ログインページを表示するアプレットを作成しました。アプレットのコードは次のとおりです。
import java.net.*;
import java.awt.event.*;
import java.awt.*;
import javax.swing.*;
/**
* Class login - write a description of the class here
*
* @author (your name)
* @version (a version number)
*/
public class login extends JApplet
implements ActionListener
{
// instance variables - replace the example below with your own
private JTextField input;
private JTextField pass;
private JPasswordField pwd;
private final String LOGIN = "LOGIN";
private final String PASSWORD = "PASSWORD";
private final String CLEAR = "CLEAR";
private final String Fgt_pwd="Forgot Password";
private final String REGISTER="REGISTER";
/**
* Called by the browser or applet viewer to inform this JApplet that it
* has been loaded into the system. It is always called before the first
* time that the start method is called.
*/
public void init()
{
// provide any initialisation necessary for your JApplet
}
public void actionPerformed(ActionEvent e)
{
String command = e.getActionCommand();
if(LOGIN.equals(command))
{
input.setText("Login Successful");
try{
URL url = new URL(getDocumentBase(), "feedback.html");
getAppletContext().showDocument(url);
}catch(MalformedURLException ex){
showStatus("URL not found");
}
}
else if(CLEAR.equals(command))
input.setText("");
else if(Fgt_pwd.equals(command))
input.setText("Redirecting to Forgot Password Page");
else if(REGISTER.equals(command))
input.setText("Redirecting to Registration Page");
}
/**
* Called by the browser or applet viewer to inform this JApplet that it
* should start its execution. It is called after the init method and
* each time the JApplet is revisited in a Web page.
*/
public void start()
{
// provide any code requred to run each time
// web page is visited
// this is a workaround for a security conflict with some browsers
// including some versions of Netscape & Internet Explorer which do
// not allow access to the AWT system event queue which JApplets do
// on startup to check access. May not be necessary with your browser.
Container contentPane = getContentPane();
JScrollPane sPane = new JScrollPane();
JPanel pContPanel = new JPanel();
pContPanel.setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints(6, 5, 1, 1, 0, 0, GridBagConstraints.CENTER, GridBagConstraints.HORIZONTAL, new Insets(10,10,10,10), 20, 20);
Font myFont = new Font("Ariel",Font.BOLD,22);
JLabel mtitle = new JLabel("WELCOME TO D.A.S.H.");
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.gridx = 1;
gbc.gridy = 0;
gbc.gridwidth = 1;
pContPanel.add(mtitle, gbc);
mtitle.setFont(myFont);
//Adding the title
JLabel title = new JLabel("SIGN IN TO YOUR ACCOUNT");
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.gridx = 0;
gbc.gridy = 1;
gbc.gridwidth = 3;
pContPanel.add(title, gbc);
//Create upper left part for Login ID
JPanel panel1 = new JPanel();
JLabel prompt = new JLabel("Enter Login ID");
panel1.add(prompt);
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.gridx = 0;
gbc.gridy = 2;
gbc.gridwidth = 1;
pContPanel.add(panel1, gbc);
// prompt.setAlignmentX(Component.LEFT_ALIGNMENT);
//adding the textfield for username
input = new JTextField(15);
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.gridx = 1;
gbc.gridy = 2;
gbc.gridwidth = 2;
pContPanel.add(input, gbc);
//adding the label for password
JPanel passPanel=new JPanel();
JLabel passLabel = new JLabel("Enter Password");
passPanel.add(passLabel);
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.gridx = 0;
gbc.gridy = 3;
gbc.gridwidth = 1;
pContPanel.add(passPanel, gbc);
//adding the password field
pwd=new JPasswordField(15);
pwd.setEchoChar('*');
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.gridx = 1;
gbc.gridy = 3;
gbc.gridwidth = 2;
pContPanel.add(pwd, gbc);
JLabel rtitle = new JLabel("NEW USER? CLICK HERE TO REGISTER.");
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.gridx = 0;
gbc.gridy = 5;
gbc.gridwidth = 3;
pContPanel.add(rtitle, gbc);
//Now create button for login
JButton bLogin = new JButton(LOGIN);
bLogin.addActionListener(this);
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.gridx = 0;
gbc.gridy = 4;
gbc.gridwidth = 1;
pContPanel.add(bLogin, gbc);
//now create button for clear
JButton bPassword = new JButton(CLEAR);
bPassword.addActionListener(this);
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.gridx = 1;
gbc.gridy = 4;
gbc.gridwidth = 1;
pContPanel.add(bPassword, gbc);
//now create button for forgot password
JButton bForgotPwd = new JButton(Fgt_pwd);
bForgotPwd.addActionListener(this);
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.gridx = 2;
gbc.gridy = 4;
pContPanel.add(bForgotPwd, gbc);
JButton bRegister = new JButton(REGISTER);
bRegister.addActionListener(this);
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.gridx = 2;
gbc.gridy = 5;
gbc.gridwidth = 1;
pContPanel.add(bRegister, gbc);
//adding the panel to the scrollpane
sPane.setViewportView(pContPanel);
//adding scrollpane to the ContentPane
contentPane.add(sPane, BorderLayout.CENTER);
}
今のところ何も入っていないペイントメソッドもあります。コードの出力は完璧です。上記のコードに paint メソッドを追加して背景色を追加しようとすると、次のようになります。
public void paint(Graphics g)
{
// simple text displayed on applet
setBackground(Color.blue);
}
私が見ている出力は、最初に表示されていた他のすべてのボタンとテキストフィールドを隠している（appletviewerの）背景が青色のウィンドウです。ブラウザで出力すると、背景色のない元の出力が表示されます。
アプレットの見栄えを良くするために、グラフィック (背景とテキストの色、場合によっては画像) を追加する方法を教えてください。（大学のミニプロジェクトとして提出する必要があります）。