在apache官网的commons里面有实现库
Commons FileUpload

The Commons FileUpload package makes it easy to add        robust, high-performance, file upload capability to your servlets and        web applications.

FileUpload parses HTTP requests which conform to        RFC 1867,        "Form-based File Upload in HTML". That is, if an HTTP request is        submitted using the POST method, and with a content type of        "multipart/form-data", then FileUpload can parse that request, and        make the results available in a manner easily used by the caller.

Starting with version 1.3, FileUpload handles        RFC 2047 encoded header values.

The simplest way to send a multipart/form-data request to a server is via a web form, i.e.