Boost Your Login Security with These Struts 2.0 Code Examples Using Interceptors

Table of content

  1. Introduction
  2. Why Struts 2.0 Interceptors are Important for Login Security?
  3. Example 1: Custom Interceptor for Token-based Authentication
  4. Example 2: Implementing Captcha Interceptor to Prevent Brute Force Attacks
  5. Example 3: Using Validation Interceptor to Validate User Input and Prevent SQL Injection
  6. Example 4: Implementing Session Timeout Interceptor to Prevent Session Hijacking
  7. Conclusion
  8. References


Secure login is a crucial aspect of online security that helps protect user data and privacy against unauthorized access or hacking attempts. One way to enhance login security in web applications is by using Struts 2.0 code examples that utilize interceptors. Struts 2.0 is a powerful framework for building web applications that provides built-in support for interceptors. Interceptors are used to enhance the functionality of an application by intercepting requests and responses, modifying them if necessary, and passing them back to the application.

In this article, we will explore some Struts 2.0 code examples that use interceptors to boost login security in web applications. These examples will demonstrate how to implement common security features like encryption, session management, and access control. By following these examples, developers can improve the security of their web applications and protect user data from potential threats. With Struts 2.0 and interceptors, developers can easily add layers of security to their web applications and keep up with the ever-evolving landscape of cyber threats.

Why Struts 2.0 Interceptors are Important for Login Security?

Struts 2.0 is an open-source framework used to develop web applications in Java. It comes with a range of built-in features and functionalities that simplify web development, including interceptors.

Interceptors in Struts 2.0 are objects that enable developers to intercept and customize the behavior of requests and responses. This means that developers can use them to implement additional security measures during login authentication.

Here are some reasons why Struts 2.0 interceptors are important for login security:

  1. Authentication Checks: Interceptors can be used to add custom authentication checks during the login process. For example, you could use an interceptor to check if a user has entered a valid username and password, or if their account is active and not locked out.

  2. Session Management: Interceptors can also be used to manage user sessions, ensuring that users are only able to access resources that they are authorized to view. This can include checking session timeouts, expiring sessions on logout, and preventing session hijacking attacks.

  3. Cross-Site Request Forgery (CSRF) Prevention: Interceptors can be used to mitigate CSRF attacks, which occur when an attacker tricks a user into submitting a request on their behalf. By implementing CSRF prevention measures in interceptors, developers can thwart such attacks and ensure that user input is validated before processing.

Overall, Struts 2.0 interceptors are an important tool for developers looking to boost login security in their web applications. By leveraging the built-in interceptors and implementing custom interceptors, developers can create more robust and secure authentication systems.

Example 1: Custom Interceptor for Token-based Authentication

Token-based authentication is a popular approach for securing web applications. It works by validating a token (a unique identifier) that is generated by the server after a successful login. To implement token-based authentication in a Struts 2.0 application, you can create a custom interceptor that verifies the token on each request.

Here's an example of a custom interceptor for token-based authentication:

public class TokenInterceptor extends AbstractInterceptor {

  public String intercept(ActionInvocation invocation) throws Exception {
    Map<String, Object> session = invocation.getInvocationContext().getSession();
    String token = (String)session.get("token");

    if (token != null && token.equals(getRequestToken())) {
      return invocation.invoke();
    } else {
      return "invalidToken";

  private String getRequestToken() {
    HttpServletRequest request = ServletActionContext.getRequest();
    return request.getParameter("token");

The TokenInterceptor class extends AbstractInterceptor and overrides the intercept() method. This method first retrieves the session object from the ActionInvocation object, and then gets the token value that was stored in the session during login.

It then uses the getRequestToken() method to obtain the value of the token parameter that was sent with the request. If the token values match, the method allows the request to continue by invoking invocation.invoke(). If the token values do not match, the method returns the string "invalidToken", which can be used to display an error message to the user.

To use this interceptor in your Struts 2.0 application, you need to define it in your struts.xml configuration file. Here's an example:

  <interceptor name="tokenInterceptor" class="com.example.TokenInterceptor"/>
  <interceptor-stack name="defaultStack">
    <interceptor-ref name="tokenInterceptor"/>
    <interceptor-ref name="basicStack"/>

<default-interceptor-ref name="defaultStack"/>

This configuration defines a new interceptor called tokenInterceptor and adds it to the defaultStack interceptor stack, which also includes the default interceptor stack basicStack. It then specifies defaultStack as the default interceptor stack for all actions.

With this configuration in place, any action that needs token-based authentication can simply use the defaultStack interceptor stack, and the tokenInterceptor will automatically be applied.

Example 2: Implementing Captcha Interceptor to Prevent Brute Force Attacks

One common type of attack is known as a brute force attack, where attackers systematically try different passwords until they find the right one. This can be prevented by using a captcha, which requires users to identify objects or characters on the screen to prove that they are human. In Struts 2.0, this can be implemented using the Captcha Interceptor.

First, a captcha library such as reCaptcha must be integrated into the Struts 2.0 project. This can be done by adding the necessary dependencies and including the captcha JSP tag library in the relevant JSP files.

Next, the Captcha Interceptor must be configured in the struts.xml file. This involves specifying the captcha validation key, error messages, and success and failure actions.

Finally, the Captcha Interceptor must be added to the interceptor stack for any actions that require captcha validation. This can be done in the same struts.xml file by specifying the desired order of interceptors.

