利用javaweb如何實(shí)現(xiàn)一個(gè)文件上傳功能

發(fā)布時(shí)間：2020-11-16 16:22:26 來源：億速云閱讀：126 作者：Leah 欄目：編程語(yǔ)言

利用javaweb如何實(shí)現(xiàn)一個(gè)文件上傳功能？針對(duì)這個(gè)問題，這篇文章詳細(xì)介紹了相對(duì)應(yīng)的分析和解答，希望可以幫助更多想解決這個(gè)問題的小伙伴找到更簡(jiǎn)單易行的方法。

具體內(nèi)容如下

文件上傳示例

注意：jsp頁(yè)面編碼為"UTF-8"

文件上傳的必要條件

1.form表單，必須為POST方式提交

2.enctype="multipart/form-data"

3.必須有<input type="file" />

前端jsp頁(yè)面

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
 <head>
 <base href="<%=basePath%>" rel="external nofollow" >
 
 <title>My JSP 'index.jsp' starting page</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" rel="external nofollow" >
 -->
 </head>
 <script type="text/javascript">
  function addFile(){
   var div1=document.getElementById("div1");
   div1.innerHTML+="<div><input type='file' /><input type='button' value='刪除' onclick='deleteFile(this)' /> <br/></div>";
  
  }
  function deleteFile(div){
   //他的爺爺刪除他的爸爸
   div.parentNode.parentNode.removeChild(div.parentNode);
  
  }
 </script>
 <body>
  <form action="${pageContext.request.contextPath }/servlet/upLoadServlet" method="post" enctype="multipart/form-data">
  文件的描述：<input type="text" name ="description" /><br/>
  <div id="div1">
   <div>
   <input type="file" name ="file" /><input type="button" value="添加" onclick="addFile()" /><br/>
   </div>   
  </div> 
   <input type="submit" />
  </form>
 </body>
</html>

實(shí)現(xiàn)文件上傳的servlet

package com.learning.servlet;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List;
import java.util.UUID;

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 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;
import org.apache.commons.io.FilenameUtils;

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

 /**
  * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
  */
 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  doGet(request, response);
 }

 /**
  * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
  */
 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
   
  
  //文件上傳
  //判斷是否支持文件上傳
  boolean isMultipartContent = ServletFileUpload
    .isMultipartContent(request);
  if (!isMultipartContent) {
   throw new RuntimeException("不支持");
  }
  
  // 創(chuàng)建一個(gè)DiskFileItemfactory工廠類
  DiskFileItemFactory diskFileItemFactory=new DiskFileItemFactory();
  // 創(chuàng)建一個(gè)ServletFileUpload核心對(duì)象
  ServletFileUpload fileUpload=new ServletFileUpload(diskFileItemFactory);
  //設(shè)置中文亂碼
  fileUpload.setHeaderEncoding("UTF-8");
  //設(shè)置一個(gè)文件大小
  fileUpload.setFileSizeMax(1024*1024*3); //大小為3M
  //設(shè)置總文件大小
  //fileUpload.setSizeMax(1024*1024*10);//大小為10M
  
  try {
   //fileload解析request請(qǐng)求，返回list<FileItem>集合
   List<FileItem> fileItems = fileUpload.parseRequest(request);
   for (FileItem fileItem : fileItems) {
    if (fileItem.isFormField()) {
     //是文本域 (處理文本域的函數(shù))
     processFormField(fileItem);
    }else {
     //文件域 (處理文件域的函數(shù))
     processUpLoadField1(fileItem);
    }
   }
   
  } catch (FileUploadException e) {
   e.printStackTrace();
  }
  
  
 }

 /**
  * @param fileItem
  * 
  */
 private void processUpLoadField1(FileItem fileItem) {
  
  try {
   //獲得文件讀取流
   InputStream inputStream = fileItem.getInputStream();
   
   //獲得文件名
   String fileName = fileItem.getName();
   
   //對(duì)文件名處理
   if (fileName!=null) {
    fileName.substring(fileName.lastIndexOf(File.separator)+1);
    
