Java多线程编程7--拾遗增补--线程组

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    可以把线程归属到某一个线程组中，线程组中可以有线程对象，也可以有线程组，组中还可以有线程。这样的组织结构有些类似于树的形式，如图所示。

    线程组的作用是，可以批量的管理线程或线程组对象，有效地对线程或线程组对象进行组织。

1、线程对象关联线程组：1级关联

    所谓的1级关联就是父对象中有子对象，但并不创建子孙对象。这种情况经常出现在开发中，比如创建一些线程时，为了有效地对这些线程进行组织管理，通常的情况下是创建一个线程组，然后再将部分线程归属到该组中。这样的处理可以对零散的线程对象进行有效的组织与规划。

public class MyThread1 extends Thread {
    @Override
    public void run() {
        try{
            while(!Thread.currentThread().isInterrupted()) {
                System.out.println("ThreadName="
                        + Thread.currentThread().getName());
                Thread.sleep(4000);
            }
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

public class MyThread2 extends Thread{
    @Override
    public void run() {
        try{
            while(!Thread.currentThread().isInterrupted()) {
                System.out.println("ThreadName="
                        + Thread.currentThread().getName());
                Thread.sleep(4000);
            }
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

public class Run {
    public static void main(String[] args) throws InterruptedException {
        MyThread1 t1 = new MyThread1();
        MyThread2 t2 = new MyThread2();
        ThreadGroup group = new ThreadGroup("lcw的线程组");

        Thread aThread = new Thread(group, t1);
        Thread bThread = new Thread(group, t2);
        aThread.start();
        bThread.start();

        System.out.println("活动的线程数为：" + group.activeCount());
        Thread.sleep(1000);
        System.out.println("线程组的名称为：" + group.getName());
    }
}

2、线程对象关联线程组:多级关联

    所谓的多级关联就是父对象中有子对象，子对象中再创建子对象，也就是出现子孙对象的效果了。但是此种写法在开发中不太常见，如果线程树结构设计得非常复杂反而不利于线程对象的管理，但JDK却提供了支持多级关联的线程树结构。

/**
 * 在main组中添加一个线程组A,然后在这个A组中添加线程对象X和Y
 * 方法activeGroupCount()和activeCount()的值不是固定的，
 * 是系统中环境的一个快照
 */
public class Run {
    public static void main(String[] args) throws InterruptedException {
        ThreadGroup mainGroup = Thread.currentThread().getThreadGroup();
        //ThreadGroup(父线程组，子线程组名）
        ThreadGroup group = new ThreadGroup(mainGroup, "AA");

        Runnable runnable = new Runnable() {
            public void run() {
                try {
                    System.out.println("runMethod!");
                    Thread.sleep(1000); //线程必须在运行状态才可以受组管理
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        };

        Thread newThread = new Thread(group, runnable);
        newThread.setName("X");
        newThread.start(); //线程必须启动然后才归到组A中

        Thread newThread2 = new Thread(group, runnable);
        newThread2.setName("Y");
        newThread2.start(); //线程必须启动然后才归到组A中

        ///
        ThreadGroup[] listGroup = new ThreadGroup[Thread.currentThread()
                .getThreadGroup().activeGroupCount()];
        Thread.currentThread().getThreadGroup().enumerate(listGroup);
        System.out.println("main线程中有多少个子线程组：" + listGroup.length
                +", 名字为：" +listGroup[0].getName()
                +",这个子线程组有多少个线程：" + listGroup[0].activeCount());

        Thread[] listThread = new Thread[listGroup[0].activeCount()];
        listGroup[0].enumerate(listThread);
        System.out.println(listThread[0].getName());
        System.out.println(listThread[1].getName());
    }
}

3、线程组自动归属特性

    自动归属就是自动归到当前线程组中。

/**
 * 方法activeGroupCount()取得当前线程组对象中的子线程组数量
 * 方法enumerate()的作用是将线程组中的子线程以复数的形式
 *     拷贝到ThreadGroup[]数组对象中
 */
public class Run {
    public static void main(String[] args) throws InterruptedException {
        System.out.println("A处线程名：" + Thread.currentThread().getName()
                + ",所属的线程组名为："+Thread.currentThread().getThreadGroup().getName()
                + ", 中有线程组数量："+Thread.currentThread().getThreadGroup().activeGroupCount());
        ThreadGroup group = new ThreadGroup("新的组"); //自动加到main组中
        System.out.println("B处线程名：" + Thread.currentThread().getName()
                + ",所属的线程组名为："+Thread.currentThread().getThreadGroup().getName()
                + ", 中有线程组数量："+Thread.currentThread().getThreadGroup().activeGroupCount());

