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();
    }