With the Captcha Interceptor in place, any attempt at a brute force attack on an action requiring captcha validation will be thwarted. This provides an extra layer of security for login credentials and helps prevent unauthorized access to sensitive information.

Example 3: Using Validation Interceptor to Validate User Input and Prevent SQL Injection

The Validation Interceptor is a powerful tool that can help prevent SQL injection attacks by validating user input before it is sent to the database. This interceptor can be used in conjunction with other interceptors, such as the Parameter Interceptor, to provide a comprehensive security framework for your Struts 2.0 application.

To use the Validation Interceptor, you simply configure it in your struts.xml file and specify the validation rules that should be applied to each action. These rules can be defined using the XML validation framework or with annotations in your action classes.

By validating user input, you can prevent attackers from injecting malicious SQL code into your database, which can be used to steal sensitive information or gain unauthorized access to your system. With the Validation Interceptor, you can ensure that all user input is properly sanitized and validated before it is used in your application.

Overall, the Validation Interceptor is an essential tool for any Struts 2.0 application that requires secure user authentication and input validation. By using this interceptor in combination with other security measures, you can help to ensure that your application remains secure and your users' data remains protected.

Example 4: Implementing Session Timeout Interceptor to Prevent Session Hijacking

Session hijacking is one of the most common attacks on web applications where an attacker takes over a valid user session to gain unauthorized access to sensitive information. To prevent this, it's important to set a time limit on how long a user's session remains active. This is where the Session Timeout Interceptor comes in.

To implement this interceptor in Struts 2.0, you first need to create a SessionTimeoutInterceptor class that extends the AbstractInterceptor class. In this class, you'll need to override the intercept() method, which is called every time an action is invoked.

Within the intercept() method, you'll need to check if the user's session exists and if its creation time exceeds the maximum idle time that you've set. If the session has timed out, the user will be redirected to the login page. Otherwise, the interceptor will allow the action to be invoked.

Here's an example code snippet that shows how to implement the Session Timeout Interceptor:

public class SessionTimeoutInterceptor extends AbstractInterceptor {

    private static final long serialVersionUID = 1L;
    private int sessionTimeout; // in seconds
    private String timeoutPage;

    public String getTimeoutPage() {
        return timeoutPage;

    public void setTimeoutPage(String timeoutPage) {
        this.timeoutPage = timeoutPage;

    public int getSessionTimeout() {
        return sessionTimeout;

    public void setSessionTimeout(int sessionTimeout) {
        this.sessionTimeout = sessionTimeout;

    public String intercept(ActionInvocation invocation) throws Exception {
        Map<String, Object> session = invocation.getInvocationContext().getSession();
        if (session.containsKey("user")) {
            long lastAccessedTime = session.getLastAccessedTime();
            long currentTimeMillis = System.currentTimeMillis();
            long timeElapsed = (currentTimeMillis - lastAccessedTime) / 1000;
            if (timeElapsed > sessionTimeout) {
                return timeoutPage;
            else {
                session.put("user", session.get("user"));
                return invocation.invoke();
        return invocation.invoke();


In this example, the session timeout is set to 10 minutes (600 seconds) and the user is redirected to a timeout page if their session has expired.

You can use this interceptor by configuring it in the struts.xml file:

    <interceptor name="sessionTimeout"
        <param name="sessionTimeout">600</param>
        <param name="timeoutPage">/</param>
    <interceptor-stack name="secureStack">
        <interceptor-ref name="sessionTimeout" />
        <interceptor-ref name="defaultStack" />

<default-interceptor-ref name="secureStack"></default-interceptor-ref>

In this configuration, the Session Timeout Interceptor is added to the secureStack interceptor stack, which is then used as the default interceptor for all actions.

By implementing the Session Timeout Interceptor, you can significantly reduce the risk of session hijacking and improve the security of your web application.



Implementing login security measures is crucial in maintaining the integrity of sensitive data and keeping user accounts safe from potential hacks. Struts 2.0 provides an easy-to-use solution for boosting login security with the use of interceptors.
By incorporating interceptors into our code, we can add an extra layer of protection to our login system, making it more robust and secure.
In this article, we've looked at various examples of how interceptors can be used to implement security measures such as CSRF protection, password hashing, and captcha verification.
Remember, implementing security measures is an ongoing process, and we must continuously evaluate and update our security measures to stay ahead of potential threats. Struts 2.0 provides us with the tools we need to build a secure login system, but it's up to us to use them effectively.


  1. Apache Struts 2 Documentation:
  2. Interceptors in Struts 2:
  3. OWASP Top 10:
  4. User Login Best Practices:
  5. Java Security:
  6. Spring Security:
  7. Java Login Example:
  8. Struts 2 Example:
  9. Java Web Application Security:
  10. Java Web Security Plugins:
As a developer, I have experience in full-stack web application development, and I'm passionate about utilizing innovative design strategies and cutting-edge technologies to develop distributed web applications and services. My areas of interest extend to IoT, Blockchain, Cloud, and Virtualization technologies, and I have a proficiency in building efficient Cloud Native Big Data applications. Throughout my academic projects and industry experiences, I have worked with various programming languages such as Go, Python, Ruby, and Elixir/Erlang. My diverse skillset allows me to approach problems from different angles and implement effective solutions. Above all, I value the opportunity to learn and grow in a dynamic environment. I believe that the eagerness to learn is crucial in developing oneself, and I strive to work with the best in order to bring out the best in myself.
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