   }else {
    throw new RuntimeException("文件名不存在");
   }
   
   //對(duì)文件名重復(fù)處理
//   fileName=new String(fileName.getBytes("ISO-8859-1"),"UTF-8");
   fileName=UUID.randomUUID()+"_"+fileName;
   
   //日期分類
   SimpleDateFormat simpleDateFormat=new SimpleDateFormat("yyyy-MM-dd");
   String date = simpleDateFormat.format(new Date());
   //創(chuàng)建目錄
   File parent=new File(this.getServletContext().getRealPath("/WEB-INF/upload/"+date));
   if (!parent.exists()) {
    parent.mkdirs();
   }
   
   //上傳文件
   fileItem.write(new File(parent, fileName));
   //刪除臨時(shí)文件（如果上傳文件過大，會(huì)產(chǎn)生.tmp的臨時(shí)文件）
   fileItem.delete();
   
  } catch (IOException e) {
   System.out.println("上傳失敗");
   e.printStackTrace();
  } catch (Exception e) {
   
  }
  
  
  
 }

 /**
  * @param fileItem
  */
 //文件域
 private void processUpLoadField(FileItem fileItem) {
   
  try {
   //獲得文件輸入流
   InputStream inputStream = fileItem.getInputStream();
   
   //獲得是文件名字
   String filename = fileItem.getName();
   //對(duì)文件名字處理
   if (filename!=null) {
//    filename.substring(filename.lastIndexOf(File.separator)+1);
    filename = FilenameUtils.getName(filename);
   }
   
   //獲得路徑，創(chuàng)建目錄來存放文件
   String realPath = this.getServletContext().getRealPath("/WEB-INF/load");
   
   File storeDirectory=new File(realPath);//既代表文件又代表目錄
   //創(chuàng)建指定目錄
   if (!storeDirectory.exists()) {
    storeDirectory.mkdirs();
   }
   //防止文件名一樣
   filename=UUID.randomUUID()+"_"+filename;
   //目錄打散 防止同一目錄文件下文件太多，不好查找
   
   //按照日期分類存放上傳的文件
   //storeDirectory = makeChildDirectory(storeDirectory);
   
   //多級(jí)目錄存放上傳的文件
   storeDirectory = makeChildDirectory(storeDirectory,filename);
   
   FileOutputStream fileOutputStream=new FileOutputStream(new File(storeDirectory, filename));
   //讀取文件，輸出到指定的目錄中
   int len=1;
   byte[] b=new byte[1024];
   while((len=inputStream.read(b))!=-1){
    fileOutputStream.write(b, 0, len);
   }
   //關(guān)閉流
   fileOutputStream.close();
   inputStream.close(); 
   
  } catch (IOException e) {
   e.printStackTrace();
  } 
 }
 //按照日期來分類
 private File makeChildDirectory(File storeDirectory) {
  SimpleDateFormat simpleDateFormat=new SimpleDateFormat("yyyy-MM-dd");
  String date = simpleDateFormat.format(new Date());
  //創(chuàng)建目錄
  File childDirectory=new File(storeDirectory, date);
  if (!childDirectory.exists()) {
   childDirectory.mkdirs();
  }
  return childDirectory;
 } 
 //多級(jí)目錄
 private File makeChildDirectory(File storeDirectory, String filename) {
  filename=filename.replaceAll("-", ""); 
  File childDirectory =new File(storeDirectory, filename.charAt(0)+File.separator+filename.charAt(1));
  if (!childDirectory.exists()) {
   childDirectory.mkdirs();  
  }
  return childDirectory;
 }
 //文本域
 private void processFormField(FileItem fileItem) {
  //對(duì)于文本域的中文亂碼，可以用new String()方式解決
   try {
    String fieldName = fileItem.getFieldName();//表單中字段名name，如description
    String fieldValue = fileItem.getString("UTF-8");//description中value
//    fieldValue=new String(fieldValue.getBytes("ISO-8859-1"),"UTF-8");
    System.out.println(fieldName +":"+fieldValue);
   } catch (UnsupportedEncodingException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
   
 }

}

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