jsp+servlet实现浏览器文件上传和下载功能

最新推荐文章于 2021-02-24 23:14:08 发布

spurs611

最新推荐文章于 2021-02-24 23:14:08 发布

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分类专栏： js

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文件上传功能

jsp页面

<form method="post" action="/ptzy/DailyFileServlet1" enctype="multipart/form-data" οnsubmit="return checkSubmit()">
<div style="text-align: center;"><input id="uploadFile" type="file" name="uploadFile"/>
<input id="uploadFile" type="file" name="uploadFile"/>
<input type="submit" value="上传" style="background-color: #004B97; color: white; font-family: SimSun; font-size: 10px; width: 10%; height: 5%;"/>
</div>
</form>
<div style="text-align: center;margin-top: 50px;font-size:35px;">${message}</div>

使用from表单提交方式

class类

package com.Sysydysjb;

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.HashMap;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

/**
* Servlet implementation class UploadServlet
*/
@WebServlet("/DailyFileServlet")
public class DailyFileServlet extends HttpServlet {
   private static final long serialVersionUID = 1L;

   // 上传文件存储目录
   private static final String UPLOAD_DIRECTORY = "dailyfile";

   // 上传配置
   private static final int MEMORY_THRESHOLD = 1024 * 1024 * 3; // 3MB
   private static final int MAX_FILE_SIZE = 1024 * 1024 * 40; // 40MB
   private static final int MAX_REQUEST_SIZE = 1024 * 1024 * 50; // 50MB

   /**
   * 上传数据及保存文件
   */
   protected void doPost(HttpServletRequest request, HttpServletResponse response )
           throws ServletException, IOException {
       // 检测是否为多媒体上传
       if (!ServletFileUpload.isMultipartContent(request)) {
           // 如果不是则停止
           PrintWriter writer = response.getWriter();
           writer.println("Error: 表单必须包含 enctype=multipart/form-data");
           writer.flush();
           return;
       }
       // 配置上传参数
       DiskFileItemFactory factory = new DiskFileItemFactory();
       // 设置内存临界值 - 超过后将产生临时文件并存储于临时目录中
       factory.setSizeThreshold(MEMORY_THRESHOLD);
       // 设置临时存储目录
       factory.setRepository(new File(System.getProperty("java.io.tmpdir")));
       ServletFileUpload upload = new ServletFileUpload(factory);
       // 设置最大请求值 (包含文件和表单数据)
       upload.setSizeMax(MAX_REQUEST_SIZE);

       // 中文处理
       upload.setHeaderEncoding("UTF-8");
//session中获取上传者信息
       HttpSession session = request.getSession();
       HashMap<String,String> usermap = (HashMap)session.getAttribute("USER_INFO");

       // 构造临时路径来存储上传的文件
       // 这个路径相对当前应用的目录
       String uploadPath = request.getServletContext().getRealPath("./") + File.separator + UPLOAD_DIRECTORY;
       // 如果目录不存在则创建
       File uploadDir = new File(uploadPath);
       if (!uploadDir.exists()) {
           uploadDir.mkdir();
       }

       try {
           // 解析请求的内容提取文件数据
           @SuppressWarnings("unchecked")
           List<FileItem> formItems = upload.parseRequest(request);

           if (formItems != null && formItems.size() > 0) {
               // 迭代表单数据
               for (FileItem item : formItems) {
                   // 处理不在表单中的字段
                   if (!item.isFormField()) {
                       String fileName = new File(item.getName()).getName();
                       String filePath = uploadPath + File.separator + fileName; // 在控制台输出文件的上传路径
                       File storeFile = new File(filePath);
                       // 保存文件到硬盘
                       item.write(storeFile);

DailyFileClass df = new DailyFileClass();
                       int num = df.SaveFileName(fileName, name);
                       if (num > 0) {
                           request.setAttribute("message", "文件上传成功！");
                       } else {
                           request.setAttribute("message", "文件上传失败！请核对文件是否选择正确！");
                       }
                   }
               }
           }
       } catch (Exception ex) {
           request.setAttribute("message", "错误信息: " + ex.getMessage());
       }
       // 跳转到 message.jsp
       request.getServletContext().getRequestDispatcher("/dzappjsps/jsp/dailyfile.jsp").forward(request, response);
   }

