Java线程同步

认识线程同步

 解决方案

方法一：同步代码块

package com.itheima.d3;

public class ThreadTest {
    public static void main(String[] args) {
        Accout acc = new Accout("ICBC-110",100000);
        new DrawThread(acc,"小明").start();//小明
        new DrawThread(acc,"小红").start();//小红

        Accout acc1 = new Accout("ICBC-112",100000);
        new DrawThread(acc,"小黑").start();//小黑
        new DrawThread(acc,"小白").start();//小白
    }
}

package com.itheima.d3;

public class Accout {
    private String cardId;
    private double money;

    public Accout() {
    }

    public Accout(String cardId, double money) {
        this.cardId = cardId;
        this.money = money;
    }

    public static void test(){
        synchronized (Accout.class){

        }
    }

    public void drawMoney(double money) {
        //是谁来取钱
        String name = Thread.currentThread().getName();
        //1、判断余额是否足够
        //this代表共享资源
        synchronized (this) {
            if (this.money >= money){
                System.out.println(name + "来取钱" + money + "成功");
                this.money -= money;
                System.out.println(name + "取钱后余额" + this.money);
            }else {
                System.out.println(name + "来取钱余额不足");
            }
        }
    }

    public String getCardId() {
        return cardId;
    }

    public void setCardId(String cardId) {
        this.cardId = cardId;
    }

    public double getMoney() {
        return money;
    }

    public void setMoney(double money) {
        this.money = money;
    }

}

package com.itheima.d3;

public class DrawThread extends Thread{
    private Accout acc;
    public DrawThread(Accout acc, String name){
        super(name);
        this.acc = acc;
    }

    @Override
    public void run() {
        //取钱(小明、小红)
        acc.drawMoney(100000);
    }
}

 

方法二：同步方

package com.itheima.d3;

public class ThreadTest {
    public static void main(String[] args) {
        Accout acc = new Accout("ICBC-110",100000);
        new DrawThread(acc,"小明").start();//小明
        new DrawThread(acc,"小红").start();//小红
    }
}

package com.itheima.d3;

public class Accout {
    private String cardId;
    private double money;

    public Accout() {
    }

    public Accout(String cardId, double money) {
        this.cardId = cardId;
        this.money = money;
    }


    //小明、小红同时来取钱
    //同步方法
    public synchronized void drawMoney(double money) {
        //是谁来取钱
        String name = Thread.currentThread().getName();
        //1、判断余额是否足够
        //this代表共享资源
        if (this.money >= money) {
            System.out.println(name + "来取钱" + money + "成功");
            this.money -= money;
            System.out.println(name + "取钱后余额" + this.money);
        } else {
            System.out.println(name + "来取钱余额不足");
        }
    }

    public String getCardId() {
        return cardId;
    }

    public void setCardId(String cardId) {
        this.cardId = cardId;
    }

    public double getMoney() {
        return money;
    }

    public void setMoney(double money) {
        this.money = money;
    }

}

package com.itheima.d3;

public class DrawThread extends Thread{
    private Accout acc;
    public DrawThread(Accout acc, String name){
        super(name);
        this.acc = acc;
    }

    @Override
    public void run() {
        //取钱(小明、小红)
        acc.drawMoney(100000);
    }
}

 

方法三：Lock锁

package com.itheima.d3;

public class DrawThread extends Thread{
    private Accout acc;
    public DrawThread(Accout acc, String name){
        super(name);
        this.acc = acc;
    }

    @Override
    public void run() {
        //取钱(小明、小红)
        acc.drawMoney(100000);
    }
}

package com.itheima.d3;

import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class Accout {
    private String cardId;
    private double money;
    //创建了一个对象
    private final Lock lk = new ReentrantLock();

    public Accout() {
    }

    public Accout(String cardId, double money) {
        this.cardId = cardId;
        this.money = money;
    }


    //小明、小红同时来取钱
    public  void drawMoney(double money) {
        //是谁来取钱
        String name = Thread.currentThread().getName();
        lk.lock();//加锁
        try {
            //1、判断余额是否足够
            if (this.money >= money) {
                System.out.println(name + "来取钱" + money + "成功");
                this.money -= money;
                System.out.println(name + "取钱后余额" + this.money);
            } else {
                System.out.println(name + "来取钱余额不足");
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            lk.unlock();//解锁
        }
    }

    public String getCardId() {
        return cardId;
    }

    public void setCardId(String cardId) {
        this.cardId = cardId;
    }

    public double getMoney() {
        return money;
    }

    public void setMoney(double money) {
        this.money = money;
    }

}

package com.itheima.d3;

public class ThreadTest {
    public static void main(String[] args) {
        Accout acc = new Accout("ICBC-110",100000);
        new DrawThread(acc,"小明").start();//小明
        new DrawThread(acc,"小红").start();//小红
    }
}