What is the difference between Filter and Interceptor in Spring?

This article brings you what is the difference between Filter and Interceptor in Spring? It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

Interceptor

Main function: intercept user requests and process them, such as determining user login status and authority verification, as long as it targets the Controller Requests are processed through HandlerInterceptor.

Interceptor is divided into two situations. One is to intercept the session. Implement spring's HandlerInterceptor interface and register it in the interception queue of mvc. The preHandle() method is performed before calling Handler. Interception (step 3 in the above picture), postHandle() method is called before the view is rendered (step 5 in the above picture), afterCompletion()The method is executed before returning the corresponding method; the other is to intercept the method, which requires the use of @Aspect annotation to intercept before and after each call to the specified method.

Filter

Main functions: filter character encoding and make some business logic judgments. It is mainly used to preprocess user requests and can also make logical judgments.

Filter will be filtered by the filter before the request enters the servlet container to execute the service() method (step 1 in the picture above). It does not rely on the springmvc framework like Intreceptor, but only needs to rely on servlet . Filter startup is started with the startup of the WEB application. It only needs to be initialized once and can be intercepted in the future.

Filter has the following types:

User authorization Filter: checks user requests and filters illegal user requests according to the request;

Log Filter: records certain special user requests ;

Decoding Filter: Decode requests for non-standard encoding.

The difference between Filter and Interceptor

1. Filter is based on function callback (doFilter() method), while Interceptor is based on Java reflection (AOP idea) .

2. Filter depends on the Servlet container, while Interceptor does not depend on the Servlet container.

3. Filter works on almost all requests, while Interceptor can only work on action requests.

4. Interceptor can access the context of Action and the objects in the value stack, but Filter cannot.

5. In the life cycle of the action, Interceptor can be called multiple times, while Filter can only be called once when the container is initialized.

6. Filter can only operate on request and response, while interceptor can operate on request, response, handler, modelAndView, and exception.

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