我想在登录窗口的用户名中输入数据时登录按钮为启用状态，用户名中无数据时登录按钮为未启用状态，我说的不是在用户名中输入数据为按回车才后登录才为启用状态，是在用户名中输入数据时为启用状态
各位大神千万别因为结帖率的问题就不指点啊 ，我的帖子就两个没有结帖，一个是昨天发的，还有一个就是现在这个啊
代码如下：
- Java code
/** * @(#)Login.java * * * @author * @version 1.00 2012/3/17 */ import java.awt.*; import javax.swing.*; import java.awt.event.*; import java.sql.*; import java.sql.Connection; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; class FrameTest extends JFrame { public FrameTest() { super("请登录"); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); setVisible(true); setSize(320, 240); } } class PanelTest extends FrameTest { JPanel panelObj; public PanelTest() { panelObj = new JPanel(); getContentPane().add(panelObj); } } class ComponentTest extends PanelTest { JLabel loginName; JLabel loginPassword; JTextField textName; JPasswordField textPassword; JButton buttonLogin; JButton buttonReset; public ComponentTest() { loginName = new JLabel("用户名："); loginPassword = new JLabel("密码："); buttonLogin = new JButton("登录"); buttonReset = new JButton("重置"); textName = new JTextField(10); textPassword = new JPasswordField(10); panelObj.add(loginName); panelObj.add(textName); panelObj.add(loginPassword); panelObj.add(textPassword); panelObj.add(buttonLogin); panelObj.add(buttonReset); } } public class Login extends ComponentTest { GridBagLayout gbLayoutObj; GridBagConstraints gbcObj; boolean b = false; public Login() { gbLayoutObj = new GridBagLayout(); gbcObj = new GridBagConstraints(); panelObj.setLayout(gbLayoutObj); gbcObj.anchor = GridBagConstraints.EAST; gbcObj.gridx = 1; gbcObj.gridy = 1; gbLayoutObj.setConstraints(loginName,gbcObj); gbcObj.gridy = 2; gbLayoutObj.setConstraints(loginPassword,gbcObj); gbcObj.anchor = GridBagConstraints.WEST; gbcObj.gridx = 2; gbcObj.gridy = 1; gbLayoutObj.setConstraints(textName,gbcObj); gbcObj.gridy = 2; gbLayoutObj.setConstraints(textPassword,gbcObj); gbcObj.anchor = GridBagConstraints.SOUTH; gbcObj.gridx = 1; gbcObj.gridy = 3; gbLayoutObj.setConstraints(buttonLogin,gbcObj); gbcObj.gridx = 2; gbLayoutObj.setConstraints(buttonReset,gbcObj); buttonLogin.setEnabled(true); buttonReset.addActionListener ( new ActionListener() { public void actionPerformed(ActionEvent e) { Login.this.Reset(); } } ); //textName.addActionListener(this); buttonLogin.addActionListener ( new ActionListener() { public void actionPerformed(ActionEvent e) { Login.this.f(); } } ); } protected void Reset() { textName.setText(""); textPassword.setText(""); } /* public void keyPressed(KeyEvent e) { buttonLogin.setEnabled(true); } public void keyReleased(KeyEvent e) { } public void keyTyped(KeyEvent e) { }*/ protected boolean f() { String url = "jdbc:odbc:driver={Microsoft Access Driver (*.mdb)};DBQ=J://course/AddressBook/Test/DataBase/Login.mdb"; try { Class.forName("sun.jdbc.odbc.JdbcOdbcDriver"); Connection con = DriverManager.getConnection(url); Statement st = con.createStatement(); String name = textName.getText().trim(); String pwd = textPassword.getText().trim(); ResultSet rs = st.executeQuery("select * from LoginMessage where ID = '" + name + "'"); if(rs.next()) { rs.close(); rs = st.executeQuery("select * from LoginMessage where ID = '" + name + "' and Pwd = '" + pwd + "'"); if(rs.next()) { JOptionPane.showMessageDialog(new JPanel(), "恭喜！！！登录成功"); setVisible(false); TestFrame frame = new TestFrame(); // Show frame. frame.show(true); } else { JOptionPane.showMessageDialog(new JPanel(), "密码输入错误！请确认后再次输入"); } } else { JOptionPane.showMessageDialog(new JPanel(), "用户名不存在"); } } catch(Exception ex) { ex.printStackTrace(); } return b; } }/*class LoginData { public boolean f () { String url = "jdbc:odbc:driver={Microsoft Access Driver (*.mdb)};DBQ=J://course/AddressBook/Test/DataBase/Login.mdb"; boolean bz = false; try { Class.forName("sun.jdbc.odbc.JdbcOdbcDriver"); Connection con = DriverManager.getConnection(url); Statement st = con.createStatement(); ResultSet rs = st.executeQuery("select * from LoginMessage where ID = " + textName.getText() + "and Pwd = " + textPassword.getText()); while(rs.next()) { bz = true; rs.close(); st.close(); con.close(); } } catch(Exception ex) { ex.printStackTrace(); } return bz; }}*/