Linux系统中Java的线程唤醒

在Linux系统中，Java线程的唤醒主要涉及到线程同步和线程间通信

1. synchronized关键字：synchronized是Java中的一个关键字，用于控制多个线程对共享资源的访问。当一个线程进入一个synchronized代码块时，它会获取该对象的锁。其他试图进入该代码块的线程将被阻塞，直到第一个线程释放锁。当线程完成synchronized代码块后，它需要显式地释放锁，以便其他线程可以继续执行。

示例：

public class JavaThreadWakeup {
    public static void main(String[] args) {
        Object lock = new Object();

        Thread t1 = new Thread(() -> {
            synchronized (lock) {
                System.out.println("Thread 1: Holding the lock.");
                try {
                    Thread.sleep(2000); // Sleep for 2 seconds to simulate some work.
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("Thread 1: Releasing the lock.");
            }
        });

        Thread t2 = new Thread(() -> {
            synchronized (lock) {
                System.out.println("Thread 2: Waiting for the lock.");
                try {
                    lock.wait(); // Wait for Thread 1 to release the lock.
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("Thread 2: Holding the lock.");
            }
        });

        t1.start();
        t2.start();
    }
}

2. wait()和notify()方法：wait()和notify()方法是Java中的Object类的方法，用于线程间通信。当一个线程调用一个对象的wait()方法时，它会释放该对象的锁并进入等待状态。当另一个线程调用同一个对象的notify()方法时，所有等待该对象锁的线程将被唤醒。

示例：

public class JavaThreadWakeup {
    public static void main(String[] args) {
        final Object lock = new Object();

        Thread t1 = new Thread(() -> {
            synchronized (lock) {
                System.out.println("Thread 1: Holding the lock.");
                try {
                    Thread.sleep(2000); // Sleep for 2 seconds to simulate some work.
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("Thread 1: Notifying Thread 2.");
                lock.notify(); // Notify Thread 2 to wake up.
            }
        });

        Thread t2 = new Thread(() -> {
            synchronized (lock) {
                System.out.println("Thread 2: Waiting for the lock.");
                try {
                    lock.wait(); // Wait for Thread 1 to notify.
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("Thread 2: Holding the lock.");
            }
        });

        t1.start();
        t2.start();
    }
}

在这两个示例中，我们使用了synchronized关键字和wait()、notify()方法来实现线程唤醒。请注意，这些方法必须在同步代码块或同步方法中使用，否则会抛出IllegalMonitorStateException异常。