1.项目功能展示

2.新建一个以Maven为系统的的项目

此项目是将用户的所有信息存放在本地JSON文件中，所以我们需要解析JSON数据，本项目使用的是google的Gson,我们需要在项目的配置文件pom.xml中写入以下代码：

 <dependencies>
        <dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
            <version>2.8.2</version>
        </dependency>
    </dependencies>

我们需要解析时，只要导入Gson即可，可以根据需求按需导入

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.reflect.TypeToken;

3.创建User类以及Login类以及Register类

(1)首先我们先创建一个User的JavaBean，包括id,username以及password

public class User {
    private String id;
    private String username;
    private String password;

    public User(String id, String username, String password) {
        this.id = id;
        this.username = username;
        this.password = password;
    }

    public User() {
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }
}

(2)创建Login类以及利用Swing实现GUI图形设计并实现读取Json数据与用户输入信息进行校验

import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.FileReader;
import java.util.ArrayList;

public class Login extends JFrame implements ActionListener {

    private JTextField usernameText;
    private JPasswordField passwordText;
    private JButton loginBtn;
    private JButton registerBtn;

    public Login() {
        setTitle("登录");
        setAlwaysOnTop(true);
        setLayout(null);//关闭默认布局类型 自己手动设置布局
        setSize(400, 400);
        setDefaultCloseOperation(3);//设置关闭模式
        setLocationRelativeTo(null);//设置GUI显示居中
        //创建界面组件
        JLabel username = new JLabel("账号：");
        JLabel password = new JLabel("密码：");
        loginBtn = new JButton("登录");
        loginBtn.addActionListener(this);//监听登录事件
        registerBtn = new JButton("注册");
        registerBtn.addActionListener(this);//监听注册事件
        usernameText = new JTextField(15);
        passwordText = new JPasswordField(15);
        // 设置字体和背景颜色
        usernameText.setForeground(Color.BLACK);
        passwordText.setForeground(Color.BLACK);
        usernameText.setBorder(BorderFactory.createLineBorder(Color.GRAY));
        passwordText.setBorder(BorderFactory.createLineBorder(Color.GRAY));
        //创建装组件的容器
        JPanel usernameJp = new JPanel();
        JPanel passwordJp = new JPanel();
        JPanel loginJp = new JPanel();
        //设置容器的位置
        usernameJp.setBounds(30, 0, 300, 50);
        passwordJp.setBounds(30, 40, 300, 50);
        loginJp.setBounds(30, 90, 300, 60);
        usernameJp.add(username);
        usernameJp.add(usernameText);
        passwordJp.add(password);
        passwordJp.add(passwordText);
        loginJp.add(loginBtn);
        loginJp.add(registerBtn);
        //将组件装入GUI
        add(usernameJp);
        add(passwordJp);
        add(loginJp);
        setVisible(true);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == loginBtn) {
            String username = usernameText.getText();
            String password = new String(passwordText.getPassword());
            // 根据读取的用户账号信息进行校验
            boolean temp = readUser(username, password);
            System.out.println(temp);
            if (temp) {
                JOptionPane.showMessageDialog(this, "登录成功", "Success", JOptionPane.INFORMATION_MESSAGE);
                this.dispose();//登录成功关闭此窗口 跳转页面
            } else {
                JOptionPane.showMessageDialog(this, "登陆失败", "Error", JOptionPane.ERROR_MESSAGE);
            }
        }//注册操作
        else {
            this.dispose();
            new Register();
        }
    }

    //读取用户数据
    public boolean readUser(String username, String password) {

        try (BufferedReader br = new BufferedReader(new FileReader("Json文件的相对路径或绝对路径"))) {
            String json = "";
            String line;
            while ((line = br.readLine()) != null) {
                json += line + "\n";
            }
            Gson gson = new Gson();
            ArrayList<User> dataList = gson.fromJson(json, new TypeToken<ArrayList<User>>() {
            }.getType());
            for (User data : dataList) {
                if (data.getUsername().equals(username) && data.getPassword().equals(password)) {
                    return true;
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return false;
    }

}

此时的运行图为：

等我们点击登录就会校验用户输入的账号和密码，若点击注册则会关闭当前的窗口，跳转到注册的窗口。

(3)创建Register类以及利用Swing实现GUI图形设计并实现创建用户更新Json数据

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.reflect.TypeToken;

