jsp+servlet实现文件上传下载

时间：2023-03-08 16:53:36

相关素材下载

01.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>

<!DOCTYPE HTML>

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>Jsp+Servlet实现文件上传下载</title>

<link rel="stylesheet" type="text/css" href="<%=request.getContextPath() %>/css/common.css" />

<script type="text/javascript" src="<%=request.getContextPath() %>/js/jquery-1.11.1.js"></script>

<script type="text/javascript">

  $(function(){

      $(".thumbs a").click(function(){

          var largePath = $(this).attr("href");

          var largeAlt = $(this).attr("title");

          $("#largeImg").attr({

              src:largePath,

              alt:largeAlt

          });

          return false;

      });

      /* $("#myfile").change(function(){

          $("#previewImg").attr("src", "file:///D:/images/" + $("#myfile").val());

      }); */

      var la = $("large");

      la.hide();

      $("#previewImg").mousemove(function(e) {

          alert('<img src="' + this.src + '"/>');

          la.css({

              top:e.pageY,

              left:e.pageX

          }).html('<img src="' + this.src + '"/>').show();

      }).mouseout(function() {

          la.hide();

      });

  });

  /*js实现*/

  /*function showPreview(obj) {

      var str = obj.value;

      var a = document.getElementById("myfile").value;

      alert(a);

      console.log(str);

      var divImg = document.getElementById("previewImg");

      divImg.innerHTML = "<img src='" + str + "'/>";

  }*/

  function showPreview(obj) {

      var pic = document.getElementById("previewImg");

      var file = obj;

      if (window.FileReader) {

          oFReader = new FileReader();

          oFReader.readAsDataURL(file.files[0]);

          oFReader.onload = function (oFREvent) {pic.src = oFREvent.target.result;};

      }

  }

</script>

</head>

<body>

<!--

    <form action="">

           请选择文件：<input type="file" id="myfile" name="myfile" onchange="showPreview(this)"/>

        <div id="previewImg">

        </div>

    </form>

     -->

     <img id="previewImg" alt="" src="<%=request.getContextPath() %>/images/preview.jpg" width="80" height="80"/>

     <form action="<%=request.getContextPath() %>/uploadServlet" method="post" enctype="multipart/form-data">

           请选择文件：<input type="file" id="myfile" name="myfile" accept="image/*" onchange="showPreview(this)" />

      <input type="submit" value="提交" />${result}

    </form>

    <a href="<%=request.getContextPath() %>/downloadServlet?filename=1.txt">1.txt</a>&nbsp;&nbsp;${errorResult}

     <div id="large"></div>

    <hr>

    <h2>图片预览</h2>

    <p>

        <img id="largeImg" alt="Large Image" src="<%=request.getContextPath() %>/images/img1-lg.jpg" />

    </p>

    <p class="thumbs">

        <a href="<%=request.getContextPath() %>/images/img2-thumb.jpg" title="Image2"><img src="<%=request.getContextPath() %>/images/img2-thumb.jpg" /></a>

        <a href="<%=request.getContextPath() %>/images/img3-thumb.jpg" title="Image3"><img src="<%=request.getContextPath() %>/images/img3-thumb.jpg" /></a>

        <a href="<%=request.getContextPath() %>/images/img4-thumb.jpg" title="Image4"><img src="<%=request.getContextPath() %>/images/img4-thumb.jpg" /></a>

        <a href="<%=request.getContextPath() %>/images/img5-thumb.jpg" title="Image5"><img src="<%=request.getContextPath() %>/images/img5-thumb.jpg" /></a>

        <a href="<%=request.getContextPath() %>/images/img6-thumb.jpg" title="Image6"><img src="<%=request.getContextPath() %>/images/img6-thumb.jpg" /></a>

    </p>

</body>

</html>

文件上传UploadServlet.java

import java.io.File;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.RandomAccessFile;

import javax.servlet.RequestDispatcher;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public class UploadServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    @Override

    protected void doGet(HttpServletRequest req, HttpServletResponse resp)

            throws ServletException, IOException {

        this.doPost(req, resp);

    }

    @Override

    protected void doPost(HttpServletRequest req, HttpServletResponse resp)

            throws ServletException, IOException {

        InputStream fileSource = req.getInputStream();

        File tempFile = new File("D:/tempFile");

        FileOutputStream outputStream = new FileOutputStream(tempFile);

        byte[] b = new byte[1024];

        int n;

        while ((n = fileSource.read(b)) != -1) {

            outputStream.write(b, 0, n);

        }

        outputStream.close();

        fileSource.close();

