How to get Roles from UserPrincipal in Java?

Question

I created a class(Named as CustomRequestWrapper) which is implementing HttpServletRequestWrapper .In CustomRequestWrapper class i am setting user principal.Now in my code i want to get list of roles from the user principal.I tried to use GenericPrincipal Class from tomcat-catalina jar but i am getting casting exception CustomRequestWrapper cannot be cast to GenericPrincipal. Could any one have idea how to get roles from user principal?

Note: I am using Apache Tomcat Server

Here's my code:

public class CustomRequestWrapper extends javax.servlet.http.HttpServletRequestWrapper {

public CustomRequestWrapper(String User,List<String> roles,HttpServletRequest request) {
    super(request);
    this.user=User;
    this.roles=roles;
    this.realRequest=request;
    headerMap = new HashMap();
}
String user;  
List<String> roles = null; 
HttpServletRequest realRequest;  
private Map headerMap;

public void addHeader(String name, String value) {
    headerMap.put(name, new String(value));
}

public Enumeration getHeaderNames() {
    HttpServletRequest request = (HttpServletRequest) getRequest();
    List list = new ArrayList();
    for (Enumeration e = request.getHeaderNames(); e.hasMoreElements();) {
        list.add(e.nextElement().toString());
    }

    for (Iterator i = headerMap.keySet().iterator(); i.hasNext();) {
        list.add(i.next());
    }
    return Collections.enumeration(list);
}

public String getHeader(String name) {
    Object value;
    if ((value = headerMap.get("" + name)) != null)
        return value.toString();
    else
        return ((HttpServletRequest) getRequest()).getHeader(name);
}
     @override
public boolean isUserInRole(String role) {  
    if (roles == null) {  
        return this.realRequest.isUserInRole(role);  
    }  
    return roles.contains(role);  
}  

@override
public Principal getUserPrincipal() {  
    if (this.user == null) {  
        return realRequest.getUserPrincipal();  
    }  

    // make an anonymous implementation to just return our user  
    return new Principal() {  

        public String getName() {       
            return user;  
        }  
    };  
}  

}

Answer 1

From your code, you inject the username and the roles into your CustomRequestWrapper in constructor. As you have overriden getUserPrincipal in CustomRequestWrapper it returns no longer a tomcat GenericPrincipal but your anonymous class that only knows to return the name of the user you gave, this via getName(). You should try to return a tomcat GenericPrincipal through

  @Override
  public Principal getUserPrincipal()
  {
    if (this.user == null)
    {
      return realRequest.getUserPrincipal();
    }

    // return a forged GenericPrincipal
    return new GenericPrincipal(user, "", roles);
  }

Alternatively, you could create a custom implementation of Principal knowing about roles.

That will only work if you successfully inject your user and its roles at CustomRequestWrapper construction.