java多线程快速入门（十八）

Posted 2021-01-22 cppdy

Lock锁是JDK1.5之后推出的并发包里面的关键字（注意捕获异常，释放锁）

Lock与synchronized的区别

　　Lock锁可以人为的释放锁（相当于汽车中的手动挡）

　　synchronized当线程执行完毕或者抛出异常的话，锁自动释放（相当于汽车中的自动挡）

Condition用法

　　Condition的功能类似于在传统的线程技术中的Object.wait()和Object.notify()的功能

package com.cppdy;

import java.util.concurrent.locks.Condition;
//JDK1.5之后出现的并发包
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

class User1 {

    public String username;
    public String sex;
    // 如果flag为false 证明变量可写不可读
    // 如果flag为true 证明变量可读不可写
    public boolean flag = false;

    public Lock lock = new ReentrantLock();

}

class InputThread1 extends Thread {
    private User1 user;
    private Condition condition;
    
    public InputThread1(User1 user,Condition condition) {
        this.user = user;
        this.condition=condition;
    }

    @Override
    public void run() {
        int count = 0;
        while (true) {
            user.lock.lock();
            try {
                if (user.flag) {
                    condition.await();
                }
                if (count % 2 == 0) {
                    user.username = "cppdy";
                    user.sex = "nan";
                } else {
                    user.username = "吹泡泡的魚";
                    user.sex = "男";
                }
                count++;
                // 将user标记变为可读
                user.flag = true;
                condition.signal();
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                user.lock.unlock();
            }
        }
    }
}

class OutThread1 extends Thread {
    private User1 user;
    private Condition condition;

    public OutThread1(User1 user,Condition condition) {
        this.user = user;
        this.condition=condition;
    }

    @Override
    public void run() {
        while (true) {
            user.lock.lock();
            try {
                if (!user.flag) {
                    condition.await();
                }
                System.out.println(user.username + "--" + user.sex);
                // 将user标记变为可写
                user.flag = false;
                condition.signal();
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                user.lock.unlock();
            }
        }
    }
}

public class ThreadDemo14 {

    public static void main(String[] args) throws Exception {
        User1 user = new User1();
        Condition condition=user.lock.newCondition();
        InputThread1 it = new InputThread1(user,condition);
        OutThread1 ot = new OutThread1(user,condition);
        it.start();
        ot.start();
    }

}