        // 获取上传文件名称

        RandomAccessFile randomFile = new RandomAccessFile(tempFile, "r");

        randomFile.readLine();

        String str = randomFile.readLine();

        int beginIndex = str.lastIndexOf("=") + 2;

        int endIndex = str.lastIndexOf("\"");

        String fileName = str.substring(beginIndex, endIndex);

        System.out.println(fileName);

        // 重新定位文件指针到文件头

        randomFile.seek(0);

        long startPosition = 0;

        int i = 1;

        // 获取文件内容

        while ((n = randomFile.readByte()) != -1 && i <= 4) {

            if (n == '\n') {

                startPosition = randomFile.getFilePointer();

                i++;

            }

        }

        startPosition = startPosition - 1;

        // 获取文件内容结束位置

        randomFile.seek(randomFile.length());

        long endPosition = randomFile.getFilePointer();

        int j = 1;

        while (endPosition >= 0 && j <= 2) {

            endPosition--;

            randomFile.seek(endPosition);

            if (randomFile.readByte() == '\n') {

                j++;

            }

        }

//        endPosition = endPosition - 1;

        // 设置保存上传文件的路径

        String realPath = getServletContext().getRealPath("/") + "images";

        File fileupload = new File(realPath);

        if (!fileupload.exists()) {

            fileupload.mkdir();

        }

        File saveFile = new File(realPath, fileName);

        RandomAccessFile randomAccessFile = new RandomAccessFile(saveFile, "rw");

        // 从临时文件当中读取文件内容（根据起止位置获取）

        randomFile.seek(startPosition);

        randomFile.readLine();

        while(startPosition < endPosition) {

            randomAccessFile.write(randomFile.readByte());

            startPosition = randomFile.getFilePointer();

        }

        // 关闭输入输出流,删除临时文件

        randomAccessFile.close();

        randomFile.close();

        tempFile.delete();

        req.setAttribute("result", "上传成功！");

        RequestDispatcher dispatcher = req.getRequestDispatcher("jsp/01.jsp");

        dispatcher.forward(req, resp);

    }

}

文件下载DownloadServlet.java

import java.io.File;

import java.io.FileInputStream;

import java.io.IOException;

import java.io.InputStream;

import javax.servlet.RequestDispatcher;

import javax.servlet.ServletException;

import javax.servlet.ServletOutputStream;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public class DownloadServlet extends HttpServlet{

    private static final long serialVersionUID = 1L;

    @Override

    protected void doGet(HttpServletRequest req, HttpServletResponse resp)

            throws ServletException, IOException {

        // 获取文件下载路径

        String path = getServletContext().getRealPath("/") + "images/";

        String fileName = req.getParameter("filename");

        File file = new File(path + fileName);

        if (file.exists()) {

            // 设置相应类型 application/octet-stream

            resp.setContentType("application/x-msdownload");

            // 设置头信息

            resp.setHeader("Content-Disposition", "attachment;filename=\"" + fileName + "\"");

            InputStream inputStream = new FileInputStream(file);

            ServletOutputStream outputStream = resp.getOutputStream();

            byte[] b = new byte[1024];

            int n;

            while((n = inputStream.read(b)) != -1) {

                outputStream.write(b, 0, n);

            }

            // 关闭流，释放资源

            outputStream.close();

            inputStream.close();

        } else {

            req.setAttribute("errorResult", "文件不存在下载失败");

            RequestDispatcher dispatcher = req.getRequestDispatcher("jsp/01.jsp");

            dispatcher.forward(req, resp);

        }

    }

    @Override

    protected void doPost(HttpServletRequest req, HttpServletResponse resp)

            throws ServletException, IOException {

        this.doGet(req, resp);

    }

}

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_3_0.xsd"

    id="WebApp_ID" version="3.0">

    <display-name>scxz</display-name>

    <servlet>

        <servlet-name>UploadServlet</servlet-name>

        <servlet-class>com.lijy.servlet.UploadServlet</servlet-class>

    </servlet>

    <servlet>

        <servlet-name>DowloadServlet</servlet-name>

        <servlet-class>com.lijy.servlet.DownloadServlet</servlet-class>

    </servlet>

    <servlet-mapping>

        <servlet-name>UploadServlet</servlet-name>

        <url-pattern>/uploadServlet</url-pattern>

    </servlet-mapping>

    <servlet-mapping>

        <servlet-name>DowloadServlet</servlet-name>

        <url-pattern>/downloadServlet</url-pattern>

    </servlet-mapping>

    <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>

</web-app>

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