利用javaweb如何实现一个文件上传功能

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



 
 
 
 
 
 
  
 
 
 
 
 
 
  

  文件的描述：

  

   

   

   
   
  
 
   
  
 

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集合
   List 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();
   }
   
 }

}