使用servlet实现文件上传

 package com.zhanghaobo.fileupload;

 import java.io.File;
 import java.io.IOException;
 import java.util.List;

 import javax.servlet.ServletException;
 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.disk.DiskFileItemFactory;
 import org.apache.commons.fileupload.servlet.ServletFileUpload;

 public class UploadServlet extends HttpServlet {
     @Override
     protected void doPost(HttpServletRequest req, HttpServletResponse resp)
             throws ServletException, IOException {
         DiskFileItemFactory factory=new DiskFileItemFactory();

         String realPath=req.getRealPath("/upload");

         //物理缓存存放地
         factory.setRepository(new File(realPath));

         //设置内存存放大小
         factory.setSizeThreshold(1024*1024);

         ServletFileUpload upload=new ServletFileUpload(factory);
         //FileItem 可以表示文件(file)也可以表示文本域（form item） 有一个isFormField方法判断是否是表单
         try{
             List<FileItem> list=(List<FileItem>)upload.parseRequest(req);
             for(FileItem item:list){
                 String name=item.getFieldName();
                 if(item.isFormField()){
                     String value=item.getString();
                     req.setAttribute(name, value);
                 }else{
                     String value=item.getName();
                     int start=value.lastIndexOf("\\");
                     String fileName=value.substring(start+1);
                     req.setAttribute(name, fileName);
                     //上传文件存放地
                     item.write(new File(realPath,fileName));
                 }
             }
         }catch(Exception e){
             e.printStackTrace();
         }

         req.getRequestDispatcher("showResult.jsp").forward(req, resp);
     }
 }

 public class UploadServlet extends HttpServlet {
     @Override
     protected void doPost(HttpServletRequest req, HttpServletResponse resp)
             throws ServletException, IOException {
         DiskFileItemFactory factory=new DiskFileItemFactory();

         String realPath=req.getRealPath("/upload");

         //物理缓存存放地
         factory.setRepository(new File(realPath));

         //设置内存存放大小
         factory.setSizeThreshold(1024*1024);

         ServletFileUpload upload=new ServletFileUpload(factory);
         //FileItem 可以表示文件(file)也可以表示文本域（form item） 有一个isFormField方法判断是否是表单
         try{
             List<FileItem> list=(List<FileItem>)upload.parseRequest(req);
             for(FileItem item:list){
                 String name=item.getFieldName();
                 if(item.isFormField()){
                     String value=item.getString();
                     req.setAttribute(name, value);
                 }else{
                     String value=item.getName();
                     int start=value.lastIndexOf("\\");
                     String fileName=value.substring(start+1);
                     req.setAttribute(name, fileName);

                     //上传文件存放地
 //                    item.write(new File(realPath,fileName));

                     InputStream is=item.getInputStream();

                     long all=item.getSize();

                     OutputStream os=new FileOutputStream(new File(realPath,fileName));

                     byte[] buffer=new byte[400];

                     int length=0;
                     int l=0;
                     DecimalFormat df=new DecimalFormat("#.00");
                     while(-1!=(length=is.read(buffer))){
                         os.write(buffer,0,length);
                         l+=length;
                         System.out.println("总大小"+all+""+"进度："+(df.format((double)l/all*100))+"%"+"已经读取的大小"+l);
                     }

                     is.close();
                     os.close();

                 }
             }
         }catch(Exception e){
             e.printStackTrace();
         }

         req.getRequestDispatcher("showResult.jsp").forward(req, resp);
     }
 }