javaweb实现文件上传示例代码

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();
   }

 }

}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持我们。