代码如下

package com.jnzyjsxy.test;

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

public class login extends Frame implements ActionListener {

TextField txtName;

TextField txtPassword;

Label lblTitle,lblName,lblPassword;

Button btnSubmit;

Button btnReset;

JButton clearInfo=new JButton();

static //创建网格包布局对象

GridBagLayout girdBag=new GridBagLayout();

//创建网格包约束类变量

GridBagConstraints girdBagCon;

public login(){

super("登陆界面");

//lblTitle=new Label("请输入您的用户信息:");

lblName=new Label("用户名:");

txtName=new TextField(15);

txtName.setFont(new Font("Dialog", 0, 15));

lblPassword=new Label("密码:");

txtPassword=new TextField(15);

txtPassword.setFont(new Font("Dialog", 0, 15));

txtPassword.setEchoChar('*');

btnSubmit=new Button("提交");

btnReset=new Button("重置");

//lblName.setText("用户名");

lblName.setFont(new Font("Dialog", 0, 16));

girdBagCon=new GridBagConstraints();

girdBagCon.gridx=0;

girdBagCon.gridy=1;

//外部填充 4个参数 top,left,bottom,right

//既外部间距

girdBagCon.insets=new Insets(0, 10, 10, 1);

girdBag.setConstraints(lblName, girdBagCon);

this.add(lblName);

girdBagCon=new GridBagConstraints();

girdBagCon.gridx=1;

girdBagCon.gridy=1;

girdBagCon.insets=new Insets(0, 1, 10, 15);

girdBag.setConstraints(txtName, girdBagCon);

this.add(txtName);

//lblPassword.setText("");

lblPassword.setFont(new Font("Dialog", 0, 16));

girdBagCon=new GridBagConstraints();

girdBagCon.gridx=0;

girdBagCon.gridy=2;

//外部填充 4个参数 top,left,bottom,right

//既外部间距

girdBagCon.insets=new Insets(0, 15, 10, 1);

girdBag.setConstraints(lblPassword, girdBagCon);

this.add(lblPassword);

girdBagCon=new GridBagConstraints();

girdBagCon.gridx=1;

girdBagCon.gridy=2;

girdBagCon.insets=new Insets(0, 1, 10, 15);

girdBag.setConstraints(txtPassword, girdBagCon);

this.add(txtPassword);

//addInfo.setText("增加");

btnSubmit.setFont(new Font("Dialog", 0, 16));

girdBagCon=new GridBagConstraints();

girdBagCon.gridx=0;

girdBagCon.gridy=3;

girdBagCon.gridwidth=2;

girdBagCon.gridheight=1;

//外部填充 4个参数 top,left,bottom,right

//既外部间距

girdBagCon.insets=new Insets(10, 10, 10, 90);

girdBag.setConstraints(btnSubmit, girdBagCon);

this.add(btnSubmit);

//clearInfo.setText("清空");

btnReset.setFont(new Font("Dialog", 0, 16));

girdBagCon=new GridBagConstraints();

girdBagCon.gridx=1;

girdBagCon.gridy=3;

girdBagCon.gridwidth=2;

girdBagCon.gridheight=1;

//外部填充 4个参数 top,left,bottom,right

//既外部间距

girdBagCon.insets=new Insets(10, 10, 10, -30);

girdBag.setConstraints(btnReset, girdBagCon);

this.add(btnReset);

this.btnSubmit.addActionListener(this);

this.btnReset.addActionListener(this);

addWindowListener(new WindowAdapter(){

public void windowClosing(WindowEvent e) {

System.exit(0);

}

});

}

public void actionPerformed(ActionEvent e){

String s=e.getActionCommand();

if(s.equals("重置")){

clear();

}else if(s.equals("提交")){

submit();

}else if(e.getSource()==txtName){

txtPassword.requestFocus();

}else if(e.getSource()==txtPassword){

submit();

}

}

public void clear(){

txtName.setText("");

txtPassword.setText("");

txtName.requestFocus();

}

public void submit(){

String n=txtName.getText();

String paw=txtPassword.getText();

if(n.equals("admin") && paw.equals("123")){

JOptionPane.showMessageDialog(this,"合法用户，欢迎进入本系统");

HrP hrP=new HrP();

}else{

JOptionPane.showMessageDialog(this, "非法用户，禁止进入本系统");

System.exit(0);

}

}

public static void main(String[] args) {

try {

//UIManager--界面管理类

//外观设置成所使用的操作平台的外观

//即程序在哪个平台运行，显示的窗口，对话框将是哪个平台的外观

UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());

login ttf=new login();

ttf.setSize(300,200);

//获取屏幕大小

Dimension

screenSize=Toolkit.getDefaultToolkit().getScreenSize();

//获取当前项目的窗体大小

Dimension frameSize=ttf.getSize();

//如果项目窗体高>屏幕高，用屏幕高设置项目窗体高

if (frameSize.height>screenSize.height) {

frameSize.height=screenSize.height;

}

if (frameSize.width>screenSize.width) {

frameSize.width=screenSize.width;

}

ttf.setLocation((screenSize.width-frameSize.width)/2,

(screenSize.height-frameSize.height)/2);;

ttf.setLayout(girdBag);

ttf.setResizable(false);

ttf.setVisible(true);

} catch (Exception e) {

// TODO: handle exception

e.printStackTrace();

}

//创建主类对象测试项目

new login();

}

}

来源： 庞玉栋--- Java程序员、WEB前端，技术宅