用javaSwing和mysql数据库做的一个登录页面

一：首先在eclipse中新建一个java工程

二：然后新建一个包，并且在包中新建两个类：一个事登录用的界面(Login)类，一个事连接数据库的（jdbc）类我建立的是p4这个包

三：导入包mysql-connector-java-5.1.41-bin.jar并且要添加到构建路径不添加到构建路径项目工程不会读出来的

四：编写那个界面Login类

那个界面类的源代码如下：

package p4;

import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JPasswordField;
import javax.swing.JTextField;

public class Login extends JFrame implements ActionListener {
private JPanel pan = new JPanel();
private JLabel namelab = new JLabel("用户名");
private JLabel passlab = new JLabel("密    码");
private JTextField nametext = new JTextField();
private JPasswordField passtext = new JPasswordField();

public JButton denglu = new JButton("登录");
public JButton zhuce = new JButton("注册");
public JButton updatepass = new JButton("修改密码");
public JButton deleteuser = new JButton("删除用户");

public Login(){
	Font font = new Font("宋体",Font.BOLD,12);
	super.setTitle("欢迎登录本系统");
	pan.setLayout(null);
	namelab.setBounds(20,20,60,30);
	nametext.setBounds(90,20,140,30);
	passlab.setBounds(20,60,60,30);
	passtext.setBounds(90,60,140,30);
	denglu.setBounds(30,120,90,20);
	zhuce.setBounds(140,120,90,20);
	updatepass.setBounds(30,150,90,20);
	deleteuser.setBounds(140,150,90,20);
	
	pan.add(namelab);
	pan.add(nametext);
	pan.add(passlab);
	pan.add(passtext);
	pan.add(denglu);
	pan.add(zhuce);
	pan.add(updatepass);
	pan.add(deleteuser);
	
	passtext.setFont(font);
	zhuce.setFont(font);
	updatepass.setFont(font);
	deleteuser.setFont(font);
	
	denglu.addActionListener(this);
	zhuce.addActionListener(this);
	updatepass.addActionListener(this);
	deleteuser.addActionListener(this);
	
	super.add(pan);
	super.setSize(300,250);
	super.setVisible(true);
}

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

	@Override
	public void actionPerformed(ActionEvent arg0) {
	if(arg0.getSource()==denglu){
		denglu();
	}else if (arg0.getSource()==zhuce){
		zhuce();
	}else if (arg0.getSource()==updatepass){
		updatepass();
	}else if (arg0.getSource()==deleteuser){
		deleteuser();
	}

	}
	//登录按钮的事件处理函数
	public void denglu(){
	 Jdbcs d  =	new Jdbcs();
	 String username = nametext.getText();
	 String password = passtext.getText();
      if(d.compare(username, password)){
    	aJOptionPane.showMessageDialog(null,"登录成功！");
    	  super.setVisible(false);
      }
	}
	//注册按钮触发后的事件处理函数
	public void zhuce(){
		Jdbcs d  =	new Jdbcs();
		String username = nametext.getText();
		 String password = passtext.getText();
		 d.insert(username,password);
	}
	//修改密码按钮触发后的事件处理函数
	public void updatepass(){
		pan.setEnabled(false);
		JFrame frame1 = new JFrame("密码修改");
		frame1.setSize(250, 200);
		JPanel updatepass = new JPanel();
		JLabel namelab1 = new JLabel("用户名");
		JLabel passlab1 = new JLabel("旧密码");
		JLabel newpasslab = new JLabel("新密码");
		JTextField nametext1  = new JTextField(""+nametext.getText());
		JPasswordField passtext1 = new JPasswordField();
		JPasswordField newpasstext  = new JPasswordField();
		JButton ok = new JButton("修改");
		JButton resert = new JButton("重置");
		
		updatepass.setLayout(null);
		
		namelab1.setBounds(5,5,70,20);
		nametext1.setBounds(80,5,120,20);
		passlab1.setBounds(5,30,70,20);
		passtext1.setBounds(80,30,120,20);
		newpasslab.setBounds(5,60,70,20);
		newpasstext.setBounds(80,60,120,20);
		ok.setBounds(10,110,60,20);
		resert.setBounds(90,110,60,20);
		
		updatepass.add(namelab1);
		updatepass.add(nametext1);
		updatepass.add(passlab1);
		updatepass.add(passtext1);
		updatepass.add(newpasslab);
		updatepass.add(newpasstext);
		updatepass.add(ok);
		updatepass.add(resert);
		
