import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

public class Lockers {

    public static class LockTest {

        int addtimes = 0;

        public void addValue(double v) {
            System.out.println("LockTest to addValue: " + v + "   "
                    + System.currentTimeMillis());
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
            }
            this.value += v;
            this.addtimes++;
        }

        public double getValue() {
            return this.value;
        }
    }
    public static void testLockTest() throws Exception{
        final LockTest lockTest = new LockTest();
        Runnable task1 = new Runnable(){
            public void run(){
                lockTest.addValue(55.55);
            }
        };
        Runnable task2 = new Runnable(){
            public void run(){
                System.out.println("value: " + lockTest.getValue());
            }
        };
        ExecutorService cachedService = Executors.newCachedThreadPool();
        Future future = null;
        for (int i=0; i<3; i++){
            future = cachedService.submit(task1);
        }
        future.get();
        future = cachedService.submit(task2);
        future.get();
        cachedService.shutdownNow();
    }

    public static class ReadWriteLockTest{
        ReadWriteLock lock = new ReentrantReadWriteLock();
        double value = 0d;
        int addtimes = 0;

        public void addValue(double v) {
            Lock writeLock = lock.writeLock();
            writeLock.lock();
            System.out.println("ReadWriteLockTest to addValue: " + v + "   "
                    + System.currentTimeMillis());
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
            }
            try {
                this.value += v;
                this.addtimes++;
            } finally {
                writeLock.unlock();
            }
        }
        public String getInfo() {
            Lock readLock = lock.readLock();
            readLock.lock();
            System.out.println("ReadWriteLockTest to getInfo   "
                    + System.currentTimeMillis());
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
            }
            try {
                return this.value + " : " + this.addtimes;
            } finally {
                readLock.unlock();
            }
        }
    }

    public static void testReadWriteLockTest() throws Exception{
        final ReadWriteLockTest readWriteLockTest = new ReadWriteLockTest();
        Runnable task_1 = new Runnable(){
            public void run(){
                readWriteLockTest.addValue(55.55);
            }
        };
        Runnable task_2 = new Runnable(){
            public void run(){
                System.out.println("info: " + readWriteLockTest.getInfo());
            }
        };
        ExecutorService cachedService_1 = Executors.newCachedThreadPool();
        Future future_1 = null;
        for (int i=0; i<2; i++){
            future_1 = cachedService_1.submit(task_1);
        }
        for (int i=0; i<2; i++){
            future_1 = cachedService_1.submit(task_2);
        }
        future_1 = cachedService_1.submit(task_1);

        future_1.get();
        cachedService_1.shutdownNow();
    }

    public static void main(String[] args) throws Exception{
        Lockers.testLockTest();
        System.out.println("---------------------");
        Lockers.testReadWriteLockTest();
    }
}
 

Java多線程編程中的lock使用源碼詳解