一个登陆界面

一个登陆界面，我知道的界面设计有2种，一种为纯代码设计的，一种为GUI窗体设计的。本人认为用GUI窗体设计比较简单方便。本文以图书馆管理系统为例，介绍图书馆管理系统的登陆界面。先用GUI设计如图界面：生成代码自动如下：

/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package com.derun.iframe;

//import com.derun.dao.User;
//import com.derun.dao.UserDAO;
//import com.derun.xuejava.Library;
//import javax.swing.JOptionPane;

/**
*
* @author Administrator
*/
public class LoginJFrame extends javax.swing.JFrame {

/**
* Creates new form LoginJFrame
*/
public LoginJFrame() {
initComponents();
}

/**
* This method is called from within the constructor to initialize the form.
* WARNING: Do NOT modify this code. The content of this method is always
* regenerated by the Form Editor.
*/
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {

jPanel1 = new javax.swing.JPanel();
jLabel2 = new javax.swing.JLabel();
jLabel3 = new javax.swing.JLabel();
password = new javax.swing.JPasswordField();
username = new javax.swing.JTextField();
jLabel1 = new javax.swing.JLabel();
jPanel2 = new javax.swing.JPanel();
btn_login = new javax.swing.JButton();
btn_reset = new javax.swing.JButton();

setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

jPanel1.setPreferredSize(new java.awt.Dimension(279, 150));

jLabel2.setText("用户名：");

jLabel3.setText("密 码：");

username.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
usernameActionPerformed(evt);
}
});

jLabel1.setIcon(new javax.swing.ImageIcon(getClass().getResource("/Images/login.jpg"))); // NOI18N
jLabel1.setPreferredSize(new java.awt.Dimension(200, 60));

javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
jPanel1.setLayout(jPanel1Layout);
jPanel1Layout.setHorizontalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addGap(33, 33, 33)
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(jLabel2)
.addComponent(jLabel3))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(username, javax.swing.GroupLayout.DEFAULT_SIZE, 148, Short.MAX_VALUE)
.addComponent(password))
.addContainerGap())
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
.addGap(0, 0, Short.MAX_VALUE)
.addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 279, javax.swing.GroupLayout.PREFERRED_SIZE))
);
jPanel1Layout.setVerticalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 76, Short.MAX_VALUE)
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(username, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel2))
.addGap(18, 18, 18)
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel3)
.addComponent(password, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(44, 44, 44))
);

getContentPane().add(jPanel1, java.awt.BorderLayout.CENTER);

jPanel2.setPreferredSize(new java.awt.Dimension(277, 60));

btn_login.setText("登陆");
btn_login.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btn_loginActionPerformed(evt);
}
});

btn_reset.setText("重置");
btn_reset.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btn_resetActionPerformed(evt);
}
});

javax.swing.GroupLayout jPanel2Layout = new javax.swing.GroupLayout(jPanel2);
jPanel2.setLayout(jPanel2Layout);
jPanel2Layout.setHorizontalGroup(
jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel2Layout.createSequentialGroup()
.addContainerGap(68, Short.MAX_VALUE)
.addComponent(btn_login)
.addGap(42, 42, 42)
.addComponent(btn_reset)
.addGap(55, 55, 55))
);
jPanel2Layout.setVerticalGroup(
jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel2Layout.createSequentialGroup()
.addContainerGap()
.addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(btn_login)
.addComponent(btn_reset))
.addContainerGap(27, Short.MAX_VALUE))
);

getContentPane().add(jPanel2, java.awt.BorderLayout.PAGE_END);

pack();
}// </editor-fold>

/**
* @param args the command line arguments
*/
public static void main(String args[]) {
/* Set the Nimbus look and feel */
//<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
/* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
* For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html */
try {
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(LoginJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(LoginJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(LoginJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(LoginJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>

/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new LoginJFrame().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JButton btn_login;
private javax.swing.JButton btn_reset;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JLabel jLabel3;
private javax.swing.JPanel jPanel1;
private javax.swing.JPanel jPanel2;
private javax.swing.JPasswordField password;
private javax.swing.JTextField username;
// End of variables declaration
}

然后双击重置按钮：可以对此按钮进行编程：

private void btn_resetActionPerformed(java.awt.event.ActionEvent evt) {
//用户单击了“重置”按钮，则清空用户名和密码文本框
username.setText("");
password.setText("");
}

而对于登陆按钮 如果是普通的不用连接数据库的设计同样先双击“登陆”按钮出现编程代码地方：

private void btn_loginActionPerformed(java.awt.event.ActionEvent evt) {

String user_name = username.getText().trim();
String pass_word = new String(password.getPassword());

if ('admin'.equals(user_name)&&'123456'.equals(pass_word)) {Library ly = new Library();ly.setVisible(true);this.setVisible(false);}}              

如果是连接数据库，首先实现好数据库部分，然后可以用DAO作为连接实现。