Spring5.1以后提供的一个过滤器。将PUT、PATCH、DELETE请求体解析为Servlet请求参数。如果不在web.xml中配置这个过滤器，只有POST请求体可以解析。
Filter that parses form data for HTTP PUT, PATCH, and DELETE requests and exposes it as Servlet request parameters. By default the Servlet spec only requires this for HTTP POST.
原文：https://www.cnblogs.com/A-PP-Z-droplet/p/14339137.html