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java component fileupload file upload demo

  • 2020-05-10 18:11:04
  • OfStack

In our web development, there are many times when you need to upload some files from the machine to the web server.

For example, an BBS system can upload some pictures and documents of the machine to the server when the user USES the system. Then other users can download the files, so we can upload the files ourselves, but it's better to use some of the existing components to help us with this.

Common upload components:

The Apache Commons FileUpload

The JavaZoom UploadBean

jspSmartUpload

FileUpload download address:

http: / / commons. apache. org/fileupload /

Download: commons-fileupload-1.2.2-bin.zip       get: commons-fileupload-1.2.2.jar

http: / / commons. apache. org/io /

commons-io-1.4-bin.zip           commons-io-1.4.jar

upload.jsp

Code; 


<%@ page language="java" contentType="text/html; charset=UTF-8"%>
<html>
<head>
<title>using commons Upload to upload file </title>
</head>
<style>
* { font-family: " Song typeface "; font-size: 14px }
</style>
<body>
<p align="center">  Please select the file you want to upload </p>
<form id="form1" name="form1" method="post" action="servlet/fileServlet" enctype="multipart/form-data">
 <table border="0" align="center">
 <tr>
 <td> From: </td>
 <td>
 <input name="name" type="text" id="name" size="20" ></td>
 </tr> 
 <tr>
 <td> Upload file: </td>
 <td><input name="file" type="file" size="20" ></td>
 </tr> 
 <tr> 
 <td></td><td>
 <input type="submit" name="submit" value=" submit " >
 <input type="reset" name="reset" value=" reset " >
 </td>
 </tr>
 </table>
</form>
</body>
</html>

FileUploadServlet. java code: 


package com.b510.example;

import java.io.File;
import java.io.IOException;
import java.util.*;


import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
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;

/**
 * 
 * @author XHW
 * 
 * @date 2011-7-26
 * 
 */
public class FileUploadServlet extends HttpServlet {

 private static final long serialVersionUID = -7744625344830285257L;
 private ServletContext sc;
 private String savePath;

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

 public void init(ServletConfig config) {
 //  in web.xml Set in the 1 Three initialization parameters 
 savePath = config.getInitParameter("savePath");
 sc = config.getServletContext();
 }
 
 public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 request.setCharacterEncoding("UTF-8");
 DiskFileItemFactory factory = new DiskFileItemFactory();
 ServletFileUpload upload = new ServletFileUpload(factory);
 try {
 List items = upload.parseRequest(request);
 Iterator itr = items.iterator();
 while (itr.hasNext()) {
 FileItem item = (FileItem) itr.next();
 if (item.isFormField()) {
  System.out.println(" Form parameter name :" + item.getFieldName() + " , form parameter values :" + item.getString("UTF-8"));
 } else {
  if (item.getName() != null && !item.getName().equals("")) {
  System.out.println(" Upload file size :" + item.getSize());
  System.out.println(" The type of file to upload :" + item.getContentType());
  // item.getName() Returns the full path name of the uploaded file on the client 
  System.out.println(" The name of the uploaded file :" + item.getName());

  File tempFile = new File(item.getName());

 / / save path of uploaded file 
  File file = new File(sc.getRealPath("/") + savePath, tempFile.getName());
  item.write(file);
  request.setAttribute("upload.message", " Upload file successfully! ");
  }else{
  request.setAttribute("upload.message", " No option to upload files! ");
  }
 }
 }
 }catch(FileUploadException e){
 e.printStackTrace();
 } catch (Exception e) {
 e.printStackTrace();
 request.setAttribute("upload.message", " Failed to upload file! ");
 }
 request.getRequestDispatcher("/uploadResult.jsp").forward(request, response);
 }
}

uploadResult. jsp code: 


<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
 <head>
 
 <title>uploadResult</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>
 ${requestScope['upload.message'] }
 <a href="/upload/uploadFile.jsp"> Upload a file </a>
 </body>
</html>

web.xml

Code: 


<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
 xmlns="http://java.sun.com/xml/ns/javaee" 
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
 xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
 http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
 <servlet>
 <description>This is the description of my J2EE component</description>
 <display-name>This is the display name of my J2EE component</display-name>
 <servlet-name>FileUploadServlet</servlet-name>
 <servlet-class>com.b510.example.FileUploadServlet</servlet-class>

  
 <init-param>
  <param-name>savePath</param-name>
  <param-value>uploads</param-value>
 </init-param>
 </servlet>

 <servlet-mapping>
 <servlet-name>FileUploadServlet</servlet-name>
 <url-pattern>/servlet/fileServlet</url-pattern>
 </servlet-mapping>
 <welcome-file-list>
 <welcome-file>index.jsp</welcome-file>
 <welcome-file>uploadFile.jsp</welcome-file>
 </welcome-file-list>
</web-app>
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