文件上传和下载

上传和下载需要一些jar包

commons-fileupload-1.3.1.jar

commons-io-2.4.jar

上传界面fileUp.jsp

<h2>文件的上传</h2>
    <form action="fileUp_do.jsp" method="post" enctype="multipart/form-data">
        <input type="file" name="file"><input type="submit" value="提交">
    </form>

上传处理fileUp_do.jsp

<%
    //ServletFileUpload类
    ServletFileUpload upload = new ServletFileUpload(new DiskFileItemFactory());
    //解析request
    List<FileItem> fileItemList = upload.parseRequest(request);
    for (FileItem f : fileItemList) {
        String ext = FilenameUtils.getExtension(f.getName());//获取文件后缀名
        FileOutputStream fos = new FileOutputStream(
                new File("E:\练习\" + System.currentTimeMillis() + "." + ext));
        IOUtils.copy(f.getInputStream(), fos);
        fos.close();
    }
%>

下载界面fileDow.jsp

<h2>文件的下载</h2>
    <%
        File[] files = new File("E:\练习\").listFiles();
        for (File f : files) {
    %>
    <a href="fileDow_do.jsp?filename=<%=f.getName()%>"><%=f.getName()%></a><br/>
    <%
        }
    %>

下载处理fileDow_do.jsp

<%@page import="org.apache.commons.io.IOUtils"%><%@page import="java.io.File"%><%@page import="java.io.FileInputStream"%><%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%><%
    String filename = request.getParameter("filename");
    FileInputStream fis = new FileInputStream(new File("E:\练习\" + filename));
    response.addHeader("Content-Disposition", "attachment;filename=" + filename);
    IOUtils.copy(fis, response.getOutputStream());
    fis.close();
%>

注意：需要删除<%%>和<%%>之间的空格符