Servlet过滤器

用用户请求进行统一认证(如：限制IP、不允许黑名单中用户访问)

对用户请求进行记录、审核(如：写入日志等)

对用户发送的数据进行过滤或替换(如：过滤不良信息等)

转换图像格式

对响应内容进行压缩，减少传输量

对请求、响应内容进行加密、解密操作-Servlet Filters are used to a user request for a unified authentication (such as: restrictions on IP, the blacklist does not allow users to access) to a user request records, audits (such as: write to the log, etc.) to send the data to the user to filter or replace (for example: Filter bad information, etc.) convert image formats compress the response content to reduce the transmission rate on request, to respond to the content encryption, decryption operations