JSP实现文件上传功能

form action="UploadServlet" method="post" enctype="multipart/form-data">
 学号:input type="text" name="sno"/>br/>
 姓名:input type="text" name="sname"/>br/>
 上传照片:input type="file" name="spicture"/>br/>
 input type="submit" value="注册"/>
/form>

package webtest;
 
import java.io.File;
import java.io.IOException;
import java.util.Iterator;
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.HttpServletResponse;
 
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;
 
/**
 * 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");// 请求编码处理，传输时
  response.setCharacterEncoding("utf-8");// 响应编码处理,传输时
  response.setContentType("utf-8");// 响应编码处理，显示时
  boolean isMultipart = ServletFileUpload.isMultipartContent(request);// 判断是否有entype="multipart/form-data"部分
  if (isMultipart) {
   try {
    FileItemFactory factory = new DiskFileItemFactory();
    ServletFileUpload upload = new ServletFileUpload(factory);
    
    //设置上传时的内存缓冲区大小，超出时写入临时文件  10kb
    ((DiskFileItemFactory) factory).setSizeThreshold(10240);//单位byte
    //设置临时文件目录，防止系统空间不足
    ((DiskFileItemFactory) factory).setRepository(new File(request.getSession().getServletContext().getRealPath("Uploadtemp")));//动态获取Uploadtemp文件夹位于该项目中的位置
    //控制上传单个文件的最大值 20kb
    upload.setSizeMax(20480);//单位byte
    
    ListFileItem> items = upload.parseRequest(request);// 解析form中的所有请求字段，并保存在item中
    IteratorFileItem> iter = items.iterator();
 
    while (iter.hasNext()) {
     // 解析时无顺序，因此需根据名字查找
     FileItem item = iter.next();
     if (item.isFormField()) {//非文件数据
      String itemName = item.getFieldName();//获取非文件的范围数据名
      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("其他字段...");
      }
 
     } else {//文件上传
      String fileName = item.getName();//获取文件范围数据。路径及其名称
      //判断文件类型
      String ext = fileName.substring(fileName.indexOf(".")+1);
      if(!(ext.equals("png")||ext.equals("gif")||ext.equals("jpg"))) {
       System.out.println("仅支持png.gif,jpg类型文件");
       return ;
      }
      String path = request.getSession().getServletContext().getRealPath("Upload");//动态获取Upload文件夹位于该项目中的位置
      File file = new File(path,fileName);
      item.write(file);//定义上传路径，多为服务器路径
      System.out.println(fileName+"上传成功");
     }
     item.delete();//删除临时目录的文件
    }
   } 
   catch(FileUploadBase.SizeLimitExceededException e) {
    System.out.println("最大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);
 }
 
}