1. Filter
1.1 Definitions
Servlet filters are Java classes that can be used in servlet programming for the following purposes:
- Intercept client requests before they access backend resources.
- These responses are processed before the server's responses are sent back to the client.
1.2 Usage scenarios
In actual application development, we often use filters to do the following things
- Based on certain authorization logic, HTTP requests are filtered to ensure the security of data access. For example: determine whether the source IP of the request is in the system blacklist
- For some encrypted HTTP request data, perform unified decryption to facilitate business processing by back-end resources
- Or filter sensitive words that are often required in our social applications, or use filters to filter out illegal requests that trigger sensitive words
The main features of the filter are: First, it can filter all requests, and second, it can change the data content of the request.