javaweb实现文件上传示例代码

时间：2021-05-19

本文实例为大家分享了javaweb文件下载的具体实现代码，供大家参考，具体内容如下

文件上传示例

注意：jsp页面编码为"UTF-8"

文件上传的必要条件

1.form表单，必须为POST方式提交

2.enctype="multipart/form-data"

3.必须有<input type="file" />

前端jsp页面

<%@ 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='删除' onclick='deleteFile(this)' /> <br/></div>"; } function deleteFile(div){ //他的爷爷删除他的爸爸 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>

实现文件上传的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 { //文件上传 //判断是否支持文件上传 boolean isMultipartContent = ServletFileUpload .isMultipartContent(request); if (!isMultipartContent) { throw new RuntimeException("不支持"); } // 创建一个DiskFileItemfactory工厂类 DiskFileItemFactory diskFileItemFactory=new DiskFileItemFactory(); // 创建一个ServletFileUpload核心对象 ServletFileUpload fileUpload=new ServletFileUpload(diskFileItemFactory); //设置中文乱码 fileUpload.setHeaderEncoding("UTF-8"); //设置一个文件大小 fileUpload.setFileSizeMax(1024*1024*3); //大小为3M //设置总文件大小 //fileUpload.setSizeMax(1024*1024*10);//大小为10M try { //fileload解析request请求，返回list<FileItem>集合 List<FileItem> fileItems = fileUpload.parseRequest(request); for (FileItem fileItem : fileItems) { if (fileItem.isFormField()) { //是文本域 (处理文本域的函数) processFormField(fileItem); }else { //文件域 (处理文件域的函数) processUpLoadField1(fileItem); } } } catch (FileUploadException e) { e.printStackTrace(); } } /** * @param fileItem * */ private void processUpLoadField1(FileItem fileItem) { try { //获得文件读取流 InputStream inputStream = fileItem.getInputStream(); //获得文件名 String fileName = fileItem.getName(); //对文件名处理 if (fileName!=null) { fileName.substring(fileName.lastIndexOf(File.separator)+1); }else { throw new RuntimeException("文件名不存在"); } //对文件名重复处理// fileName=new String(fileName.getBytes("ISO-8859-1"),"UTF-8"); fileName=UUID.randomUUID()+"_"+fileName; //日期分类 SimpleDateFormat simpleDateFormat=new SimpleDateFormat("yyyy-MM-dd"); String date = simpleDateFormat.format(new Date()); //创建目录 File parent=new File(this.getServletContext().getRealPath("/WEB-INF/upload/"+date)); if (!parent.exists()) { parent.mkdirs(); } //上传文件 fileItem.write(new File(parent, fileName)); //删除临时文件（如果上传文件过大，会产生.tmp的临时文件） fileItem.delete(); } catch (IOException e) { System.out.println("上传失败"); e.printStackTrace(); } catch (Exception e) { } } /** * @param fileItem */ //文件域 private void processUpLoadField(FileItem fileItem) { try { //获得文件输入流 InputStream inputStream = fileItem.getInputStream(); //获得是文件名字 String filename = fileItem.getName(); //对文件名字处理 if (filename!=null) {// filename.substring(filename.lastIndexOf(File.separator)+1); filename = FilenameUtils.getName(filename); } //获得路径，创建目录来存放文件 String realPath = this.getServletContext().getRealPath("/WEB-INF/load"); File storeDirectory=new File(realPath);//既代表文件又代表目录 //创建指定目录 if (!storeDirectory.exists()) { storeDirectory.mkdirs(); } //防止文件名一样 filename=UUID.randomUUID()+"_"+filename; //目录打散 防止同一目录文件下文件太多，不好查找 //按照日期分类存放上传的文件 //storeDirectory = makeChildDirectory(storeDirectory); //多级目录存放上传的文件 storeDirectory = makeChildDirectory(storeDirectory,filename); FileOutputStream fileOutputStream=new FileOutputStream(new File(storeDirectory, filename)); //读取文件，输出到指定的目录中 int len=1; byte[] b=new byte[1024]; while((len=inputStream.read(b))!=-1){ fileOutputStream.write(b, 0, len); } //关闭流 fileOutputStream.close(); inputStream.close(); } catch (IOException e) { e.printStackTrace(); } } //按照日期来分类 private File makeChildDirectory(File storeDirectory) { SimpleDateFormat simpleDateFormat=new SimpleDateFormat("yyyy-MM-dd"); String date = simpleDateFormat.format(new Date()); //创建目录 File childDirectory=new File(storeDirectory, date); if (!childDirectory.exists()) { childDirectory.mkdirs(); } return childDirectory; } //多级目录 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) { //对于文本域的中文乱码，可以用new String()方式解决 try { String fieldName = fileItem.getFieldName();//表单中字段名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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