What is the usage of prehandle in SpringMVC?

In Spring MVC, the preHandle method is a method defined in the HandlerInterceptor interface, used for intercepting and handling requests before they are processed. Its signature is as follows:

Can you handle a request before it is processed?

The preHandle method is called before the request reaches the controller and can be used for pre-processing operations such as authentication, logging, and permission checks. If the preHandle method returns false, the request will be intercepted and will not continue for further processing.

Explanation of the parameters in the preHandle method:

1. request: The HttpServletRequest object of the current request.
2. response: HttpServletResponse object representing the current request.
3. Handler: The object responsible for handling the current request, which is also known as the controller object.

Some operations can be performed as needed in the preHandle method, such as:

1. Perform identity authentication to determine if the user is logged in. If not, redirect to the login page.
2. Record logs to save information such as requested URLs and parameters.
3. Perform authorization checks to determine if the user has permissions to access the current URL. If not, return an error page or handle it appropriately.

It is important to note that the preHandle method is executed in the order of the interceptors. If there are multiple interceptor configurations, then the preHandle method of each interceptor will be called one by one. Only when all preHandle methods return true, the request will continue to be processed further and enter the controller.