HttpServletResponse 下载功能的实现

DiskFileItemFactory dfif = new DiskFileItemFactory();//创建硬盘文件项工厂

ServletFileUpload sfu = new ServletFileUpload(dfif);//创建文件组选项

sfu.setHeaderEncoding("utf-8");
sfu.setFileSizeMax(30*1024*1024);//设置上传文件大小

List items = null;
try{
items = sfu.parseRequest(req);
}catch(FileUploadException e){
e.printStackTrace();
}
Iterator it = items.iterator();
int i =1;
while(it.hasNext()){

FileItem fileitem = (FileItem)it.next();

ServletOutputStream outputStream = resp.getOutputStream();

resp.setHeader("content-disposition","attachment;filename="+name);

while((ss = value.read())!=-1){
outputStream.write(ss);
}

outputStream.flush();
outputStream.close();

后记：

如果name的命名是中文，需要转码：name = java.net.URLENconder.encode(name,"utf-8")

方法二

代理方式：resp.setContentType("application/x-msdownload");