关于java多线程任务执行时共享资源加锁的方式思考

1.加锁方式:

  1-1.使用synchronized关键字进行方法或代码块的加锁方式

  1-2.使用ReentrantLock类提供的lock()方法的方式

2.代码实现(传统的银行取款存款问题):

  2-1.Account.java类:账户类

package com.java.thread;

import java.util.concurrent.locks.ReentrantLock;
/**
 * 账户类
 * @author steven
 *
 */
public class Account {

    public double money = 6000;
    public ReentrantLock lock = new ReentrantLock();
    public Account(double money){
        this.money = money;
    }
    public void drawmoney(double money,String name){
        synchronized (this) {
            this.money -= money;
            System.out.println(name+"取款后剩余钱数:"+this.money);
        }
    }
    
    public void drawmoney1(double money,String name){
        lock.lock();
        try {
            this.money -= money;
            System.out.println(name+"取款后剩余钱数:"+this.money);
        }catch (Exception e) {
            // TODO: handle exception
        }finally{
            lock.unlock();
        }
    }
    
    public synchronized void cunmony(double money,String name){
            this.money += money;
            System.out.println(name+"存款后剩余钱数:"+this.money);
    }
    
}
View Code

  2-2.User.java类:线程实现类

package com.java.thread;

/**
 * 继承线程类,重写run方法
 * @author steven
 *
 */
public class User extends Thread{

    private String username;
    private Account account;
    public User(String username,Account account){
        this.username = username;
        this.account = account;
    }
    public void run(){
        if (username.contains("0")||username.contains("1")||username.contains("2"))
            this.account.cunmony(1000,username);
        else if(username.contains("3"))
            this.account.drawmoney(500, username);
        else
            this.account.drawmoney1(100, username);
    }
    public static void main(String[] args) {
        Account account = new Account(10000);
        User user = null;
        for (int i = 0; i < 5; i++) {
            user = new User("user"+i, account);
            user.setPriority(i+1);
            user.start();
        }
    }
}
View Code

3.误区总结:

  账户在这一问题中就算是多线程问题中的共享资源,在线程实现类中,我们需要使用构造函数的方式将该资源定义到该类的构造函数里,在具体多线程操作时创建唯一的资源,并将其放入新建线程的构造函数中,这样就能实现模拟多个线程操作同一资源的效果。

posted @ 2018-11-05 15:22  海的味道  阅读(1810)  评论(0编辑  收藏  举报