ファイルアップロード機能のJSP実装

<form action="UploadServlet" method="post" enctype="multipart/form-data">
 Academic number:<input type="text" name="sno"/><br/>
 Name:<input type="text" name="sname"/><br/>
 Upload a photo:<input type="file" name="spicture"/><br/>
 <input type="submit" value="register"/>
</form>

package webtest;
 
import java.io.File;
import java.io.IOException;
import java.util;
import java.util.List;
 
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http;
 
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileItemFactory;
import org.apache.commons.fileupload.FileUploadBase;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
 
ServletFileUpload; /**
 * Servlet implementation class UploadServlet
 */
@WebServlet("/UploadServlet")
public class UploadServlet extends HttpServlet {
 private static final long serialVersionUID = 1L;
 
 protected void doGet(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  request.setCharacterEncoding("utf-8");// request encoding processing, when transferring
  response.setCharacterEncoding("utf-8");// response encoding, when transferring
  response.setContentType("utf-8");// response encoding, when displaying
  boolean isMultipart = ServletFileUpload.isMultipartContent(request);// determine whether there is entype="multipart/form-data" part
  if (isMultipart) {
   try {
    FileItemFactory factory = new DiskFileItemFactory();
    ServletFileUpload upload = new ServletFileUpload(factory);
    
    // set the size of the memory buffer when uploading, and write a temporary file if it exceeds 10kb
    ((DiskFileItemFactory) factory).setSizeThreshold(10240);//unit byte
    //set the temporary file directory to prevent the system from running out of space
    ((DiskFileItemFactory) factory).setRepository(new File(request.getSession().getServletContext().getRealPath("Uploadtemp")) );// dynamically get the location of the Uploadtemp folder in the project
    //control the maximum size of a single file upload 20kb
    upload.setSizeMax(20480);//unit byte
    
    List<FileItem> items = upload.parseRequest(request);// parse all request fields in the form and save them in the items
    Iterator<FileItem> iter = items.iterator();
 
    while (iter.hasNext()) {
     // Parsing is not sequential, so you need to look by name
     FileItem item = iter.next();
     if (item.isFormField()) { // non-file data
      String itemName = item.getFieldName();//Get the name of the non-file range data
      if (itemName.equals("sno")) {
       int sno = -1;
       sno = Integer.parseInt(item.getString("utf-8"));
      }
      else if (itemName.equals("sname")) {
       String sname = null; 
       sname = item.getString("utf-8");
 
      } 
      else {
       System.out.println("Other fields... ");
      }
 
     } else {//File upload
      String fileName = item.getName();//Get the file range data. Path and its name
      //judge the file type
      String ext = fileName.substring(fileName.indexOf(". ") + 1);
      if(! (ext.equals("png")||ext.equals("gif")||ext.equals("jpg"))) {
       System.out.println("Only png.gif,jpg type files are supported");
       return ;
      }
      String path = request.getSession().getServletContext().getRealPath("Upload");// dynamically get the location of the Upload folder in the project
      File file = new File(path,fileName);
      item.write(file);//define the upload path, mostly the server path
      System.out.println(fileName+"Upload successful");
     }
     item.delete();//delete the files in the temporary directory
    }
   } 
   catch(FileUploadBase.SizeLimitExceededException e) {
    System.out.println("Maximum 20KB");
   }
   catch (FileUploadException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   } 
   catch (Exception e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
  }
 }
 
 /**
  * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
  * response)
  */
 protected void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  // TODO Auto-generated method stub
  doGet(request, response);
 }
 
}