【求助】响应用户输入问题！

Question

我写了个登陆的对话框，想要输入用户名和密码后，连接指定的数据库。可在实现keyListener()接口的时候出现点问题。我是这样写的：package Test;import javax.swing.*;
import java.awt.*;
import java.awt.event.*;public class Logon extends JFrame implements ActionListener,KeyListener{  JLabel usernameLabel = new JLabel("Username :",JLabel.LEFT);
  JTextField username = new JTextField(20);
  JLabel passwordLabel = new JLabel("Password :",JLabel.LEFT);
  JPasswordField password = new JPasswordField(20);
  JButton connect = new JButton("Connect");
  JButton cancel = new JButton("Cancel");
  String uname;
  String pword;void buildConstraints(GridBagConstraints gbc ,
                        int gx,
                        int gy,
                        int gw,
                        int gh,
                        int wx,
                        int wy){
    gbc.gridx = gx;
    gbc.gridy = gy;
    gbc.gridwidth = gw;
    gbc.gridheight = gh;
    gbc.weightx = wx;
    gbc.weighty = wy;
  }  public Logon() {
    super("Database Logon");
    setBounds(400,300,270,170);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    JPanel pane = new JPanel();
    GridBagLayout gb = new GridBagLayout(); //create a grid layout
    GridBagConstraints constraint = new GridBagConstraints(); //create constraint
    pane.setLayout(gb);    //put the "usernameLabel" to the grid layout
    buildConstraints(constraint,0,0,1,1,25,25);
    constraint.fill = GridBagConstraints.NONE;
    constraint.anchor = GridBagConstraints.EAST;
    gb.setConstraints(usernameLabel,constraint);
    pane.add(usernameLabel);    //put the "username" to the grid layout
    username.addKeyListener(this);
    buildConstraints(constraint,1,0,1,1,75,0);
    constraint.fill = GridBagConstraints.HORIZONTAL;
    gb.setConstraints(username,constraint);
    pane.add(username);    //put the "passwordLabel" to the grid layout
    buildConstraints(constraint,0,1,1,1,0,25);
    constraint.fill = GridBagConstraints.NONE;
    constraint.anchor = GridBagConstraints.EAST;
    gb.setConstraints(passwordLabel,constraint);
    pane.add(passwordLabel);    //put the "password" to the grid layout
    password.addKeyListener(this);
    password.setEchoChar('*');
    buildConstraints(constraint,1,1,1,1,0,0);
    constraint.fill = GridBagConstraints.HORIZONTAL;
    gb.setConstraints(password,constraint);
    pane.add(password); 
    //put the "connect" button to the grid layout
     connect.addActionListener(this);
    buildConstraints(constraint,0,3,1,1,0,25);
    constraint.fill = GridBagConstraints.NONE;
    constraint.anchor = GridBagConstraints.CENTER;
    gb.setConstraints(connect,constraint);
    pane.add(connect);    //put the "cancel" button to the grid layout
    cancel.addActionListener(this);
    buildConstraints(constraint,1,3,1,1,0,25);
    constraint.fill = GridBagConstraints.NONE;
    constraint.anchor = GridBagConstraints.WEST;
    gb.setConstraints(cancel,constraint);
    pane.add(cancel);    setContentPane(pane);
    show();
  }
  public static void main(String[] args){
    Logon log = new Logon();  }
  public void keyPressed(KeyEvent kevt){}
  public void keyReleased(KeyEvent kevt){}
  
  public void keyTyped(KeyEvent kevt){
    Object ksrc = kevt.getSource();
    if(ksrc == username){
     uname = kevt.paramString();
    }
    if (ksrc == password){
     pword = kevt.paramString();
    }
  }
  
  public void actionPerformed(ActionEvent evt){
    Object src = evt.getSource();
    //若点击“Cancel”按钮，则退出程序
    if (src == cancel)
     System.exit(0);
   //若点击“Connect”按钮，则连接数据库，并将查询的结果写入到一个文本文件中
    else if (src == connect)      {DBConnection conn = new DBConnection("jdbc:oracle:thin:@test:1521:test",uname,pword);
      System.exit(0);
    }    }
}
我调试了一下代码，uname只有一个字符。比如我输入“test”，那么uname会分别为“t”、“e”、“s”、“t”。是我的程序哪里有问题吗？怎样才能使uname的值为输入的“test”？望高手指教！

