java Web 文件上传

注意：请求实体过大的问题，请修改Nginx服务器的大小（百度参考413 Request Entity Too Large 的解决方法）
jsp：<input type="file"  style="height: 114px;width: 100%;position: absolute;opacity: 0;" name="file1" id="file1" >

$(function(){

        $("#file1").change(function(){
            //创建FormData对象
            var data = new FormData();
            //为FormData对象添加数据
            $.each($('#file1')[0].files, function(i, file) {
                     data.append('upload_file', file);
             });
            $.ajax({
                 url:'${pageContext.request.contextPath}/uploadImage',
                 type:'POST',
                 data:data,
                 cache: false,
                 contentType: false,    //不可缺
                 processData: false,    //不可缺
                 success:function(data){
                    //显示追加
                     var imgUrl="/"+data;
                     var showImg = "<div class='img-item'>" +
                             "<img src='" + imgUrl + "'>" +
                             "<span class='close-item iconfont'></span>" +
                             "</div>";
                     $("#addImg").before(showImg);
                     //数据追加
                     var inputImg = "<input type='hidden' name='postImage'value='" + imgUrl + "' >";
                     $("#typeId").after(inputImg);
                  }
             });
         });
    });

java后台部分：

     @RequestMapping(value = "/uploadImage", method = RequestMethod.POST)
     @ResponseBody
     public String uploadImage(HttpServletRequest request) throws IOException {
         MultipartHttpServletRequest multipartRequest = (MultipartHttpServletRequest)request;
         Iterator<String> iterator = multipartRequest.getFileNames();
         String fileName = "";
         SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
         String dir = "upload/" + sdf.format(new Date()) + "/";
         String realPath = request.getSession().getServletContext().getRealPath("/");
         while(iterator.hasNext()){
             MultipartFile multipartFile = multipartRequest.getFile(iterator.next());
             if(multipartFile != null){
                 String fn = multipartFile.getOriginalFilename();
                 String suffix = fn.substring(fn.lastIndexOf("."));
                 fileName = dir  + Utils.getRandomStringByLength(6) + suffix;
                 String path = realPath + fileName;
                 path = path.replace("\\", "/");
                 File f = new File(path);
                 if(!f.mkdirs()){
                     f.mkdir();
                 }
                 multipartFile.transferTo(f);
             }
         }
         return fileName;
     }
 　　//    上面方法需要用到下面的方法
28　　 public String getRandomStringByLength(int length) {
         String base = "abcdefghijklmnopqrstuvwxyz0123456789";
         Random random = new Random();
         StringBuffer sb = new StringBuffer();
         for (int i = 0; i < length; i++) {
             int number = random.nextInt(base.length());
             sb.append(base.charAt(number));
         }
         return sb.toString();
     }