What is the function of prehandle in SpringMVC?

The preHandle method in SpringMVC is a method that is called before the request is processed, primarily used for preprocessing the request. Its purpose is as follows:

1. Performing permission verification: User permissions can be verified in the preHandle method to check if the user has permission to access the requested resource. If the user does not have permission, the request can be terminated, and appropriate error information can be returned or a redirect can be performed.
2. Perform login verification: the preHandle method can be used to verify if the user is already logged in. If the user is not logged in, redirect to the login page or return an error message indicating that the user is not logged in.
3. Performing pre-processing of request parameters: In the preHandle method, you can preprocess request parameters, such as parsing and validating parameters. You can modify or validate requests according to actual needs.
4. Recording request logs: the preHandle method can be used to record request logs, such as the URL of the request, request parameters, etc., for later log analysis and debugging. You can choose to record which information based on actual needs.

In short, the preHandle method is called before request handling, allowing for pre-processing such as authorization verification, login validation, parameter handling, and request logging. It serves as a way to customize the processing before the request is handled.