springmvc 文件下载

基于spring4 mvc 构建本项目。

• spring4 提供对象管理功能。
• springmvc 提供mvc框架

原始英文写得比较好，copy如下：
Downloading a file is quite simple and involves following steps.

• Create an InputStream to the file to be downloaded.
  Find MIME type of the content of downloaded file.
  – can be of application/pdf, text/html,application/xml,image/png, ..others.
  　Set Content-Type in response(HttpServletResponse) with MIME type found above.
  response.setContentType(mimeType);
  　Set Content length in response with MIME type found above.
  response.setContentLength(file.getLength());//length in bytes

• Set Content-Disposition HEADER in response.
  response.setHeader(“Content-Disposition”, “attachment; filename=” + fileName); //With ‘attachement’ File will be downloaded as is. May show a ‘Save as’ dialog based on browser setting.
  response.setHeader(“Content-Disposition”, “inline; filename=” + fileName);//With ‘inline’ browser will try to display content right into broswer for certain contents(imgages,PDF,text,..). For other content types, file will be download directly.

• Copy bytes from InputStream to OutputStream of response.

• Once copying done, close input & output stream.

本项目没有xml配置文件，全部以注解的方式，进行配置注入。