我猜你应该是这个意思：

html:

<form method="post" enctype="multipart/form-data">
<input type="file" />
...
</form>

jsp:

FileItemFactory factory = new DiskFileItemFactory();
ServletFileUpload upload = new ServletFileUpload(factory);
List /* FileItem */ items = upload.parseRequest(request);
try{
    FileWriter fstream = new FileWriter("out.txt");
    BufferedWriter out = new BufferedWriter(fstream);
    out.write(item.get());
    out.close();
    }catch (Exception e){
      System.err.println("Error: " + e.getMessage());
    }