A Step-by-Step Guide to Extracting Bearer Token from Request Header in Java Spring Boot

Published on 2024.02.21

Introduction

In modern web development, it is common to secure APIs using bearer token authentication. When implementing this authentication mechanism in a Java Spring Boot application, extracting the bearer token from the request header is an essential step. In this tutorial, we will walk through the process of extracting the bearer token from the request header using Java Spring Boot.

Steps to Extract Bearer Token

  1. Create a new Java Spring Boot project

First, let's create a new Java Spring Boot project. You can use the Spring Initializr (https://start.spring.io/) to generate the project structure with the necessary dependencies.

  1. Implement a custom filter

In order to extract the bearer token from the request headers, we need to implement a custom filter. Create a new class, TokenFilter, and extend the OncePerRequestFilter class provided by Spring Security.

public class TokenFilter extends OncePerRequestFilter {

   @Override
   protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
       String bearerToken = request.getHeader("Authorization");

       // Extract the token
       if (bearerToken != null && bearerToken.startsWith("Bearer ")) {
           String token = bearerToken.substring(7);
           // Do something with the token
       }

       filterChain.doFilter(request, response);
   }

}
  1. Register the filter in the Spring Boot application

Next, we need to register the custom filter in the Spring Boot application. Open the main class of your application and add the @ServletComponentScan annotation at the package level to enable scanning for servlet components.

@SpringBootApplication
@ServletComponentScan
public class SpringBootApp {

   public static void main(String[] args) {
       SpringApplication.run(SpringBootApp.class, args);
   }

}
  1. Test the extraction of the bearer token

Now it's time to test the extraction of the bearer token. Start your Spring Boot application and send a request to an endpoint that requires bearer token authentication. You can use tools like Postman or cURL to send requests with the Authorization header set to a valid bearer token.

  1. Handle the extracted bearer token

Once you have successfully extracted the bearer token from the request header, you can handle it according to your application's requirements. You might want to validate the token, store it for future use, or retrieve user information associated with the token.

Conclusion

In this tutorial, we have learned how to extract the bearer token from the request header in a Java Spring Boot application. By following the step-by-step guide, you can easily implement this functionality in your own projects. Remember to handle the extracted bearer token securely and according to your specific authentication requirements.