java,单文件和多文件上传代码范例

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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() {

        }

    });