使用JTextField和JPasswordField类来创建和操作2个文本字段。接收用户输入时，当按下回车键时将会产生一个ActionEvent。在事件处理程序中判断用户输入的用户名与密码名是否正确，会弹出相应消息对话框进行回应。并对程序进行测试及分析。-Using the JTextField and JPasswordField class to create and operate two text fields. Receiving user input, and when pressed the Enter key will be generated when an ActionEvent. In the event handler to check the user name entered by the user name and password are correct, a message will pop up dialog box for the appropriate response. And procedures for testing and analysis.