程序8-9：
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.*;
public class JTextFieldDemo2 {
JFrame frame = new JFrame ("JTextField Demo2");
JLabel nameLabel = new JLabel("User Name");
JLabel pwLabel = new JLabel("Password");
JTextField nameField = new JTextField();
JPasswordField pwField = new JPasswordField();
JTextArea ta = new JTextArea(5,20);
public static void main(String args[]) {
JTextFieldDemo2 tfd2 = new JTextFieldDemo2();
tfd2.go();
}
public void go() {
UpperCaseDocument ucDocument = new UpperCaseDocument();
nameField.setDocument(ucDocument);
nameField.setForeground(Color.red);
nameField.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
String username = nameField.getText(); //获取文本域的内容
ta.append("\nUser Name,"+username); //显示在文本区中
}
});
pwField.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
char[] pw = pwField.getPassword(); //获取文本域的内容
String password = new String(pw);
ta.append("\nPassword,"+password);
}
});
JPanel labelPanel = new JPanel();
labelPanel.setLayout(new GridLayout(2,1));
labelPanel.add(nameLabel);
labelPanel.add(pwLabel);
JPanel fieldPanel = new JPanel();
fieldPanel.setLayout(new GridLayout(2,1));
fieldPanel.add(nameField);
fieldPanel.add(pwField);
JPanel northPanel = new JPanel();
northPanel.setLayout(new GridLayout(1,2));
northPanel.add(labelPanel);
northPanel.add(fieldPanel);
JScrollPane jsp = new JScrollPane(ta,
JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
Container cp = frame.getContentPane();
cp.add(northPanel,BorderLayout.NORTH);
cp.add(jsp,BorderLayout.CENTER);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setVisible(true);
}
}
//自定义的Document,当用户输入字符时,自动将小写字母装换为大写字母
class UpperCaseDocument extends PlainDocument {
public void insertString(int offset,
String string,AttributeSet attributeSet)
throws BadLocationException {
string = string.toUpperCase(); //转换为大写字符
super.insertString(offset,string,attributeSet);
}
}