        ThreadGroup[] threadGroups = new ThreadGroup[Thread.currentThread()
                .getThreadGroup().activeGroupCount()];
        Thread.currentThread().getThreadGroup().enumerate(threadGroups);

        System.out.println("第一个线程组名称为：" +threadGroups[0].getName());
    }
}

4、获取根线程组

public class Run {
    public static void main(String[] args) throws InterruptedException {
        System.out.println("线程："+Thread.currentThread().getName()
                +",所在的线程组名为："+Thread.currentThread().getThreadGroup().getName());

        System.out.println("main线程所在的线程组的父线程组的名称是："
                +Thread.currentThread().getThreadGroup().getParent().getName());

        System.out.println("main线程所有的线程组的父线程组的你线程组的名称是："
                +Thread.currentThread().getThreadGroup().getParent().getParent().getName());
    }
}

5、线程组里加线程组

public class Run {
    public static void main(String[] args) throws InterruptedException {
        System.out.println("线程组名称："
                + Thread.currentThread().getThreadGroup().getName());
        System.out.println("线程组中活动的线程数量："
                +Thread.currentThread().getThreadGroup().activeCount());
        System.out.println("线程组中线程组的数据--加之前："
                +Thread.currentThread().getThreadGroup().activeGroupCount());

        ThreadGroup newGroup = new ThreadGroup(Thread.currentThread()
                .getThreadGroup(), "newGroup");
        System.out.println("线程组中线程组的数量--加之后："
                +Thread.currentThread().getThreadGroup().activeGroupCount());
        System.out.println("父线程组名称："
                +Thread.currentThread().getThreadGroup().getParent().getName());
    }
}

6、组内的线程批量停止

public class MyThread extends Thread {
    public MyThread(ThreadGroup group, String name) {
        super(group, name);
    }

    @Override
    public void run() {
        System.out.println("ThreadName=" + Thread.currentThread().getName()
                +",准备开始死循环了");
        while(!this.isInterrupted()){
        }
        System.out.println("ThreadName=" + Thread.currentThread().getName()
                +",结束了");
    }
}

public class Run {
    public static void main(String[] args) throws InterruptedException {
        ThreadGroup group = new ThreadGroup("myThreadGroup");
        for (int i=0; i<3; i++) {
            MyThread thread = new MyThread(group, "线程"+(i+1));
            thread.start();
        }
        Thread.sleep(1000);
        group.interrupt();
        System.out.println("调用了interrupt方法");
    }
}

7、递归与非递归取得组内对象

public class Run {
    public static void main(String[] args) throws InterruptedException {
        ThreadGroup mainGroup = Thread.currentThread().getThreadGroup();
        ThreadGroup groupA = new ThreadGroup(mainGroup, "AA");

        Runnable runnable = new Runnable() {
            public void run() {
                try {
                    System.out.println("runMethod!");
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        };

        ThreadGroup groupB = new ThreadGroup(groupA, "BB");
        //分配空间，但不一定全部用完
        ThreadGroup[] listGroup1 = new ThreadGroup[Thread.currentThread()
                .getThreadGroup().activeGroupCount()];
        //传入true是递归取得子组及子孙组
        Thread.currentThread().getThreadGroup().enumerate(listGroup1, true);
        for (int i=0; i<listGroup1.length; i++) {
            if (listGroup1[i] != null){
                System.out.println("--"+listGroup1[i].getName());
            }
        }
        ThreadGroup[] listGroup2 = new ThreadGroup[Thread.currentThread()
                .getThreadGroup().activeGroupCount()];
        Thread.currentThread().getThreadGroup().enumerate(listGroup2, false);
        for (int i=0; i<listGroup2.length; i++) {
            if (listGroup2[i] != null){
                System.out.println("**" +listGroup2[i].getName());
            }
        }
    }
}

Java多线程编程7--拾遗增补--线程组

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原文地址：http://blog.csdn.net/ochangwen/article/details/51353620