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>