<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
    
    list<fileitem> items = upload.parserequest(request);// 解析form中的所有请求字段，并保存在item中
    iterator<fileitem> 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);
 }
 
}