How to code a support class for external Java clients (outside of the SilverStream development environment) that handles logins when the SilverStream Server calls back for user authentication.
See the chapter on writing external Java clients in the Programmer's Guide |
The login handler technique involves coding a class that obtains a username and password, then returns them to the SilverStream server. The design of this class depends on how you go about getting those values:
If you want to obtain the username and password in some other way (such as from command-line arguments), you can use one of the provided classes as a starting point and modify it.
This implementation of the login handler prompts for a username and password by using standard output/input.
Related reading
package extjtech;
import java.io.*;
import com.sssw.rt.util.*;
// The LoginHandler class shows how you can code a
// SilverStream login handler for use in external Java
// clients. You'll supply an instance of this class in the
// AgRuntime.init() method when preparing to connect your
// client to a SilverStream server. This enables the server
// to call back to that LoginHandler instance when it
// requires user authentication.
//
// LoginHandler implements the SilverStream interface
// AgiUserLogin, which has one method: prompt(). You must
// code that method to prompt the user for name and password,
// then return those values to the server (in an instance of
// the SilverStream class AgoUserLoginInfo).
//
// This example prompts the user by writing prompt text to
// standard output and reading data entry from standard
// input. Alternatively, you could display a dialog (as
// shown in class LoginHandlerDlg) or read command-line args
// to obtain the name and password.
public class LoginHandler implements AgiUserLogin {
public AgoUserLoginInfo prompt(String realm,
String username,
boolean forceDialog) {
BufferedReader in = null;
String user = null;
String password = null;
try {
// Prepare to read data entered from standard input.
in = new BufferedReader(new InputStreamReader(System.in));
// Ask the user to log in to this security realm.
System.out.println("Please log in for " + realm);
// Obtain the username.
System.out.print("username: ");
System.out.flush();
user = in.readLine();
// If a username was entered, obtain the password.
// Note: A limitation of this approach is that the
// password displays on the user's screen.
if (user != null && user.length() != 0) {
System.out.print("password: ");
System.out.flush();
password = in.readLine();
}
}
catch (IOException ex) {
System.out.println("I/O error during login prompt");
ex.printStackTrace();
}
// Return the username and password to the server for
// authentication.
return new AgoUserLoginInfo(user, password);
}
}
When this login handler class runs, it prompts the user as follows:
To learn more about using this class in an application, see any of these related Application Techniques:
This implementation of the login handler prompts for a username and password by displaying a dialog.
package extjtech;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import com.sssw.rt.util.*;
// The LoginHandlerDlg class shows how you can code a
// SilverStream login handler for use in external Java
// clients. You'll supply an instance of this class in the
// AgRuntime.init() method when preparing to connect your
// client to a SilverStream server. This enables the server
// to call back to that LoginHandlerDlg instance when it
// requires user authentication.
//
// LoginHandlerDlg implements the SilverStream interface
// AgiUserLogin, which has one method: prompt(). You must
// code that method to prompt the user for name and password,
// then return those values to the server (in an instance of
// the SilverStream class AgoUserLoginInfo).
//
// This example prompts the user by displaying a dialog.
// Alternatively, you could read standard input (as shown in
// class LoginHandler) or command-line args to obtain the
// name and password.
public class LoginHandlerDlg implements AgiUserLogin {
// Instance variables for the LoginHandlerDlg class.
String user;
String password;
JFrame frame;
JDialog dialog;
JTextField namefield;
JPasswordField passfield;
public AgoUserLoginInfo prompt(String realm,
String username,
boolean forceDialog) {
// Start setting up the dialog to display. Include
// the name of the security realm (supplied by the
// server) in its title.
frame = new JFrame();
dialog = new JDialog(frame, "Login for " + realm, true);
// Set up the username field. If the server supplies a
// username value from a prior login try, display it.
JLabel namelabel = new JLabel("Username: ");
namefield = new JTextField(10);
namefield.setText(username);
// Set up the password field.
JLabel passlabel = new JLabel("Password: ");
passfield = new JPasswordField(10);
passfield.setEchoChar('#');
// Set up the OK button, including an event handler
// that executes when a user clicks the button. This
// event handler obtains the username and password
// entered in the fields, then closes the dialog.
JButton button = new JButton("OK");
button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
user = namefield.getText();
password = new String(passfield.getPassword());
frame.dispose();
}
});
// Lay out the labels in a panel.
JPanel labelpane = new JPanel();
labelpane.setLayout(new GridLayout(0, 1));
labelpane.add(namelabel);
labelpane.add(passlabel);
// Lay out the fields in a panel.
JPanel fieldpane = new JPanel();
fieldpane.setLayout(new GridLayout(0, 1));
fieldpane.add(namefield);
fieldpane.add(passfield);
// Now put everything in another panel: labels on
// left, fields on right, button on bottom.
JPanel contentpane = new JPanel();
contentpane.setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20));
contentpane.setLayout(new BorderLayout());
contentpane.add(labelpane, BorderLayout.CENTER);
contentpane.add(fieldpane, BorderLayout.EAST);
contentpane.add(button, BorderLayout.SOUTH);
// Finish setting up the dialog, then show it.
dialog.setContentPane(contentpane);
dialog.pack();
dialog.setLocation(100, 100);
dialog.setVisible(true);
// Return the username and password to the server for
// authentication.
return new AgoUserLoginInfo(user, password);
}
}
When this login handler class runs, it prompts the user as follows:
To learn more about using this class in an application, see the related Application Technique:
Providing Data to JTables in External Java Clients.
