java上传文件

借鉴别人的代码，自己再总结记录一下：

后台：

package com.sitech.easkLog;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

import java.io.InputStream;
import java.util.*;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

/**
 *
 * @author administrator
 */
@SuppressWarnings("unchecked")
public class UpLoad extends HttpServlet {

    /** */
    private static final long serialVersionUID = 1L;

    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=GBK");
        String action = request.getParameter("action");
        if("uploadFile".equals(action)){
            this.uploadFile(request,response);  //上传文件
        }
    }


    public void uploadFile(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=GBK");
        request.setCharacterEncoding("GBK");
        HttpSession session=request.getSession();
        session.setAttribute("progressBar",0);      //定义指定上传进度的Session变量
        String error = "";
        int maxSize=50*1024*1024;        //单个上传文件大小的上限
        DiskFileItemFactory factory = new DiskFileItemFactory();        //基于磁盘文件项目创建一个工厂对象
        ServletFileUpload upload = new ServletFileUpload(factory);  //创建一个新的文件上传对象
        try {
            List items = upload.parseRequest(request);// 解析上传请求
            Iterator itr = items.iterator();// 枚举方法
            while (itr.hasNext()) {
                FileItem item = (FileItem) itr.next();  //获取FileItem对象
                if (!item.isFormField()) {// 判断是否为文件域
                    if (item.getName() != null && !item.getName().equals("")) {// 判断是否选择了文件
                        long upFileSize=item.getSize();     //上传文件的大小
                        String fileName=item.getName();     //获取文件名
                        //System.out.println("上传文件的大小:" + item.getSize());
                        if(upFileSize>maxSize){
                            error="您上传的文件太大，请选择不超过50M的文件";
                            break;
                        }
                        // 此时文件暂存在服务器的内存中
                        File tempFile = new File(fileName);// 构造临时对象
                        String uploadPath = this.getServletContext().getRealPath("/upload");
                        File file = new File(uploadPath,tempFile.getName());   // 获取根目录对应的真实物理路径
                        InputStream is=item.getInputStream();
                        int buffer=1024;     //定义缓冲区的大小
                        int length=0;
                        byte[] b=new byte[buffer];
                        double percent=0;
                        FileOutputStream fos=new FileOutputStream(file);
                        while((length=is.read(b))!=-1){
                            percent+=length/(double)upFileSize*100D;        //计算上传文件的百分比
                            fos.write(b,0,length);                      //向文件输出流写读取的数据
                            session.setAttribute("progressBar",Math.round(percent));    //将上传百分比保存到Session中
                        }
                        fos.close();
                        Thread.sleep(1000);     //线程休眠1秒
                    } else {
                        error="没有选择上传文件！";
                    }
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
            error = "上传文件出现错误：" + e.getMessage();
        }
        if (!"".equals(error)) {
            request.setAttribute("error", error);
            request.getRequestDispatcher("error.jsp").forward(request, response);
        }else {
            request.setAttribute("result", "文件上传成功！");
            request.getRequestDispatcher("upFile_deal.jsp").forward(request, response);
        }
    }
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException,
            IOException {
        processRequest(request, response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException,
            IOException {
        processRequest(request, response);
    }

    @Override
    public String getServletInfo() {
        return "Short description";
    }// </editor-fold>
}

上传jsp页面

<%@ page language="java" pageEncoding="UTF-8"%>
 <!DOCTYPE HTML>
 <html>
 <head>
  <title>文件上传</title>
 </head>
 
 <body>
  <form action="${pageContext.request.contextPath}/servlet/UploadHandleServlet" enctype="multipart/form-data" method="post">
   上传用户：<input type="text" name="username"><br/>
   上传文件1：<input type="file" name="file1"><br/>
   上传文件2：<input type="file" name="file2"><br/>
   <input type="submit" value="提交">
  </form>
 </body>
 </html>

上传成功后：

<%@ page language="java" pageEncoding="UTF-8"%>
 <!DOCTYPE HTML>
 <html>
 <head>
  <title>消息提示</title>
 </head>
 
 <body>
   ${message}
 </body>
 </html>