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);
    }
}