java 文件的上传和下载

主要介绍使用 smartupload.jar 包中的方法对文件的上传和下载。上传时文件是存放在服务器中，我用的是tamcat。

首先建立一个servlet 类，对文件的操作

 package com.dkt.servlet;

 import java.io.File;
 import java.io.IOException;
 import java.sql.SQLException;
 import java.util.ArrayList;

 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;

 import org.lxh.smart.Files;
 import org.lxh.smart.SmartUpload;
 import org.lxh.smart.SmartUploadException;

 public class FileUpdownLoad extends HttpServlet {

     public void doGet(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {
         doPost(request, response);
     }

     public void doPost(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {

         response.setContentType("text/html");
         request.setCharacterEncoding("GB2312");
         response.setCharacterEncoding("GB2312");
         SmartUpload su = new SmartUpload();

         String op = request.getParameter("op");
         if (("upload").equals(op)) {
             su.initialize(getServletConfig(), request, response);//初始化
             su.setAllowedFilesList("txt,jpg,png,docx,xml,PNG,xlsx");//允许上传的文件类型，区分大小写
             try {
                 su.setDeniedFilesList("html,exe");//不允许上传的文件类型
             } catch (SQLException e) {
                 e.printStackTrace();
             }
             su.setMaxFileSize(5000000);//文件大小

             /*Files files = su.getFiles();
             org.lxh.smart.File file2 = files.getFile(0);
             System.out.println(file2.getFileName());
             for(int i=0;i<files.getCount();i++){
                 org.lxh.smart.File file = files.getFile(i);
                 String fileName = file.getFileName();
                 System.out.println("fileName---->"+fileName);
                 fileName =  new String(fileName.getBytes("ISO-8859-1"),"GB2312");
                 try {
                     file.saveAs(fileName);
                 } catch (SmartUploadException e) {
                     e.printStackTrace();
                 }
             }*/
             try {
                 su.upload();//上传
                 su.save("/smartUpdownload");//上传的路径，在tomcat下的文件夹中
                 System.out.println("上传成功！！！");
             } catch (SmartUploadException e) {
                 e.printStackTrace();
             }
             request.getRequestDispatcher("fileUpDownload.jsp").forward(request, response);
         }else if(("showFiles").equals(op)){
             //得到上传到服务器的文件夹
             String realPath = this.getServletContext().getRealPath("smartUpdownload");
             //得到所有文件的文件名，并显示在页面上
             File file = new File(realPath);
             File[] listFiles = file.listFiles();
             ArrayList<String> list = new ArrayList<String>();
             for (File fi : listFiles) {
                 list.add(fi.getName());//把所有的文件名存入集合
             }
             request.setAttribute("list", list);
             request.getRequestDispatcher("fileUpDownload.jsp").forward(request, response);
         }else if(("download").equals(op)){
             su.initialize(getServletConfig(), request, response);//初始化
             su.setContentDisposition(null);
             String filename1 = request.getParameter("filename");
             String filename = new String(filename1.getBytes("ISO-8859-1"), "GB2312");
             System.out.println(filename);
             try {
                 su.downloadFile("/smartUpdownload/"+filename);
             } catch (SmartUploadException e) {
                 e.printStackTrace();
             }
         }

     }

 }

jsp 内容如下:

这里使用到了  c 标签，所以需要两个jar包  jstl.jar 和   standard-1.1.2.jar

并使用

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %> 导入包

 <%@ page language="java" import="java.util.*" pageEncoding="gb2312"%>
 <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
 <%@page import="org.lxh.smart.SmartUpload"%>
 <%@page import="org.lxh.smart.File"%>
 <%
 String path = request.getContextPath();
 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
 %>

 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
 <html>
   <head>
     <base href="<%=basePath%>">

     <title>My JSP 'fileUpDownload.jsp' starting page</title>

     <meta http-equiv="pragma" content="no-cache">
     <meta http-equiv="cache-control" content="no-cache">
     <meta http-equiv="expires" content="0">
     <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
     <meta http-equiv="description" content="This is my page">
     <!--
     <link rel="stylesheet" type="text/css" href="styles.css">
     -->

   </head>

   <body>
     <form action="FileUpdownLoad?op=upload"  method="post" enctype="multipart/form-data" >
             <input  type="file" name="file1" value="上传的文件">
             <input type="submit" value="上传">
     </form>
     <hr/>
     <a href = "FileUpdownLoad?op=showFiles">显示下载的文件目录</a><br/>
     <c:forEach  items="${list}" var="filename">
         <a href="FileUpdownLoad?op=download&filename=${filename }">下载文件：${filename }</a><br/>
     </c:forEach>

     <a href="ImageServlet">显示水印图片</a>
   </body>
 </html>