Spring MVC 提供文件下载的控制器

DownloadController.java

@RequestMapping(value = "/download/{filename:.+}", method = RequestMethod.GET)
public void download(@PathVariable("filename") String filename,HttpServletRequest request ,HttpServletResponse response){
    try {
        File file=new File(request.getSession().getServletContext().getRealPath("/download/"+filename));
        response.setCharacterEncoding("utf-8");
        response.setContentType("multipart/form-data");
        response.setHeader("Content-Disposition", "attachment;filename="+ filename);
        response.setHeader("Content-Length", "" + file.length());
        //System.out.println(file.getAbsolutePath());
        
        InputStream in = new BufferedInputStream(new FileInputStream(file));
        OutputStream out=response.getOutputStream();
        byte[] b=new byte[1024];
        int length;
        while((length=in.read(b)) != -1){
            out.write(b, 0, length);
        }
        in.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

{filename:.+} 这个表达式是为了避免文件名中有"."符号的时候，Spring MVC取不到点后面的扩展名。参考：http://stackoverflow.com/questions/16332092/spring-mvc-pathvariable-with-dot-is-getting-truncated ，
http://stackoverflow.com/questions/3526523/spring-mvc-pathvariable-getting-truncated，
http://blog.csdn.net/milife2013/article/details/8059535

中文文件名未测试。

How To Download File From Website- Java / Jsp
http://www.mkyong.com/java/how-to-download-file-from-website-java-jsp/

我想问下 你下载的文件是放在 download 这个文件夹里麽？ 这个文件夹是建立在项目下哪里啊？求解。谢谢