struts2 check permission interceptor

Question

In my current struts2 + spring web application, I have my custom userSessionInterceptor that works well. I now also want to start enforcing user roles as well. I have done many online researches, seems like there are many ways to do it, e.g. exceptions, sendRedirect

What is the most proper way to do this? I already have the user role saved in the user session and I have no problem detecting and spotting out the error. The only thing I need to decide is how to react to it when the permission is not right.

In the interceptator, I know i can return "xxx" and get to the "xxx" action. However, what I want to achieve is that when the user tries to do something that they have no permission, a message will be displayed. I assume I can return back to the previous page and add a parameter to the url.

Any tips on this?

Thanks

Answer 1

Here is a sample program.

RoleInterceptor.java

package com.sample.common.interceptor;

import javax.servlet.http.HttpSession;

import org.apache.struts2.ServletActionContext;

import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.Interceptor;
import com.opensymphony.xwork2.util.ValueStack;

public class RoleInterceptor implements Interceptor {

    private static final long serialVersionUID = 5031826078189685536L;

    @Override
    public void init() {

    }

    @Override
    public void destroy() {

    }

    @Override
    public String intercept(ActionInvocation actionInvocation) {

        String result = null;
        try {
            ActionContext actionContext = actionInvocation
                    .getInvocationContext();

            ValueStack vStack = actionContext.getValueStack();
            HttpSession httpSession = ServletActionContext.getRequest()
                    .getSession();

            StringBuilder actionUrl = new StringBuilder(actionInvocation
                    .getProxy().getNamespace());
            actionUrl.append("/");
            actionUrl.append(actionInvocation.getProxy().getActionName());

            if (httpSession != null) {

                boolean hasPermission = true; // if the role has the permission

                if (hasPermission) {

                    result = actionInvocation.invoke();

                } else {

                    vStack.set("userMsg",
                            "You are not authorized to access this link");
                    result = "user.unauthorized";
                }
            } else {

                vStack.set("userMsg", "Please login to your account");
                result = "user.login";
            }

        } catch (Exception e) {
            e.printStackTrace();
        }

        return result;

    }

}

struts.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
"http://struts.apache.org/dtds/struts-2.0.dtd">
<struts>
    <package name="userRoleInterceptor">
        <interceptors>
            <interceptor name="userRole"
                class="com.sample.common.interceptor.RoleInterceptor" />
        </interceptors>
    </package>
    <package name="user" namespace="/user" extends="struts-default, json-default, userRoleInterceptor">
        <action name="user_details" method="getUserDetails"
            class="com.sample.user.web.action.User">
            <interceptor-ref name="userRole"/>
            <interceptor-ref name="store">
                <param name="operationMode">RETRIEVE</param>
            </interceptor-ref>
            <result name="success">userDetails.jsp</result>
            <result name="input">/common/error.jsp</result>
            <result name="busy" type="redirectAction" >/common/busy.jsp</result>
            <result name="error" type="redirectAction" >/common/test.jsp</result>
            <result name="user.login" type="redirectAction" >/common/login.jsp</result>
            <result name="user.unauthorized" type="redirectAction" >/common/unauthorizedUser.jsp</result>
        </action>
    </package>
</struts>