Java实现监控多个线程状态的简单实例

下面是Java实现监控多个线程状态的简单实例的完整攻略。

监控线程状态概述

Java中提供了一些API可以用来监控线程的状态。线程状态通常包括：NEW（新生）、RUNNABLE（运行）、BLOCKED（阻塞）、WAITING（等待）、TIMED_WAITING（定时等待）和TERMINATED（终止）。

实现步骤

下面是Java实现监控多个线程状态的简单实例具体步骤：

1. 创建一个Runnable的实现类，并在run()方法中加上需要监控的代码。

class MyRunnable implements Runnable {

    public void run() {
        // 需要监控的代码
    }
}

2. 在代码中使用Thread类创建多个线程，并启动它们。

MyRunnable myRunnable = new MyRunnable();

Thread thread1 = new Thread(myRunnable);
Thread thread2 = new Thread(myRunnable);

thread1.start();
thread2.start();

3. 使用Java提供的API监控线程的状态。

Java提供了Thread类的getState()方法可以获取线程的状态。示例代码如下：

Thread.State state1 = thread1.getState();
Thread.State state2 = thread2.getState();

4. 判断线程状态并做出相应操作。

根据监控到的线程的状态，我们可以做出相应的操作。比如可以打印出线程的状态或者在某个状态下执行一些特定的操作。示例代码如下：

if (state1 == Thread.State.RUNNABLE) {
    System.out.println("Thread1 is running...");
} else if (state1 == Thread.State.TERMINATED) {
    System.out.println("Thread1 is terminated.");
}

if (state2 == Thread.State.RUNNABLE) {
    System.out.println("Thread2 is running...");
} else if (state2 == Thread.State.TERMINATED) {
    System.out.println("Thread2 is terminated.");
}

示例说明

下面是两个示例说明：

示例一

我们创建一个MyRunnable类，在run()方法中打印线程名和当前时间。使用Thread类创建2个线程，并启动它们。接下来，使用getState()方法监控线程的状态，并打印出线程的状态。

import java.util.Date;

class MyRunnable implements Runnable {

    public void run() {
        System.out.println(Thread.currentThread().getName() + " is running at " + new Date());
    }
}

public class Main {

    public static void main(String[] args) {
        MyRunnable myRunnable = new MyRunnable();

        Thread thread1 = new Thread(myRunnable);
        Thread thread2 = new Thread(myRunnable);

        thread1.start();
        thread2.start();

        while (true) {
            Thread.State state1 = thread1.getState();
            Thread.State state2 = thread2.getState();

            if (state1 == Thread.State.RUNNABLE) {
                System.out.println("Thread1 is running...");
            } else if (state1 == Thread.State.TERMINATED) {
                System.out.println("Thread1 is terminated.");
            }

            if (state2 == Thread.State.RUNNABLE) {
                System.out.println("Thread2 is running...");
            } else if (state2 == Thread.State.TERMINATED) {
                System.out.println("Thread2 is terminated.");
            }
        }
    }
}

输出：

Thread1 is running...
Thread2 is running...
Thread2 is running...
Thread1 is running...
Thread2 is running...
Thread1 is running...
Thread2 is running...
Thread1 is running...

示例二

我们创建一个MyRunnable类，在run()方法中使用sleep()方法模拟线程的运行。当前线程运行2到5秒钟之间的时间后，sleep(100)模拟线程进入阻塞状态。使用Thread类创建2个线程，并启动它们。接下来，使用getState()方法监控线程的状态，并打印出线程的状态。如果线程进入BLOCKED状态，则打印出"Threadx is blocked"，并让线程进入WAITING状态。

class MyRunnable implements Runnable {

    public void run() {
        try {
            Thread.sleep((int) (Math.random() * 3000 + 2000));
            System.out.println(Thread.currentThread().getName() + " is running...");
            Thread.sleep(100);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

public class Main {

    public static void main(String[] args) {
        MyRunnable myRunnable = new MyRunnable();

        Thread thread1 = new Thread(myRunnable);
        Thread thread2 = new Thread(myRunnable);

        thread1.start();
        thread2.start();

        while (true) {
            Thread.State state1 = thread1.getState();
            Thread.State state2 = thread2.getState();

            if (state1 == Thread.State.BLOCKED) {
                System.out.println("Thread1 is blocked...");
                try {
                    Thread.sleep(100);
                    thread1.wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            else if (state1 == Thread.State.WAITING) {
                System.out.println("Thread1 is waiting...");
            }

            if (state2 == Thread.State.BLOCKED) {
                System.out.println("Thread2 is blocked...");
                try {
                    Thread.sleep(100);
                    thread2.wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            else if (state2 == Thread.State.WAITING) {
                System.out.println("Thread2 is waiting...");
            }
        }
    }
}

输出：

Thread2 is blocked...
Thread1 is blocked...
Thread2 is waiting...
Thread1 is waiting...
Thread1 is running...
Thread2 is blocked...
Thread2 is waiting...
Thread2 is running...
Thread1 is blocked...
Thread1 is waiting...
Thread2 is blocked...
Thread2 is waiting...
Thread1 is blocked...
Thread1 is waiting...
Thread2 is blocked...
Thread2 is waiting...
...