Answer 1

package tony.test;import javax.swing.*;
import java.awt.*;
import java.awt.event.*;public class Logon extends JFrame implements ActionListener, KeyListener {    JLabel usernameLabel = new JLabel("Username :", JLabel.LEFT);
    JTextField username = new JTextField(20);
    JLabel passwordLabel = new JLabel("Password :", JLabel.LEFT);
    JPasswordField password = new JPasswordField(20);
    JButton connect = new JButton("Connect");
    JButton cancel = new JButton("Cancel");
    String uname;
    String pword;    void buildConstraints(GridBagConstraints gbc, int gx, int gy, int gw,
            int gh, int wx, int wy) {
        gbc.gridx = gx;
        gbc.gridy = gy;
        gbc.gridwidth = gw;
        gbc.gridheight = gh;
        gbc.weightx = wx;
        gbc.weighty = wy;
    }    public Logon() {
        super("Database Logon");
        setBounds(400, 300, 270, 170);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        JPanel pane = new JPanel();
        GridBagLayout gb = new GridBagLayout(); // create a grid layout
        GridBagConstraints constraint = new GridBagConstraints(); // create
        // constraint
        pane.setLayout(gb);        // put the "usernameLabel" to the grid layout
        buildConstraints(constraint, 0, 0, 1, 1, 25, 25);
        constraint.fill = GridBagConstraints.NONE;
        constraint.anchor = GridBagConstraints.EAST;
        gb.setConstraints(usernameLabel, constraint);
        pane.add(usernameLabel);        // put the "username" to the grid layout
        username.addKeyListener(this);
        buildConstraints(constraint, 1, 0, 1, 1, 75, 0);
        constraint.fill = GridBagConstraints.HORIZONTAL;
        gb.setConstraints(username, constraint);
        pane.add(username);        // put the "passwordLabel" to the grid layout
        buildConstraints(constraint, 0, 1, 1, 1, 0, 25);
        constraint.fill = GridBagConstraints.NONE;
        constraint.anchor = GridBagConstraints.EAST;
        gb.setConstraints(passwordLabel, constraint);
        pane.add(passwordLabel);        // put the "password" to the grid layout
        password.addKeyListener(this);
        password.setEchoChar('*');
        buildConstraints(constraint, 1, 1, 1, 1, 0, 0);
        constraint.fill = GridBagConstraints.HORIZONTAL;
        gb.setConstraints(password, constraint);
        pane.add(password);        // put the "connect" button to the grid layout
        connect.addActionListener(this);
        buildConstraints(constraint, 0, 3, 1, 1, 0, 25);
        constraint.fill = GridBagConstraints.NONE;
        constraint.anchor = GridBagConstraints.CENTER;
        gb.setConstraints(connect, constraint);
        pane.add(connect);        // put the "cancel" button to the grid layout
        cancel.addActionListener(this);
        buildConstraints(constraint, 1, 3, 1, 1, 0, 25);
        constraint.fill = GridBagConstraints.NONE;
        constraint.anchor = GridBagConstraints.WEST;
        gb.setConstraints(cancel, constraint);
        pane.add(cancel);        setContentPane(pane);
        show();
    }    public static void main(String[] args) {
        Logon log = new Logon();    }    public void keyPressed(KeyEvent kevt) {
    }    public void keyReleased(KeyEvent kevt) {
    }    public void keyTyped(KeyEvent kevt) {
        Object ksrc = kevt.getSource();
        if (ksrc == username) {
            uname = kevt.paramString();
        }
        if (ksrc == password) {
            pword = kevt.paramString();
        }
    }    public void actionPerformed(ActionEvent evt) {
        Object src = evt.getSource();
        // 若点击“Cancel”按钮，则退出程序
        if (src == cancel) {
            System.exit(0);
        }
        // 若点击“Connect”按钮，则连接数据库，并将查询的结果写入到一个文本文件中
        else if (src == connect) {
            //test code
            uname = username.getText().trim();
            pword = password.getText().trim();
            System.out.println(uname);
            System.out.println(pword);
            
            // TODO: write your login code here 
        }    }
}

Answer 2

pword = password.getText().trim();
该语句有问题，提示“getText() in javax.swing.JPasswordFiled has been deprecated”。password和username不是同一类型的对象。

Answer 3

把pword = password.getText().trim();
改成            pword = new String(password.getPassword());
            pword.trim();

Answer 4

我将：
public void keyPressed(KeyEvent kevt) {
    }    public void keyReleased(KeyEvent kevt) {
    }    public void keyTyped(KeyEvent kevt) {
        Object ksrc = kevt.getSource();
        if (ksrc == username) {
            uname = kevt.paramString();
        }
        if (ksrc == password) {
            pword = kevt.paramString();
        }
    }
给去掉，也还是可以运行的。那我就奇怪了，KeyListener什么时候用呀？

Answer 5

对事件还是不是了解的太清楚。还请高手指教一二。最好能给个教程的url。谢了！