Spring Security --- Custom Filter

• Introduction
• Any Spring web application is essentially just a servlet
• Security Filter filters every incoming HTTP request before the HTTP request reaches your Controller
• Filter request filter can help filter HttpServletRequest request and HttpServletResponse response
• In the custom Filter filter, the request can be filtered, and the return can also be processed accordingly, and the custom business logic processing can be realized in the method
• What Spring Security itself does is to register a series of Filters in the Spring container
• When these Filters detect a URL request that meets the conditions, they will perform their defined processing
• Default Filter analysis
• Security itself provides some Filters by default to complete its various functions
• Security's default Filter entry is in the HttpSecurity object
• In the HttpSecurity object, what is actually provided is the configuration class of each default Filter
• Control the configuration of each attribute of the corresponding Filter through the configuration class
• After the configuration is complete, load the Filter into the FilterChain in HttpSecurity
• The following default Filter and its configuration classes are provided in HttpSecurity:

  

• The default Filter is not all loaded when the HttpSecurity object is initialized, but loaded according to user customization
• Add a custom Filter to the custom Spring Security configuration class
• Custom Filter class

  

• Why inherit from the OncePerRequestFilter class
• OncePerRequestFilter is an abstract filter class in Spring Boot. The function of this class is to inherit the implementation and perform filtering only once per request.
• Configure myFilter in the custom spring security configuration class
• The implementation of Filter uses the chain of responsibility pattern in the design pattern
• When adding a custom filter, there are many ways, you can specify to add a custom filter before or after a specified filter, how to implement it depends on the user's own choice
• 1- Inject the bean object of the custom Filter

  

• 2- Add the custom Filter bean object before the user login authentication verification filter in the filter chain

  

• 3-Start the project to see if the Filter is effective, send a random request, and see that the defined myFilter is executed, you can add your own logic implementation in this filter

  

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• Complete configuration class code

  

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