编写程序，利用JtextField和JpasswordField分别接收用户输入的用户名和密码，并对用户输入的密码进行检验。对于每个用户名有三次密码输入机会。

package beizi;

import java.awt.EventQueue;

import javax.swing.JFrame;

import javax.swing.JLabel;

import java.awt.BorderLayout;

import javax.swing.JButton;

import java.awt.event.ActionListener;

import java.awt.event.ActionEvent;

import javax.swing.JTextField;

import java.awt.Color;

import javax.swing.JCheckBox;

import java.awt.Dimension;

import java.awt.FlowLayout;

import java.awt.GridBagLayout;

import java.awt.GridBagConstraints;

import java.awt.Insets;

import javax.swing.JTextPane;

import java.awt.TextArea;

import java.awt.Label;

import javax.swing.JPasswordField;

import javax.swing.JOptionPane;

public class test {

private JFrame frame;

private JPasswordField passwordField;

private JTextField textField;

/**

* Launch the application.

*/

public static void main(String[] args) {

EventQueue.invokeLater(new Runnable() {

public void run() {

try {

test window = new test();

window.frame.setVisible(true);

} catch (Exception e) {

e.printStackTrace();

}

}

});

}

/**

* Create the application.

*/

public test() {

initialize();

}

/**

* Judge the pwd and username

*/

public void judge() {

}

/**

* Initialize the contents of the frame.

*/

private void initialize() {

frame = new JFrame();

frame.setBounds(100, 100, 450, 300);

frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

frame.getContentPane().setLayout(null);

Label label_2 = new Label("login");//login

label_2.setBounds(141, 31, 139, 23);

frame.getContentPane().add(label_2);

JButton btnNewButton = new JButton("\u767B\u5F55");//登录

btnNewButton.setBounds(168, 198, 93, 23);

btnNewButton.setBackground(Color.LIGHT_GRAY);

btnNewButton.addActionListener(new ActionListener() {

int i = 3;

public void actionPerformed(ActionEvent arg0) {

String usr=textField.getText();

String pwd=passwordField.getText();

while(i!=0) {

i--;

if(usr.equals("123456")&pwd.equals("abc123")) {

JOptionPane.showMessageDialog(null, "登陆成功！欢迎徐小白同学~");

break;

}

else {

JOptionPane.showMessageDialog(null, "账户或密码错误，你还有"+(i)+"次机会");

break;

}

}

if(i==0) {

System.exit(0);

}

}

});

frame.getContentPane().add(btnNewButton);

Label label = new Label("\u5B66\u53F7\uFF1A");//学号

label.setBounds(140, 73, 34, 23);

frame.getContentPane().add(label);

Label label_1 = new Label("\u5BC6\u7801\uFF1A");//密码

label_1.setBounds(140, 121, 34, 23);

frame.getContentPane().add(label_1);

passwordField = new JPasswordField();

passwordField.setBounds(182, 123, 79, 21);

frame.getContentPane().add(passwordField);

textField = new JTextField();

textField.setBounds(182, 73, 79, 21);

frame.getContentPane().add(textField);

textField.setColumns(10);

}

}

丑陋的效果，，，：