		frame1.add(updatepass);
		frame1.setVisible(true);
		
		ok.addActionListener(new ActionListener(){

			@Override
			public void actionPerformed(ActionEvent arg0) {
				Jdbcs d  =	new Jdbcs();
				String username = nametext1.getText();
				 String password1 = passtext1.getText();
				 String newpassword = newpasstext.getText();
				if(d.update(username,password1,newpassword)){
					frame1.setVisible(false);
				}
			}
		});
		//重置文本框 里的内容
		resert.addActionListener(new ActionListener(){
			@Override
			public void actionPerformed(ActionEvent arg0) {
				
				nametext1.setText("");
				passtext1.setText("");
				newpasstext.setText("");
			}
		});
	}
	//删除用户按钮触发后的事件处理函数
	public void deleteuser(){
	String username = nametext.getText();
	String password = passtext.getText();
	Jdbcs s = new Jdbcs();
		s.delete(username,password);
	}

}

五：写连接数据库的代码以及用到的操作的源代码

jdbc这个类的源代码如下：

package p4;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import javax.swing.JOptionPane;

public class Jdbc {
Connection con = null;
Statement statement = null;
ResultSet res = null;
String driver = "com.mysql.jdbc.Driver";
String url  = "jdbc:mysql://localhost:3306/user";
String name = "root";
String passwd = "123456";

public Jdbc(){
	try{
	Class.forName(driver).newInstance();
	con = DriverManager.getConnection(url,name,passwd);
	statement = con.createStatement();
	
	}catch(ClassNotFoundException e){
		System.out.println("对不起，找不到这个Driver");
		e.printStackTrace();
	}catch(SQLException e){
		e.printStackTrace();
	}catch(Exception e){
		e.printStackTrace();
		}
}
//对用户信息的修改实际上就是对密码的修改
public boolean update(String username1,String password1,String newpassword){
	boolean judge = false;
	boolean s =compare(username1,password1);
	if(s){
	String sql = "update user set password=\""+newpassword+"\"where username=\""+username1+"\"";
	try {
		int a = statement.executeUpdate(sql);
		if(a==1){
			JOptionPane.showMessageDialog(null,"密码修改成功！");
			judge = true;
		}
		con.close();
		statement.close();
	} catch (SQLException e) {
        JOptionPane.showMessageDialog(null, "用户不存在！");
		e.printStackTrace();
	}
	}
	else{
		 JOptionPane.showMessageDialog(null, "修改失败");
	}
	return judge;
}
//删除用户信息
public void delete(String username,String password){
	if(compare(username,password)){
		JOptionPane.showMessageDialog(null,"已经完成删除");
	}else{
		return;
	}
	String sql = "delete from user where username=\""+username+"\"";
	try{
		int a =  statement.executeUpdate(sql);
		con.close();
		statement.close();
	}catch(SQLException e){
		JOptionPane.showMessageDialog(null,"不存在该用户！");
		e.printStackTrace();
	}
	
}
//用户注册功能的实现，添加数据
public void insert(String username,String password){
	String sql = "insert into user(username,password) values(\""+username+"\",\""+password+"\")";
	try{
		int a = statement.executeUpdate(sql);
		con.close();
		statement.close();
		if(a==1){
			JOptionPane.showMessageDialog(null,"注册成功！");
		}
	}catch(SQLException e){
		JOptionPane.showMessageDialog(null, "对不起该用户名已经有了！");
		e.printStackTrace();
	}
}
//对比用户名和密码是不匹配
public boolean compare(String username,String password){
	boolean m = false;
	String sql = "select password from user where username=\""+username+"\"";
    try{
    	res = statement.executeQuery(sql);
    	if(res.next()){
    		String pa = res.getString(1);
    		System.out.println(pa+" " +password);
    		if(pa.equals(password)){
    			m = true;
    		}else {
    			JOptionPane.showMessageDialog(null, "密码错误！");
        	}
    	}else {
    		JOptionPane.showMessageDialog(null, "用户名不存在！");
    	}
    	res.close();
    	con.close();
		statement.close();
    	
    }catch(SQLException e){
    	e.printStackTrace();
    }
    return m;
}

}

六：代码写完了 但是数据库还没有建立吧，那就建立数据库吧

先建立一个数据库

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用到命令是

create database user;

然后新建一个表：

use user;

create table user(username varchar(20) primary key, password varchar(20));

现在表是空的，往表中添加几个数据：

insert into user(username,password) values("A",“123456”）,("B","asdfg");

七：系统界面如下：