   @Override
   protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
       //System.out.println("1这是get方法。。。。。。。。。。。。");
   }
}

到这一步，我们就可以将文件上传到服务器指定位置，并将文件名保存在数据库中，以便于下载时方便使用。

数据库中的数据为：

文件下载功能

jsp页面

<a href="/ptzy/DailyFileDown1?filename=1">文件名</a>

将文件转化为以上格式，可以在class中完成，将其传入到jsp页面。其中，ptzy为项目名称，filename=1为当前文件

class类

package com.Sysydysjb;

import java.io.FileInputStream;
import java.io.IOException;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import ydysz.tools.DownLoadUtils;
@WebServlet("/DailyFileDown")
public class DailyFileDown extends HttpServlet {
   private static final long serialVersionUID = 1L;

   protected void doPost(HttpServletRequest request, HttpServletResponse response)
                       throws ServletException, IOException {
       request.setCharacterEncoding("utf-8");
   //1.获取请求参数，即文件名称
   String filenameid = request.getParameter("filename");

           String filename = new DailyFileClass().getFileNameByID(filenameid); //根据文件编号得到文件名称

   //2.使用字节输入流加载文件进内存
   //2.1找到文件真实（服务器）路径
   ServletContext servletContext = this.getServletContext();
   String realPath = servletContext.getRealPath("/dailyfile/" + filename);

   System.out.println("文件路径=="+realPath);
   //2.2用字节流关联
   FileInputStream fis = new FileInputStream(realPath);//输入流

   //3.设置response的响应头,起到的作用是跳出让下载保存
   //3.1设置响应头类型 content-type
   String mimeType = servletContext.getMimeType(filename);//获取文件的mime类型
   response.setHeader("content-type",mimeType);

   //解决中文乱码问题
   //1.获取user-agent请求头
   String agent = request.getHeader("user-agent");

   //2.使用工具类方法编码文件名即可
   filename = DownLoadUtils.getFileName(agent, filename);

   //3.2设置响应头打开方式 content-disposition 千万不能写错
   response.setHeader("content-disposition", "attachment;filename="+ filename);

   //4.将输入流的数据写出到输出流中
   ServletOutputStream sos = response.getOutputStream();//首先需要一个输出流
   byte[] buff = new byte[1024 * 8];//其次需要一个字节数组作为缓冲区
   int len = 0; //代表读到的字节的个数
   while ((len = fis.read(buff))!= -1){//把输入流中的字节读到缓冲区，并且把读到的个数赋值给len，如果没有读取到文件的末尾
   sos.write(buff, 0, len);//输出流不停的往外写，因为是字节流，所以不用刷新。这里掌握不充分，知识点都不记得了
   }
   fis.close();
   }

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

工具类

package ydysz.tools;

import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;

import sun.misc.BASE64Encoder;

/**
* 下载方式
* @author
*/
public class DownLoadUtils {

public static String getFileName(String agent, String filename) throws UnsupportedEncodingException {
if (agent.contains("MSIE")) {
// IE浏览器
filename = URLEncoder.encode(filename, "utf-8");
filename = filename.replace("+", " ");
} else if (agent.contains("Firefox")) {
// 火狐浏览器
BASE64Encoder base64Encoder = new BASE64Encoder();
filename = "=?utf-8?B?" + base64Encoder.encode(filename.getBytes("utf-8")) + "?=";
} else {
// 其它浏览器
filename = URLEncoder.encode(filename, "utf-8");
}
return filename;
}
}

web.xml配置

<servlet>
<display-name>DailyFileServlet</display-name>
<servlet-name>DailyFileServlet</servlet-name>
<servlet-class>com.Sysydysjb.DailyFileServlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>DailyFileServlet</servlet-name>
<url-pattern>/DailyFileServlet1</url-pattern>
</servlet-mapping>

<servlet>
<display-name>DailyFileDown</display-name>
<servlet-name>DailyFileDown</servlet-name>
<servlet-class>com.Sysydysjb.DailyFileDown</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>DailyFileDown</servlet-name>
<url-pattern>/DailyFileDown1</url-pattern>
</servlet-mapping>