标签：current catch 异步 void 任务 总结 org try ade
ReentrantLock具有完全互斥排他的效果，即同一时间只有一个线程在执行ReentrantLock.lock()方法后面的任务。这样做虽然保证了实例变量的线程安全，但效率却是非常低下的。JDK中提供了一个读写锁ReentrantReadWriteLock，使用它可以加快运行效率，在某些不需要操作实例变量的方法中，完全可以使用读写锁ReentrantReadWriteLock来提升该方法的代码运行速度。
读写锁有两个锁：读锁和写锁，读锁也称为共享锁，写锁称为排他锁。也就是多个读锁之间不互斥，读锁与写锁互斥，写锁与写锁互斥。
package org.github.lujiango;
import java.util.concurrent.locks.ReentrantReadWriteLock;
public class Test09 {
static class Service {
private ReentrantReadWriteLock lock = new ReentrantReadWriteLock();
public void read() {
try {
lock.readLock().lock();
System.out.println("get read lock: " + Thread.currentThread().getName());
Thread.sleep(10000);
} catch (Exception e) {
e.printStackTrace();
} finally {
lock.readLock().unlock();
}
}
public void write() {
try {
lock.writeLock().lock();
System.out.println("get write lock: " + Thread.currentThread().getName());
Thread.sleep(10000);
} catch (Exception e) {
e.printStackTrace();
} finally {
lock.writeLock().unlock();
}
}
}
static class ThreadReader extends Thread {
private Service service;
public ThreadReader(Service service) {
this.service = service;
}
@Override
public void run() {
service.read();
}
}
static class ThreadWriter extends Thread {
private Service service;
public ThreadWriter(Service service) {
this.service = service;
}
@Override
public void run() {
service.write();
}
}
public static void main(String[] args) {
Service service = new Service();
// (1) 读读
ThreadReader r1 = new ThreadReader(service);
ThreadReader r2 = new ThreadReader(service);
r1.start();
r2.start();
// (2) 写写
ThreadWriter w1 = new ThreadWriter(service);
ThreadWriter w2 = new ThreadWriter(service);
w1.start();
w2.start();
}
}
总结：读写，写读，写写都是互斥的；而读读是异步的，非互斥的。
标签：current catch 异步 void 任务 总结 org try ade
原文地址：http://www.cnblogs.com/lujiango/p/7581001.html
