java,单文件和多文件上传代码范例

上传一个单文件，用request.getFile得到文件（下面的功能是上传到阿里云）

   @RequestMapping(value = {"/content"}, method = RequestMethod.POST, headers = "content-type=multipart/form-data")
    public  String content(ModelMap modelMap,
                           MultipartHttpServletRequest request,
                           HttpServletResponse response){
        response.setHeader("Access-Control-Allow-Origin", "*");
        OSSUpload ossUpload = new OSSUpload("xinmeiti");
        Iterator<String> itr =  request.getFileNames();
        MultipartFile file = request.getFile(itr.next());
        Map<String, Object> map = new HashMap<>();
        try{
            byte[] bytes = org.apache.poi.util.IOUtils.toByteArray(file.getInputStream());
            String fileType = getImageType(bytes);
            String md5 = StringUtils.md5(String.valueOf(bytes));
            String fileName = firstName +"/"+md5 + "."+ fileType;
            Map<String, Object> uploadResult = ossUpload.upload(bytes, fileName);
            if(!uploadResult.get("status").equals(0)){
                modelMap.addAttribute("json", StringUtils.toJson(uploadResult));
            }else{
                map.put("url", cndName+fileName);
                modelMap.addAttribute("json", StringUtils.toJson(map));
            }
        } catch (IOException e) {
            modelMap.addAttribute("json", StringUtils.toJson(new ReturnMap(10004, "上传图片失败")));
            e.printStackTrace();
        }
        return "mis/json";
    }

上传多个文件，用request.getFile得到多文件

 @RequestMapping(value = {"multipleFileUpload"}, method =  {RequestMethod.GET, RequestMethod.POST})
    public  String multipleFileUpload(
            ModelMap modelMap,
            MultipartHttpServletRequest request,
            HttpServletResponse response,
            @RequestParam(value = "type") String type,
            @RequestParam(value = "jobId") String jobId) throws IOException {
        List < MultipartFile > files = request.getFiles("files");
        response.setHeader("Access-Control-Allow-Origin", "http://www.gifmiao.com");
        Map<String, Object> statusMap = new HashMap<>();
        HttpSession session = request.getSession();
        session.setAttribute("gifCompressStatus", statusMap);
        int compressSize = getCompressSizeByValue(type);
        for(MultipartFile file :files){
            String filename = file.getOriginalFilename().split(".gif")[0];
            Map<String, Object> resultMap = new HashMap<>();
            resultMap.put("size" , 0);
            resultMap.put("status" , 0);
            resultMap.put("url" , "");
            statusMap.put(filename, resultMap);
            InputStream is = file.getInputStream();
            byte[] bytes = IOUtils.toByteArray(is);
            CompressWorker worker = new CompressWorker(statusMap, bytes, filename, compressSize, jobId);
            worker.start();
        }
        modelMap.addAttribute("json", StringUtils.toInsensitiveJson(new ReturnMap("线程已启动")));
        return "json";
    }

在使用MultipartHttpServletRequest类型的时候需要注意，随便什么request都是MultipartHttpServletRequest
在这里举两个可以用MultipartHttpServletRequest的例子。
后端代码：上传一个单文件

 @RequestMapping(value = "/uploadInsight", method = RequestMethod.POST)
    public String uploadInsight(ModelMap modelMap,
                                MultipartHttpServletRequest request,
                                @RequestParam(value = "category") String category,
                                @RequestParam(value = "title") String title,
    ) throws IOException{
        Iterator<String> itr = request.getFileNames();
        MultipartFile file = request.getFile(itr.next());
        Map<String, Object> map = uploadImage(file);
        if(!map.get("state").equals("SUCCESS")){
            modelMap.addAttribute("json", StringUtils.toJson(new ReturnMap(10004, "上传图片失败")));
            return "mis/json";
        }
        String fengmianImgUrl = (String) map.get("name");
        InsightModel insightModel = new InsightModel();
        insightModel.setCategory(category);
        insightModel.setThumbnail(fengmianImgUrl);
        insightModel.setTitle(title);
        datastore.save(insightModel);
        modelMap.addAttribute("json", StringUtils.toJson((new ReturnMap("OK"))));
        return "mis/json";
    }

对应的前端代码可以是这样：（原生的js）

function upload(user){            //user是从表单里面接到的数据
 var formData = new FormData();
            formData.append("title", user.title);
            formData.append("file", user.file);
            formData.append("category", user.category);
            var xhr = new XMLHttpRequest();
            xhr.open('POST', "/editor/uploadInsight");
            //xhr.withCredentials = true;     //这个是关于跨域证书的
            xhr.onload = function(){
                if(xhr.readyState == 4 && xhr.status == 200){
 　　　　　　　　　　　　console.log("成功")
                }
            };
            xhr.send(formData);
}

对应的前端代码也可以是这样：（jquery方式调用）

   var formData = new FormData();
    formData.append("file", file);
    formData.append("title", title);
    formData.append("category", category);

    $.ajax({
        type : "POST",
        url  : "/editor/uploadInsight",
        data : formData,
        processData : false,
        contentType : false ,
        file:file,
        error: function(data) {
            
        },
        success: function(data) {
            
        },
        xhr: function() {
        
        }
    });