文件上传、下载

来源：互联网发布：淄博seo 编辑：程序博客网时间：2024/06/07 15:29

web.xml

<?xml version="1.0" encoding="UTF-8"?><web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">  <display-name>upload</display-name>  <welcome-file-list>    <welcome-file>index.html</welcome-file>    <welcome-file>index.htm</welcome-file>    <welcome-file>index.jsp</welcome-file>    <welcome-file>default.html</welcome-file>    <welcome-file>default.htm</welcome-file>    <welcome-file>default.jsp</welcome-file>  </welcome-file-list>  <servlet>    <description></description>    <display-name>UploadServlet</display-name>    <servlet-name>UploadServlet</servlet-name>    <servlet-class>com.bjsxt.upload.servlet.UploadServlet</servlet-class>  </servlet>  <servlet-mapping>    <servlet-name>UploadServlet</servlet-name>    <url-pattern>/up</url-pattern>  </servlet-mapping>  <servlet>    <description></description>    <display-name>DownloadServlet</display-name>    <servlet-name>DownloadServlet</servlet-name>    <servlet-class>com.bjsxt.upload.servlet.DownloadServlet</servlet-class>  </servlet>  <servlet-mapping>    <servlet-name>DownloadServlet</servlet-name>    <url-pattern>/download</url-pattern>  </servlet-mapping></web-app>

index.html

<!DOCTYPE html><html><head><meta charset="UTF-8"><title>Insert title here</title></head><body>    <!--         文件上传的要求        1. 表单method必须是post        2. 在表单中需要增加file组件提供选择文件        3. 对于form必须要设置enctype="multipart/form-data"来实现文件上传            application/x-www-form-urlencoded默认代表上传的内容是经过url编码的字符串,这种格式不允许传递二进制数据     -->    <form action="/upload/up" method="post" enctype="multipart/form-data">        <input name="name"/>        <input name="age"/>        <input type="file" name="photo"/>        <input type="file" name="photo1"/>        <input type="submit"/>    </form></body></html>

UploadServlet.java

package com.bjsxt.upload.servlet;import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.PrintWriter;import java.text.SimpleDateFormat;import java.util.Date;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.FileUploadException;import org.apache.commons.fileupload.disk.DiskFileItemFactory;import org.apache.commons.fileupload.servlet.ServletFileUpload;/** * Servlet implementation class UploadServlet */public class UploadServlet extends HttpServlet {    private static final long serialVersionUID = 1L;    /**     * @see HttpServlet#HttpServlet()     */    public UploadServlet() {        super();        // TODO Auto-generated constructor stub    }    /**     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)     */    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        // TODO Auto-generated method stub        //创建文件上传的工厂类,初始化CommonFileUpload        DiskFileItemFactory factory = new DiskFileItemFactory();        //利用Servlet实现文件上传的操作        ServletFileUpload upload = new ServletFileUpload(factory);        try {            //解析请求,返回包含文本与文件所有的信息            List<FileItem> items =  upload.parseRequest(request);            //对获取的每一个选项进行处理            for(FileItem fi : items){                if(fi.isFormField() == true){//判断当前的输入是不是表单的输入项                    System.out.println(fi.getFieldName() + ":" + fi.getString("UTF-8"));                }else{//false的时候就是文件了                    System.out.println(fi.getName());//显示原始的文件名                    InputStream is = fi.getInputStream();//获取文件的上传流                    //文件名重名时，后上传的会把先上传的文件给覆盖掉，为了解决这种问题，采取重命名的方法解决（一班采用时间的方式比较多）                                                                                             SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMddHHmmssSSS");                    //进行格式化输出，将系统的时间处理一下，处理好了之后，会获取文件名fileName                    String fileName = sdf.format(new Date());                    //获取原始文件的扩展名（后缀）     substring截取                    String suffix = fi.getName().substring(fi.getName().lastIndexOf("."));                    //把这个流写入到目标的文件里                    FileOutputStream fos = new FileOutputStream("c:/upload/" + fileName + suffix);                    //读文件，两个参数len  , bs                    int len = 0;                    byte[] bs = new byte[1024];//每次读一个字节                    while((len=is.read(bs)) != -1){//读取  ！= -1  表示还有数据                        fos.write(bs , 0 ,len);//将读到的数据写入                    }                    fos.close();                    is.close();                    response.setContentType("text/html;charset=utf-8");                    //进行输出，将文件夹下的目录列出来                    PrintWriter out = response.getWriter();                    //拿到C：盘文件夹下的所有文件                    File uploadDir = new File("c:/upload");                    //拿到c：盘所有文件，返回一个数组                    File[] imgs = uploadDir.listFiles();                    for(File img : imgs){                    //img.getName()文件名                        out.println("<li><a href='/upload/download?name=" + img.getName() + "'>" + img.getName() + "</a></li>");                    }                }            }        } catch (FileUploadException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }}

DownloadServlet.java

package com.bjsxt.upload.servlet;import java.io.File;import java.io.FileInputStream;import java.io.IOException;import java.io.OutputStream;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * Servlet implementation class DownloadServlet */public class DownloadServlet extends HttpServlet {    private static final long serialVersionUID = 1L;    /**     * @see HttpServlet#HttpServlet()     */    public DownloadServlet() {        super();        // TODO Auto-generated constructor stub    }    /**     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)     */    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        //跳转的时候获取它的文件名        String name = request.getParameter("name");        //目标文件         File target = new File("c:/upload/" + name);        response.setContentType("application/x-msdownload");//通知浏览器下载图片而不是打开        //设置下载框默认的文件名        response.setHeader("Content-Disposition", "attachment; filename=" + name);        FileInputStream fis = new FileInputStream(target);//读取原始图片文件        OutputStream os = response.getOutputStream();//获得字节输出流        int len = 0;        byte[] bs = new byte[1024];        //一边读一边写        while((len=fis.read(bs))!= -1){            os.write(bs , 0 ,len);        }        os.flush();        os.close();        fis.close();    }    /**     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)     */    protected void doPost(H## 标题 ##ttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        // TODO Auto-generated method stub        doGet(request, response);    }}

lib

这里写图片描述

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