public interface Lock {
    // 用來獲取鎖，如果鎖已經(jīng)被其他線程獲取，則一直等待，直到獲取到鎖
    void lock();
    // 該方法獲取鎖時(shí)，可以響應(yīng)中斷，比如現(xiàn)在有兩個(gè)線程，一個(gè)已經(jīng)獲取到了鎖，另一個(gè)線程調(diào)用這個(gè)方法正在等待鎖
    //但是此刻又不想讓這個(gè)線程一直在這死等，可以通過調(diào)用線程的Thread.interrupted()方法，來中斷線程的等待過程
    void lockInterruptibly() throws InterruptedException;
    // tryLock方法會(huì)返回bool值，該方法會(huì)嘗試著獲取鎖，如果獲取到鎖，就返回true，如果沒有獲取到鎖，就返回false，
    //但是該方法會(huì)立刻返回，而不會(huì)一直等待
    boolean tryLock();
    // 這個(gè)方法和上面的tryLock差不多是一樣的，只是會(huì)嘗試指定的時(shí)間，如果在指定的時(shí)間內(nèi)拿到了鎖，則會(huì)返回true，
    //如果在指定的時(shí)間內(nèi)沒有拿到鎖，則會(huì)返回false
    boolean tryLock(long time, TimeUnit unit) throws InterruptedException;
    // 釋放鎖
    void unlock();
    // 實(shí)現(xiàn)線程通信，相當(dāng)于wait和notify，后面會(huì)單獨(dú)講解
    Condition newCondition();
}

Lock l = ...;
l.lock();
try {
 // access the resource protected by this lock
} finally {// 必須使用try，最后在finally里面釋放鎖
 l.unlock();
}

public class LockDemo {
    // new一個(gè)鎖對(duì)象，注意此處必須聲明成類對(duì)象，保持只有一把鎖,ReentrantLock是Lock的唯一實(shí)現(xiàn)類
    Lock lock = new ReentrantLock();
    public void readFile(String fileMessage){
        lock.lock();// 上鎖
        try {
            System.out.println(Thread.currentThread().getName()+"得到了鎖，正在讀取文件……");
            for (int i = 0; i< fileMessage.length(); i++){
                System.out.print(fileMessage.charAt(i));
            }
            System.out.println();
            System.out.println("文件讀取完畢！");
        } finally {
            System.out.println(Thread.currentThread().getName()+"釋放了鎖！");
            lock.unlock();
        }
    }
    public static void main(String[] args) {
        LockDemo demo = new LockDemo();
        String fileName = "H:/Java_Workspace_Console/test.txt";
        // 創(chuàng)建若干個(gè)線程
        new Thread(new Runnable() {
            @Override
            public void run() {
                demo.readFile(fileName);
            }
        }).start();
        new Thread(new Runnable() {
            @Override
            public void run() {
                demo.readFile(fileName);
            }
        }).start();
    }
}

public class TryLockDemo {
    // new一個(gè)鎖對(duì)象，注意此處必須聲明成類對(duì)象，保持只有一把鎖,ReentrantLock是Lock的唯一實(shí)現(xiàn)類
    Lock lock = new ReentrantLock();
    public void readFile(String fileMessage){
        // 上鎖
        if (lock.tryLock()) {
            try {
                System.out.println(Thread.currentThread().getName()+"得到了鎖，正在讀取文件……");
                for (int i = 0; i< fileMessage.length(); i++){
                    System.out.print(fileMessage.charAt(i));
                }
                System.out.println();
                System.out.println("文件讀取完畢！");
            } finally {
                System.out.println(Thread.currentThread().getName()+"釋放了鎖！");
                lock.unlock();
            }
        }
    }
    public static void main(String[] args) {
        TryLockDemo demo = new TryLockDemo();
        String fileName = "H:/Java_Workspace_Console/test.txt";
        // 創(chuàng)建若干個(gè)線程
        new Thread(new Runnable() {
            @Override
            public void run() {
                demo.readFile(fileName);
            }
        }).start();
        new Thread(new Runnable() {
            @Override
            public void run() {
                demo.readFile(fileName);
            }
        }).start();
    }
}

public interface ReadWriteLock {
    Lock readLock();
    Lock writeLock();
}

public class SyncReadDemo {
    public synchronized void get(Thread thread) {
        System.out.println("start time:"+System.currentTimeMillis());
        for(int i=0; i<5; i++){
            try {
                Thread.sleep(20);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(thread.getName() + ":正在進(jìn)行讀操作……");
        }
        System.out.println(thread.getName() + ":讀操作完畢！");
        System.out.println("end time:"+System.currentTimeMillis());
    }

    public static void main(String[] args) {
        final SyncReadDemo lock = new SyncReadDemo();
        new Thread(new Runnable() {
            @Override
            public void run() {
                lock.get(Thread.currentThread());
            }
        }).start();

        new Thread(new Runnable() {
            @Override
            public void run() {
                lock.get(Thread.currentThread());
            }
        }).start();
    }
}

public class ReadAndWriteLockDemo {
    ReentrantReadWriteLock lock = new ReentrantReadWriteLock();
    public void get(Thread thread) {
        lock.readLock().lock();
        try{
            System.out.println("start time:"+System.currentTimeMillis());
            for(int i=0; i<5; i++){
                try {
                    Thread.sleep(20);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println(thread.getName() + ":正在進(jìn)行讀操作……");
            }
            System.out.println(thread.getName() + ":讀操作完畢！");
            System.out.println("end time:"+System.currentTimeMillis());
        }finally{
            lock.readLock().unlock();
        }
    }

    public static void main(String[] args) {
        final ReadAndWriteLockDemo lock = new ReadAndWriteLockDemo();
        new Thread(new Runnable() {
            @Override
            public void run() {
                lock.get(Thread.currentThread());
            }
        }).start();

        new Thread(new Runnable() {
            @Override
            public void run() {
                lock.get(Thread.currentThread());
            }
        }).start();
    }
}