Chapter 4. Creating a web application
Create a web application containing a servlet that returns the user name obtained from the logged-in user’s principal and attributes. If there is no logged-in user, the servlet returns the text "NO AUTHENTICATED USER".
Prerequisites
- You have created a Maven project.
- JBoss EAP is running.
Procedure
Create a directory to store the Java files.
Syntax
$ mkdir -p src/main/java/<path_based_on_artifactID>
Example
$ mkdir -p src/main/java/com/example/app
Navigate to the new directory.
Syntax
$ cd src/main/java/<path_based_on_artifactID>
Example
$ cd src/main/java/com/example/app
Create a file
SecuredServlet.javawith the following content:package com.example.app; import java.io.IOException; import java.io.PrintWriter; import java.security.Principal; import java.util.ArrayList; import java.util.Collection; import java.util.Iterator; import java.util.List; import java.util.Set; import jakarta.servlet.ServletException; import jakarta.servlet.annotation.WebServlet; import jakarta.servlet.http.HttpServlet; import jakarta.servlet.http.HttpServletRequest; import jakarta.servlet.http.HttpServletResponse; import org.wildfly.security.auth.server.SecurityDomain; import org.wildfly.security.auth.server.SecurityIdentity; import org.wildfly.security.authz.Attributes; import org.wildfly.security.authz.Attributes.Entry; /** * A simple secured HTTP servlet. It returns the user name and * attributes obtained from the logged-in user's Principal. If * there is no logged-in user, it returns the text * "NO AUTHENTICATED USER". */ @WebServlet("/secured") public class SecuredServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { try (PrintWriter writer = resp.getWriter()) { Principal user = req.getUserPrincipal(); SecurityIdentity identity = SecurityDomain.getCurrent().getCurrentSecurityIdentity(); Attributes identityAttributes = identity.getAttributes(); Set <String> keys = identityAttributes.keySet(); String attributes = "<ul>"; for (String attr : keys) { attributes += "<li> " + attr + " : " + identityAttributes.get(attr).toString() + "</li>"; } attributes+="</ul>"; writer.println("<html>"); writer.println(" <head><title>Secured Servlet</title></head>"); writer.println(" <body>"); writer.println(" <h1>Secured Servlet</h1>"); writer.println(" <p>"); writer.print(" Current Principal '"); writer.print(user != null ? user.getName() : "NO AUTHENTICATED USER"); writer.print("'"); writer.print(user != null ? "\n" + attributes : ""); writer.println(" </p>"); writer.println(" </body>"); writer.println("</html>"); } } }In the application root directory, compile your application with the following command:
$ mvn package ... [INFO] ------------------------------------------------------------------------ [INFO] BUILD SUCCESS [INFO] ------------------------------------------------------------------------ [INFO] Total time: 1.015 s [INFO] Finished at: 2022-04-28T17:48:53+05:30 [INFO] ------------------------------------------------------------------------
Deploy the application.
$ mvn wildfly:deploy
Verification
In a browser, navigate to
http://localhost:8080/simple-webapp-example/secured.You get the following message:
Secured Servlet Current Principal 'NO AUTHENTICATED USER'
Because no authentication mechanism is added, you can access the application.
You can now secure this application by using a security domain so that only authenticated users can access it.