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.*;
import java.util.ArrayList;

public class Register extends JFrame implements ActionListener {

    private JTextField usernameText;
    private JPasswordField passwordText;
    private JPasswordField passwordTextTrue;
    private JButton registerBtn;

    public Register() {
        setLayout(null);
        setTitle("注册");
        setSize(400, 400);
        setAlwaysOnTop(true);//设置界面一直处于最上层
        setDefaultCloseOperation(3);
        setLocationRelativeTo(null);
        //组件
        JLabel username = new JLabel("账号：");
        JLabel password = new JLabel("密码：");
        JLabel passwordTrue = new JLabel("确认密码：");
        registerBtn = new JButton("注册");
        registerBtn.addActionListener(this);
        usernameText = new JTextField(15);
        passwordText = new JPasswordField(15);
        passwordTextTrue = new JPasswordField(15);
        // 设置字体和背景颜色
        usernameText.setForeground(Color.BLACK);
        passwordText.setForeground(Color.BLACK);
        passwordTextTrue.setForeground(Color.BLACK);
        usernameText.setBorder(BorderFactory.createLineBorder(Color.GRAY));
        passwordText.setBorder(BorderFactory.createLineBorder(Color.GRAY));
        passwordTextTrue.setBorder(BorderFactory.createLineBorder(Color.GRAY));
        //创建装组件的容器
        JPanel usernameJp = new JPanel();
        JPanel passwordJp = new JPanel();
        JPanel passwordTrueJp = new JPanel();
        JPanel registerJp = new JPanel();
        //设置容器的位置
        usernameJp.setBounds(30, 0, 300, 40);
        passwordJp.setBounds(30, 50, 300, 40);
        passwordTrueJp.setBounds(18, 100, 300, 40);
        registerJp.setBounds(60, 140, 300, 50);

        usernameJp.add(username);
        usernameJp.add(usernameText);
        passwordJp.add(password);
        passwordJp.add(passwordText);
        passwordTrueJp.add(passwordTrue);
        passwordTrueJp.add(passwordTextTrue);
        registerJp.add(registerBtn);
        //将组件装入GUI
        add(usernameJp);
        add(passwordJp);
        add(passwordTrueJp);
        add(registerJp);
        setVisible(true);
        setVisible(true);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        String username = usernameText.getText();
        String password = new String(passwordText.getPassword());
        String passwordTrue = new String(passwordTextTrue.getPassword());
        ArrayList<User> user = getUserList();
        for (User data : user) {
            System.out.println(data.getUsername());
        }
        boolean found = false;
        found = (!username.equals("") && !password.equals("") && !passwordTrue.equals("") && password.equals(passwordTrue));
        System.out.println(found);
        if (found) {
            boolean temp = readUser(username, user);//检测用户名是否重复
            if (temp) {
                JOptionPane.showMessageDialog(this, "注册成功", "Success", JOptionPane.INFORMATION_MESSAGE);
                String id = "00" + (user.toArray().length + 1);
                user.add(new User(id, username, password));
                writeUser(username, password, user);//将新用户的数据写入json表中
                this.dispose();
                new Login();
            } else {
                JOptionPane.showMessageDialog(this, "用户名重复，注册失败", "Error", JOptionPane.ERROR_MESSAGE);
            }
        } else {
            JOptionPane.showMessageDialog(this, "注册失败,请正确填写用户名和密码", "Error", JOptionPane.ERROR_MESSAGE);
        }
    }

    //获取用户的所有信息数据
    public ArrayList<User> getUserList() {
        try (BufferedReader br = new BufferedReader(new FileReader("json文件的路径"))) {
            String json = "";
            String line;
            while ((line = br.readLine()) != null) {
                json += line + "\n";
            }
            Gson gson = new Gson();
            ArrayList<User> dataList = gson.fromJson(json, new TypeToken<ArrayList<User>>() {
            }.getType());
            return dataList;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return new ArrayList<User>();
    }

    //读取用户数据 检查有没有出现用户名重复的情况
    public boolean readUser(String username, ArrayList<User> user) {
        for (User data : user) {
            if (data.getUsername().equals(username)) {
                return false;
            }
        }
        return true;
    }

    //将用户信息写入json文件中
    public void writeUser(String username, String password, ArrayList<User> user) {
        try (Writer writer = new FileWriter("json文件路径")) {
            Gson gson = new GsonBuilder().setPrettyPrinting().create();
            gson.toJson(user, writer);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

注册的运行图为：

此窗口的功能可以实现注册用户并更新json文件数据，还可以进行安全性检验，防止用户名出现重复的情况，当注册成功之后就会跳转到登录页面。

4.新建测试类以及Json数据

（1）我们可以随意新建一个测试类，然后在测试类中写入以下代码

public class Main {
    public static void main(String[] args) {
        new Login();
    }
}

（2）新建一个data.json文件

[
  {
    "id": "001",
    "username": "zs",
    "password": "123456"
  },
  {
    "id": "002",
    "username": "ls",
    "password": "123456"
  },
  {
    "id": "003",
    "username": "wu",
    "password": "123456"
  }
]

我们尝试登录，如果账号密码输入正确就会弹出成功的提示框，否则会弹出失败的提示框