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The Java EE 6 Tutorial, Volume I

Using Programmatic Security with Web Applications

Programmatic security is used by security-aware applications when declarative security alone is not sufficient to express the security model of the application. The following topics are discussed in this section:

Authenticating Users Programmatically

Servlet 3.0 specifies the following methods of the HttpServletRequest interface that enable you to authenticate users for a web application programmatically:

The following example code shows how to use the login and logout methods:

package test;

import java.io.IOException;
import java.io.PrintWriter;
import java.math.BigDecimal;
import javax.ejb.EJB;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet(name="TutorialServlet", urlPatterns={"/TutorialServlet"})
public class TutorialServlet extends HttpServlet {
    @EJB
    private ConverterBean converterBean;

    /**
     * Processes requests for both HTTP <code>GET</code> 
		* and <code>POST</code> methods.
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    protected void processRequest(HttpServletRequest request, 
			HttpServletResponse response)
    throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        try {

            out.println("<html>");
            out.println("<head>");
            out.println("<title>Servlet TutorialServlet</title>");
            out.println("</head>");
            out.println("<body>");
            request.login("TutorialUser", "TutorialUser");
            BigDecimal result = converterBean.dollarToYen(new BigDecimal("1.0"));
            out.println("<h1>Servlet TutorialServlet result of dollarToYen= " + result + "</h1>");
            out.println("</body>");
            out.println("</html>");
        } catch (Exception e) {
            throw new ServletException(e);
        } finally {
            request.logout();
            out.close();
        }
    }
}

This code sample shows how to use the authenticate method:

package com.sam.test;

import java.io.*;

import javax.servlet.*;
import javax.servlet.http.*;

public class TestServlet extends HttpServlet {

    protected void processRequest(HttpServletRequest request, 
			HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        try {
            request.authenticate(response);
            out.println("Authenticate Successful");

        } finally {
            out.close();
        }
    }

Checking Caller Identity Programmatically

In general, security management should be enforced by the container in a manner that is transparent to the web component. The security API described in this section should be used only in the less frequent situations in which the web component methods need to access the security context information.

Servlet 3.0 specifies the following methods of the HttpServletRequest interface that enable you to verify a caller's identity programmatically, and to use that information to grant or deny access to data:

Your application can make business logic decisions based on the information obtained using these APIs.

Example Code for Programmatic Security

The following code demonstrates the use of programmatic security for the purposes of programmatic login. 

package enterprise.programmatic_login;

import java.io.*;
import java.net.*;

import javax.annotation.security.DeclareRoles;
import javax.servlet.*;
import javax.servlet.http.*;

@DeclareRoles("javaee6user")
public class LoginServlet extends HttpServlet {

    /** 
     * Processes requests for both HTTP GET and POST methods.
     * @param request servlet request
     * @param response servlet response
     */
    protected void processRequest(HttpServletRequest request, 
				 HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        try {
            String userName = request.getParameter("txtUserName");
            String password = request.getParameter("txtPassword");
            
            out.println("Before Login"+"<br><br>");
            out.println("IsUserInRole?.." + request.isUserInRole("javaee6user")+"<br>");
            out.println("getRemoteUser?.." + request.getRemoteUser()+"<br>");
            out.println("getUserPrincipal?.." + request.getUserPrincipal()+"<br>");
            out.println("getAuthType?.." + request.getAuthType()+"<br><br>");
            
            try {
            request.login(userName, password); 
            }catch(ServletException ex) {
                out.println("Login Failed with a ServletException.." + 
						ex.getMessage());
                return;
            }
            out.println("After Login..."+"<br><br>");
            out.println("IsUserInRole?.." + request.isUserInRole("javaee6user")+"<br>");
            out.println("getRemoteUser?.." + request.getRemoteUser()+"<br>");
            out.println("getUserPrincipal?.." + request.getUserPrincipal()+"<br>");
            out.println("getAuthType?.." + request.getAuthType()+"<br><br>");
            
            request.logout();
            out.println("After Logout..."+"<br><br>");
            out.println("IsUserInRole?.." + request.isUserInRole("javaee6user")+"<br>");
            out.println("getRemoteUser?.." + request.getRemoteUser()+"<br>");
            out.println("getUserPrincipal?.." + request.getUserPrincipal()+"<br>");
            out.println("getAuthType?.." + request.getAuthType()+"<br>");
            
            
        } finally {
            out.close();
        }
    }

       /** 
     * Handles the HTTP <code>GET</code> method.
     * @param request servlet request
     * @param response servlet response
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /** 
     * Handles the HTTP <code>POST</code> method.
     * @param request servlet request
     * @param response servlet response
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /** 
     * Returns a short description of the servlet.
     */
    public String getServletInfo() {
        return "Short description";
    }
}

This servlet displays the name of the user who is currently logged in, then prompts a user for login, and prints out the information again, then logs out the user and prints the information again in order to demonstrate the effect of the login and logout methods. The application deployment descriptor, web.xml, includes a login-config element that specifies basic authentication. The runtime deployment descriptor, sun-web.xml, includes a role-mapping of the user of the application to a group of the same name on the Enterprise Server.

Declaring and Linking Role References

A security role reference defines a mapping between the name of a role that is called from a web component using isUserInRole(String role) and the name of a security role that has been defined for the application. If no <security-role-ref> element is declared in a deployment descriptor, and the isUserInRole method is called, the container defaults to checking the provided role name against the list of all security roles defined for the web application. Using the default method instead of using the security-role-ref element limits your flexibility to change role names in an application without also recompiling the servlet making the call.

The security-role-ref element is used when an application uses the HttpServletRequest.isUserInRole(String role) method. The value passed to the isUserInRole method is a String representing the role name of the user. The value of the role-name element must be the String used as the parameter to the HttpServletRequest.isUserInRole(String role) method. The role-link must contain the name of one of the security roles defined in the security-role elements. The container uses the mapping of security-role-ref to security-role when determining the return value of the call.

For example, to map the security role reference cust to the security role with role name bankCustomer, the syntax would be: 

<servlet>
...
    <security-role-ref>
        <role-name>cust</role-name>
        <role-link>bankCustomer</role-link>
    </security-role-ref>
...
</servlet>

In this case, if the servlet called by a user belonging to the bankCustomer security role made the API call, isUserInRole("cust") would return true.

The <role-link> element in the security-role-ref element must match a <role-name> defined in the <security-role> element of the same web.xml deployment descriptor, as shown here:

<security-role>
    <role-name>bankCustomer</role-name>
</security-role>

A security role reference, including the name defined by the reference, is scoped to the component whose deployment descriptor contains the security-role-ref deployment descriptor element.