Java怎么利用多线程模拟银行系统存钱问题

多线程6（模拟银行系统存钱）

1.题目

模拟一个简单的银行系统，使用两个不同的线程向同一个账户存钱。

实现：使用synchronized关键字，将存钱的方法修改成同步的。

2.解题思路

创建一个类：SynchronizedBankFrame，继承JFrame类

写一个内部类Bank

• 定义一个account变量，来表示账户。

• deposit():一个存钱的方法

• getAccount()：显示账户余额的方法。

写一个内部类Transfer，实现Runnable接口

在run方法中实现向账户存钱的功能。

同步方法就是用synchronized关键字修饰的方法。

JDK为每个JAVA对象配置了内置锁，如果方法使用synchronized关键字修饰,内置锁就会保护整个方法。

3.代码详解

SynchronizedBankFrame

package com.xiaoxuzhu;
import java.awt.BorderLayout;
import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JButton;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.GridLayout;
import javax.swing.JLabel;
import javax.swing.SwingConstants;
import java.awt.Font;
import javax.swing.UIManager;
/**
 * Description:
 *
 * @author xiaoxuzhu
 * @version 1.0
 *
 * <pre class="brush:php;toolbar:false">
 * 修改记录:
 * 修改后版本	        修改人		修改日期			修改内容
 * 2022/5/14.1	    xiaoxuzhu		2022/5/14		    Create
 * 

* @date 2022/5/14 */ public class SynchronizedBankFrame extends JFrame { /** * */ private static final long serialVersionUID = 2671056183299397274L; private JPanel contentPane; private JTextArea thread1TextArea; private JTextArea thread2TextArea; /** * Launch the application. */ public static void main(String[] args) { try { UIManager.setLookAndFeel("com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel"); } catch (Throwable e) { e.printStackTrace(); } EventQueue.invokeLater(new Runnable() { public void run() { try { SynchronizedBankFrame frame = new SynchronizedBankFrame(); frame.setVisible(true); } catch (Exception e) { e.printStackTrace(); } } }); } /** * Create the frame. */ public SynchronizedBankFrame() { setTitle("使用Synchronized实现线程同步"); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); setBounds(100, 100, 450, 300); contentPane = new JPanel(); contentPane.setBorder(new EmptyBorder(5, 5, 5, 5)); setContentPane(contentPane); contentPane.setLayout(new BorderLayout(0, 0)); JPanel buttonPanel = new JPanel(); contentPane.add(buttonPanel, BorderLayout.SOUTH); JButton startButton = new JButton("开始存钱"); startButton.setFont(new Font("微软雅黑", Font.PLAIN, 16)); startButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent arg0) { do_button_actionPerformed(arg0); } }); buttonPanel.add(startButton); JPanel processPanel = new JPanel(); contentPane.add(processPanel, BorderLayout.CENTER); processPanel.setLayout(new GridLayout(1, 2, 5, 5)); JPanel thread1Panel = new JPanel(); processPanel.add(thread1Panel); thread1Panel.setLayout(new BorderLayout(0, 0)); JLabel thread1Label = new JLabel("一号线程"); thread1Label.setFont(new Font("微软雅黑", Font.PLAIN, 16)); thread1Label.setHorizontalAlignment(SwingConstants.CENTER); thread1Panel.add(thread1Label, BorderLayout.NORTH); JScrollPane thread1ScrollPane = new JScrollPane(); thread1Panel.add(thread1ScrollPane, BorderLayout.CENTER); thread1TextArea = new JTextArea(); thread1TextArea.setFont(new Font("微软雅黑", Font.PLAIN, 16)); thread1ScrollPane.setViewportView(thread1TextArea); JPanel thread2Panel = new JPanel(); processPanel.add(thread2Panel); thread2Panel.setLayout(new BorderLayout(0, 0)); JLabel thread2Label = new JLabel("二号线程"); thread2Label.setFont(new Font("微软雅黑", Font.PLAIN, 16)); thread2Label.setHorizontalAlignment(SwingConstants.CENTER); thread2Panel.add(thread2Label, BorderLayout.NORTH); JScrollPane thread2ScrollPane = new JScrollPane(); thread2Panel.add(thread2ScrollPane, BorderLayout.CENTER); thread2TextArea = new JTextArea(); thread2TextArea.setFont(new Font("微软雅黑", Font.PLAIN, 16)); thread2ScrollPane.setViewportView(thread2TextArea); } protected void do_button_actionPerformed(ActionEvent arg0) { Bank bank = new Bank(); Thread thread1 = new Thread(new Transfer(bank, thread1TextArea)); thread1.start(); Thread thread2 = new Thread(new Transfer(bank, thread2TextArea)); thread2.start(); } private class Transfer implements Runnable { private Bank bank; private JTextArea textArea; public Transfer(Bank bank, JTextArea textArea) {// 初始化变量 this.bank = bank; this.textArea = textArea; } public void run() { for (int i = 0; i < 10; i++) {// 向账户中存入10次钱 bank.deposit(10);// 向账户中存入10块钱 String text = textArea.getText();// 获得文本域中的文本 // 在文本域中显示账户中的余额 textArea.setText(text + "账户的余额是：" + bank.getAccount() + "\n"); } } } private class Bank { private int account = 100;// 每个账户的初始金额是100元 public synchronized void deposit(int money) {// 向账户中存入money元 account += money; } public int getAccount() {// 查询账户余额 return account; } } }

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