javaweb上传下载实例完整版解析(上)

<div>
 <h5>文件上传</h5><hr/> 
 <form id="file_upload_id" name="file_upload_name" > 
 <div><input type="file" name="file_upload"/></div>
 <div onclick = "upload()"><input type="button" value="上传" /></div><br>
 <div>
 <span id="typeValue"></span>
 <input id="type" type="hidden" name="input_type">
 </div>
 <div>
 <span id="sizeValue"></span>
 <input id="size" type="hidden" name="input_size">
 </div>
 </form> 
</div> 

<script>
$(function(){
 a();
}); 

 function a(){
 var size=1024 * 1024 * 50;
 var type=
 "gif,jpg,jpeg,png,bmp,swf,flv,mp3,wav,wma,wmv,mid,avi,mpg,asf,rm,rmvb,doc,docx,xls,xlsx,ppt,htm,html,txt,zip,rar,gz,bz2,jsp";
 $("#type").val(type);//利用input传值到后台
 $("#typeValue").html("文件格式限制为:"+type);//显示
 $("#size").val(size);
 $("#sizeValue").html("文件大小限制为:"+size);
 } 

 function upload(){
 var formdata = new FormData($('#file_upload_id')[0]); 
 $.ajax({
 url: 'cloud/load/upload', 
 type: 'POST', 
 data: formdata, 
 dataType:'JSON',
 cache: false, 
 processData: false, 
 contentType: false ,
 success : function(date){
 alert("success"); 
 }, 
 error : function(e){
 alert("error");
 }
 });
 }
</script>

package com.cloud.web.controller;

import java.io.IOException;
import java.util.HashMap;
import javax.annotation.Resource;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.multipart.MultipartFile;
import com.cloud.web.service.FileLoadService;

@Controller
@RequestMapping("/load")
public class LoadController {

 @Resource
 public FileLoadService fileLoadService;

 @RequestMapping(value = "/upload", method = RequestMethod.POST)
 @ResponseBody
 public HashMap<String,Object> upload(@RequestParam("file_upload") MultipartFile file,@RequestParam("input_type") String extName,@RequestParam("input_size") String size, HttpServletRequest request, HttpServletResponse response, ModelMap model) throws ServletException, IOException {
 HashMap<String,Object> map = new HashMap<String,Object>();
 request.setCharacterEncoding("UTF-8");// 解决上传的中文文件乱码问题 
 response.setContentType("text/html;charset=UTF-8"); 
 long fileSizeMax=Long.parseLong(size);
 String mes =fileLoadService.doUpload(file,request, extName, fileSizeMax);
 map.put("mes", mes);
 return map; 
 }

}

package com.cloud.web.service.impl;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

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

import org.springframework.stereotype.Service;
import org.springframework.web.multipart.MultipartFile;

import com.cloud.web.service.FileLoadService;

@Service
public class FileLoadServiceImpl implements FileLoadService{

 @Override 
 public String doUpload(MultipartFile file, HttpServletRequest request, String extName, long fileSizeMax) throws ServletException, IOException{

 // 存放路径 
 String realPath = request.getSession().getServletContext().getRealPath("/WEB-INF/")+"/upload/test/"; 
 String msg="";//返回消息
 try { 
  String fileName = file.getOriginalFilename();// 获取上传的文件的文件名
  String fileExt = fileName.substring(fileName.lastIndexOf(".") + 1).toLowerCase();// 获取上传文件的扩展名  

  if (fileName != null) { 
  System.out.println("上传的文件的扩展名是：" + fileExt);  
  if(!extName.contains(fileExt)){ 
   System.out.println("上传文件扩展名是不允许的扩展名：" + fileExt);
   msg = msg + "文件：" + fileName + "，上传文件扩展名是不允许的扩展";

   }else if(file.getSize() > fileSizeMax){  
   // 如果需要限制上传的文件大小，不超过最大限制
   System.out.println("上传文件大小：" + file.getSize());
   msg = msg + "文件：" + fileName + "，上传文件大小超过限制大小";   
   }else{
   Date now = new Date(); 
   DateFormat df = new SimpleDateFormat("yyyyMMddHHmmss"); 
   String str = df.format(now);     
   String nFileName=str+"_"+fileName;

   // 生成一个子目录 
   String childDirectory = genChildDirectory(realPath); 
   File storeDirectory = new File(realPath + File.separator + childDirectory); 
   //如果目录不存在，就创建一个 
   if (!storeDirectory.exists()) { 
   storeDirectory.mkdirs(); 
   } 
   // 获取item中的上传文件的输入流
   InputStream is = file.getInputStream();
   //创建一个文件输出流
   FileOutputStream out = new FileOutputStream(storeDirectory + "\\" + nFileName);
   //创建一个缓冲区
   byte buffer[] = new byte[1024];
   //判断输入流中的数据是否已经读完的标致
   int len = 0;
   while((len = is.read(buffer)) > 0){
   out.write(buffer, 0, len);
   }

   out.close();//关闭输出流
   is.close(); //关闭输入流   
   msg="file：" + fileName + "，success";
   }
  } 

 } catch (Exception e) { 
  e.printStackTrace(); 
 }  
 return msg;
 }

 // 按照时间创建分目录 放置一个文件夹下面的文件过多 
 @Override
 public String genChildDirectory(String realPath) { 
 Date now = new Date(); 
 DateFormat df = new SimpleDateFormat("yyyy-MM-dd"); 
 String str = df.format(now); 

 File file = new File(realPath, str); 
 if (!file.exists()) { 
  file.mkdirs(); 
 } 
 return str; 
 }
}