可重入锁是什么？
可以防止死锁，是同一把锁
代码：
代码语言：javascript复制package com.javaliao.backstage;
class Phone{
public synchronized void sendSMS(){
System.out.println(Thread.currentThread().getName() "t 发短信");
sendEmail();
}
public synchronized void sendEmail(){
System.out.println(Thread.currentThread().getName() "t 发邮件");
}
}
public class Demo {
public static void main(String[] args) {
Phone phone = new Phone();
new Thread(()->{
phone.sendSMS();
},"t1").start();
new Thread(()->{
phone.sendSMS();
},"t2").start();
}
}控制台：
生活案例：
家里的大门有一把锁，厕所没有上锁。我进了大门了，就不用在厕所上锁了。
ReentrantLock就是把可重入锁
代码语言：javascript复制package com.javaliao.backstage;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
class Phone implements Runnable{
Lock lock = new ReentrantLock();
@Override
public void run() {
sendSMS();
}
public void sendSMS(){
//加几把就要解锁几次
lock.lock();
lock.lock();
try {
System.out.println(Thread.currentThread().getName() "t 发短信");
sendEmail();
} finally {
lock.unlock();
lock.unlock();
}
}
public void sendEmail(){
lock.lock();
try {
System.out.println(Thread.currentThread().getName() "t 发邮件");
} finally {
lock.unlock();
}
}
}
public class Demo {
public static void main(String[] args) {
Phone phone = new Phone();
Thread t1 = new Thread(phone,"t1");
Thread t2 = new Thread(phone,"t2");
t1.start();
t2.start();
}
}
