스프링 부트에서 doFilter Method 사용방법.

Understanding doFilter method in Spring Boot

As a Spring Boot developer, you might have come across the doFilter method while working with filters. In this blog post, we will dive deeper into the doFilter method and understand its significance in Spring Boot.

What is a Filter in Spring Boot?

A filter in Spring Boot is an object that intercepts incoming HTTP requests and outgoing HTTP responses. It can be used to perform various tasks such as logging, authentication, and authorization. Filters are executed before the request reaches the controller and after the response leaves the controller.

What is the doFilter method?

The doFilter method is a method of the Filter interface. It is called by the container each time a request/response pair is passed through the chain due to a client request for a resource at the end of the chain. The doFilter method takes three parameters:

• ServletRequest request: The request object that is passed to the filter.
• ServletResponse response: The response object that is passed to the filter.
• FilterChain chain: The filter chain that is used to invoke the next filter in the chain.

The doFilter method is responsible for invoking the next filter in the chain or the resource at the end of the chain. If the filter decides to pass the request to the next filter, it calls the doFilter method of the next filter in the chain. If the filter decides to stop processing the request, it can send a response back to the client or throw an exception.

How to implement the doFilter method?

To implement the doFilter method, you need to create a class that implements the Filter interface. Here is an example of a filter that logs incoming requests:

@Component public class LoggingFilter implements Filter {      private static final Logger logger = LoggerFactory.getLogger(LoggingFilter.class);      @Override     public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {         logger.info("Received request: {}", request.getRemoteAddr());         chain.doFilter(request, response);     } } 

In this example, the LoggingFilter class logs the remote address of the incoming request and then passes the request to the next filter in the chain.

Conclusion

In conclusion, the doFilter method is an important method in Spring Boot filters. It is responsible for invoking the next filter in the chain or the resource at the end of the chain. By implementing the doFilter method, you can perform various tasks such as logging, authentication, and authorization. We hope this blog post has helped you understand the doFilter method better.