package function.thread;
import java.util.Random;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
public class LockTest {
public static void main(String args[]){
final ShareResourceOper sro = new ShareResourceOper();
for (int i = 0; i < 3; i++) {
new Thread() {
public void run() {
while (true) {
sro.get();
}
}
}.start();//三个消费者
new Thread() {
public void run() {
while (true) {
sro.put(new Random().nextInt(10000));
}
}
}.start();//三个生产者
}
}
}
class ShareResourceOper {
private Object shareData = null;// 共享数据，只能有一个线程能写该数据，但可以有多个线程同时读该数据。
//读写锁
ReadWriteLock rwl = new ReentrantReadWriteLock();
// 相当于读操作
public void get() {
rwl.readLock().lock();
String threadName = Thread.currentThread().getName();
try {
System.out.println("**************** read thread "+threadName + " be ready to read data!");
Thread.sleep(1000);
if(this.shareData !=null && !this.shareData.equals("")){
System.out.println(" read thread "+threadName+ " have read data :" + shareData);
}else{
System.out.println(" read thread "+threadName+ " empty !");
}
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
System.out.println("**************** read thread "+threadName+ " release the lock !");
//可能执行完该语句，读线程就抢占了CPU,要想精准看出锁的同步排斥机制，system语句需要放在锁语句的前面
rwl.readLock().unlock();
//System.out.println("**************** read thread "+threadName+ " release the lock !");
}
}
// 相当于写操作
public void put(Object data) {
rwl.writeLock().lock();
String threadName = Thread.currentThread().getName();
try {
System.out.println("**************** write thread "+threadName+ " be ready to write data!");
Thread.sleep(1000);
this.shareData = data;
System.out.println(" write thread "+threadName+ " have write data: " + data);
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
System.out.println("**************** write thread "+threadName+ " release the lock !");
rwl.writeLock().unlock();
}
}
}
运行结果：
**************** read thread Thread-0 be ready to read data!
**************** read thread Thread-2 be ready to read data!
**************** read thread Thread-4 be ready to read data!
read thread Thread-0 empty !
**************** read thread Thread-0 release the lock !
read thread Thread-2 empty !
**************** read thread Thread-2 release the lock !
read thread Thread-4 empty !
**************** read thread Thread-4 release the lock !
**************** write thread Thread-3 be ready to write data!
write thread Thread-3 have write data: 692
**************** write thread Thread-3 release the lock !
**************** write thread Thread-3 be ready to write data!
write thread Thread-3 have write data: 349
**************** write thread Thread-3 release the lock !
**************** write thread Thread-1 be ready to write data!
write thread Thread-1 have write data: 6981
**************** write thread Thread-1 release the lock !
**************** write thread Thread-1 be ready to write data!
write thread Thread-1 have write data: 3742
**************** write thread Thread-1 release the lock !
**************** write thread Thread-1 be ready to write data!
write thread Thread-1 have write data: 2155
**************** write thread Thread-1 release the lock !
**************** write thread Thread-5 be ready to write data!
write thread Thread-5 have write data: 6080
**************** write thread Thread-5 release the lock !
**************** write thread Thread-5 be ready to write data!
write thread Thread-5 have write data: 1327
**************** write thread Thread-5 release the lock !
**************** write thread Thread-5 be ready to write data!
write thread Thread-5 have write data: 9358
**************** write thread Thread-5 release the lock !
**************** read thread Thread-0 be ready to read data!
**************** read thread Thread-2 be ready to read data!
**************** read thread Thread-4 be ready to read data!
read thread Thread-0 have read data :9358
**************** read thread Thread-0 release the lock !
read thread Thread-4 have read data :9358
**************** read thread Thread-4 release the lock !
read thread Thread-2 have read data :9358
**************** read thread Thread-2 release the lock !
**************** write thread Thread-3 be ready to write data!
write thread Thread-3 have write data: 3529
**************** write thread Thread-3 release the lock !
**************** write thread Thread-3 be ready to write data!
write thread Thread-3 have write data: 9146
**************** write thread Thread-3 release the lock !
**************** write thread Thread-1 be ready to write data!
write thread Thread-1 have write data: 1339
**************** write thread Thread-1 release the lock !
**************** write thread Thread-1 be ready to write data!
write thread Thread-1 have write data: 4327
**************** write thread Thread-1 release the lock !
**************** write thread Thread-5 be ready to write data!
write thread Thread-5 have write data: 2020
**************** write thread Thread-5 release the lock !
**************** read thread Thread-0 be ready to read data!
**************** read thread Thread-4 be ready to read data!
**************** read thread Thread-2 be ready to read data!
read thread Thread-0 have read data :2020
**************** read thread Thread-0 release the lock !
read thread Thread-4 have read data :2020
**************** read thread Thread-4 release the lock !
read thread Thread-2 have read data :2020
**************** read thread Thread-2 release the lock !
**************** write thread Thread-3 be ready to write data!
write thread Thread-3 have write data: 633
**************** write thread Thread-3 release the lock !
**************** write thread Thread-3 be ready to write data!
write thread Thread-3 have write data: 5760
**************** write thread Thread-3 release the lock !
**************** write thread Thread-3 be ready to write data!
write thread Thread-3 have write data: 2856
**************** write thread Thread-3 release the lock !
**************** write thread Thread-3 be ready to write data!
write thread Thread-3 have write data: 1045
**************** write thread Thread-3 release the lock !
**************** write thread Thread-1 be ready to write data!