JavaWeb文件上传入门教程

 boolean isMultipart = ServletFileUpload.isMultipartContent(request);
  if(!isMultipart)
  {
  System.out.println("上传方式错误！");
  return;
  }

ServletFileUpload upload = new ServletFileUpload(factory);5.解析 


 //解析
         List items = upload.parseRequest(request);
  for(FileItem item: items)
  {
  if(item.isFormField()){//普通字段,表单提交过来的
    String fieldName = item.getFieldName();//表单信息的字段名
    String fieldValue = item.getString(); //表单信息字段值
    System.out.println(fieldName+"="+fieldValue);
  }else//文件处理
  {
   InputStream in = item.getInputStream();
   //上传文件名           C:\Users\Administrator\Desktop\a.txt
   String name = item.getName();  //只需要 a.txt
   String fileName = name.substring(name.lastIndexOf("\\")+1);
   //构建输出流
   String storeFile = storePath+"\\"+fileName;//上传文件的保存地址
   OutputStream out = new FileOutputStream(storeFile);
   byte[] b = new byte[1024];
   int len = -1;
   while((len=in.read(b))!=-1)
   {
   out.write(b, 0, len);
   }
   in.close();//关闭流
   out.close();
  }
  }

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



 
  
  
  
  
 
 
   
 
 
 

 
 
 
 
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package com.liuzhen.upload;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.List;

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;
//文件上传入门案例
public class UploadServlet2 extends HttpServlet {

 public void doGet(HttpServletRequest request, HttpServletResponse response)
  throws ServletException, IOException {
 
 //设置编码
 request.setCharacterEncoding("UTF-8");
 response.setContentType("text/html;charset=UTF-8");
 try {
  //上传文件的路徑
  String storePath = getServletContext().getRealPath("/WEB-INF/files");
  //设置环境
  DiskFileItemFactory factory = new DiskFileItemFactory();
  //判断表单传送方式 form enctype=multipart/form-data
  boolean isMultipart = ServletFileUpload.isMultipartContent(request);
  if(!isMultipart)
  {
  System.out.println("上传方式错误！");
  return;
  }
  ServletFileUpload upload = new ServletFileUpload(factory);
  //解析
  List items = upload.parseRequest(request);
  for(FileItem item: items)
  {
  if(item.isFormField()){//普通字段,表单提交过来的
    String fieldName = item.getFieldName();//表单信息的字段名
    String fieldValue = item.getString(); //表单信息字段值
    System.out.println(fieldName+"="+fieldValue);
  }else//文件处理
  {
   InputStream in = item.getInputStream();
   //上传文件名           C:\Users\Administrator\Desktop\a.txt
   String name = item.getName();  //只需要 a.txt
   String fileName = name.substring(name.lastIndexOf("\\")+1);
   //构建输出流
   String storeFile = storePath+"\\"+fileName;//上传文件的保存地址
   OutputStream out = new FileOutputStream(storeFile);
   byte[] b = new byte[1024];
   int len = -1;
   while((len=in.read(b))!=-1)
   {
   out.write(b, 0, len);
   }
   in.close();//关闭流
   out.close();
  }
  }
 } catch (FileUploadException e) {
  throw new RuntimeException(e);
 }

 }

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

}