } System.out.println("\tSecond thread FINISHES running."); } catch (InterruptedException e) {} } } 程序仍然使用两个线程打印数据，不同的是second线程在打印数据过程中，发现是数值4，则调用suspend()方法，暂停本身的执行。 主线程用join()方法等线程first执行结束后，用resume()方法来唤醒second线程，second线程被唤醒后，将继续完成打印工作。 提示：join()也将出现InterruptedException异常，所以必须捕获异常。 某次的运行结果： First thread STARTS running. First 0 Second thread STARTS running. Second 0 First 1 Second 1 First 2 Second 2 First 3 Second 3 First 4 First 5 First 6 First 7 First 8 First 9 First thread FINISHES running. Waiting for first thread to finish... Waking up second thread... Second 4 Second 5 Second 6 Second 7 Second 8 Second 9 Second FINISHES finishes ____________________________________________________________ 例3：下面的程序说明如何用接口来创建线程。 //RunTest.java public class RunTest { RunTest() { FirstThread first = new FirstThread(); SecondThread second = new SecondThread(); Thread thread1 = new Thread(first); Thread thread2 = new Thread(second); thread1.start(); thread2.start(); } public static void main(String[] args) { new RunTest(); } } class FirstThread implements Runnable { public void run() { try { System.out.println("First thread starts running."); for(int i=0; i<10; i++) { System.out.println("First " + i); Thread.sleep(1000); } System.out.println("First thread finishes running."); } catch (InterruptedException e) {} } } class SecondThread implements Runnable { public void run() { try { System.out.println("\tSecond thread starts running."); for(int i=0; i<10; i++) { System.out.println("\tSecond " + i); Thread.sleep(1000); } System.out.println("\tSecond thread finishes running