package kr.bit.controller;

import java.io.File;
import java.io.IOException;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
public class FileAddController implements Controller{
	@Override
	public String requestHandler(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		String UPLOAD_DIR="file_repo";                                   // \\, /
		String uploadPath=request.getServletContext().getRealPath("")+File.separator+UPLOAD_DIR;
		File currentDirPath=new File(uploadPath); // 업로드할 경로를 File객체로 만들기
		if(!currentDirPath.exists()) {
			currentDirPath.mkdir();
		}
		// 파일을 업로드 할때 먼저 저장될 임시 저장경로를 설정
		// file upload시 필요한 API - commons-fileupload, commons-io
		DiskFileItemFactory factory=new DiskFileItemFactory();
		factory.setRepository(currentDirPath);
		factory.setSizeThreshold(1024*1024);

		String fileName=null;

		ServletFileUpload upload=new ServletFileUpload(factory);
		try {     // items-->FileItem[ ],FileItem[  ],FileItem[ ]
			List<FileItem> items=upload.parseRequest(request); // request안에 여러개의 파일이 업로드 된경우...
			for(int i=0;i<items.size();i++) {
				  FileItem fileItem=items.get(i);
				  if(fileItem.isFormField()) { //폼필드이면
					  System.out.println(fileItem.getFieldName()+"="+fileItem.getString("utf-8"));
				  }else { // 파일이면
					  if(fileItem.getSize()>0) {
						  int idx=fileItem.getName().lastIndexOf("\\"); // \\(Window), /(Linux)
						  //윈도우와 리눅스일 경우 마지막 인덱스 부분을 idx에 넣는다.
						  if(idx==-1) {
							  idx=fileItem.getName().lastIndexOf("/");
						  }
						  fileName=fileItem.getName().substring(idx+1); // 파일이름
						  File uploadFile=new File(currentDirPath+"\\"+fileName);
						  // 파일이 중복체크
						  if(uploadFile.exists()) {
							  fileName=System.currentTimeMillis()+"_"+fileName;
							  uploadFile=new File(currentDirPath+"\\"+fileName);
						  }
						  fileItem.write(uploadFile); //임시경로->새로운경로에 파일 쓰기
					  }
				  }
			}//_for_
		} catch (Exception e) {
			e.printStackTrace();
		}
		// $.ajax()쪽으로 업로드된 최종 파일이름을 전송시켜준다.
		response.setContentType("text/html;charset=euc-kr");
		response.getWriter().print(fileName);		
		return null;
	}
}

<div class="panel-body">
     <form id="form1" name="form1" class="form-horizontal" method="post">
	  <div class="form-group">
	    <label class="control-label col-sm-2" for="id">아이디:</label>
	    <div class="col-sm-10">
	      <table>
	        <tr>
	          <td><input type="text" class="form-control" id="id" name="id" placeholder="아이디를 입력하세요"></td>
	          <td><input type="button" value="중복체크" onclick="doublecheck()" class="btn btn-warning"></td>
	        </tr>	        
	      </table>
	    </div>
	  </div>
	  <div class="form-group">
	    <label class="control-label col-sm-2" for="pass">비밀번호:</label>
	    <div class="col-sm-10">
	      <input type="password" class="form-control" id="pass" name="pass" placeholder="비밀번호를 입력하세요" style="width: 30%">
	    </div>
	  </div>
	   <div class="form-group">
	    <label class="control-label col-sm-2" for="name">이름:</label>
	    <div class="col-sm-10">
	      <input type="text" class="form-control" id="name" name="name" placeholder="이름을 입력하세요" style="width: 30%">
	    </div>
	  </div>
	    <div class="form-group">
	    <label class="control-label col-sm-2" for="age">나이:</label>
	    <div class="col-sm-10">
	      <input type="text" class="form-control" id="age" name="age" placeholder="나이입력" style="width: 10%">
	    </div>
	  </div>
	    <div class="form-group">
	    <label class="control-label col-sm-2" for="email">이메일:</label>
	    <div class="col-sm-10">
	      <input type="text" class="form-control" id="email" name="email" placeholder="이메일을 입력하세요" style="width: 30%">
	    </div>
	  </div>
	    <div class="form-group">
	    <label class="control-label col-sm-2" for="pass">전화번호:</label>
	    <div class="col-sm-10">
	      <input type="text" class="form-control" id="phone" name="phone" placeholder="전화번호를 입력하세요" style="width: 30%">
	    </div>
	  </div>
	  <div class="form-group">
	    <label class="control-label col-sm-2" for="">첨부파일:</label>
	    <div class="col-sm-10">
	      <input type="file" class="control-label" id="file" name="file">
	    </div>
	  </div>