将图像上传到 restful 网络服务会产生无法查看的图像

Question

我正在使用以下解决方案尝试在用 java 编写的 restful 网络服务中接收图像：

@POST
@Consumes(MediaType.MULTIPART_FORM_DATA)
@Produces(MediaType.TEXT_PLAIN)
public String getFile(@FormDataParam("pic") InputStream file,
        @QueryParam("uid") String uid) {

    try {
        storeFile(file, uid);
    } catch (IOException ex) {
        Logger.getLogger(UploadImage.class.getName()).log(Level.SEVERE, null, ex);
        return "failed";
    }
    return "success";
}

private void storeFile(InputStream input, String uid) throws IOException {
    String absPath = PATH_TO_FILES + uid + ".jpg";
    try {
        OutputStream out = new FileOutputStream(new File(absPath));
        int read = 0;
        byte[] bytes = new byte[1024];

        out = new FileOutputStream(new File(absPath));
        while ((read = input.read(bytes)) != -1) {
            out.write(bytes, 0, read);
        }
        out.flush();
        out.close();
    } catch (IOException e) {

        e.printStackTrace();
    }
}

这是客户端代码（java脚本）：

$scope.fileSelect = function (files) {

var file = files[0];
  console.log("File loaded");
  console.log(files);
  console.log('uid = ' + $scope.uid + ' user = ' + $scope.user);
  var formData = new FormData();
  formData.append('pic', file);
  var requestBody = {"token": $scope.token};

    var req = {
        method: 'POST',
        url: 'http://192.168.0.9/resources/UploadPicture?uid=' + $scope.uid,
        headers: {
            'Content-Type': undefined
        },
        data: formData
    };
    console.log(FormData);
    $http(req).then(function(response){
        console.log(response);
    }, function(error){
        console.log(error);
    });


};

此代码生成一个不可查看的文件。我期待的文件是图像。所以我有 2 个问题：

每当调用网络服务时，响应都是 return，图像似乎没有完全刷新到硬盘。过了一会儿我可以编辑它。有没有办法在镜像实际刷新到磁盘时响应客户端？
如何让输入流在写入磁盘时生成可视图像？

--编辑--

在修改文件后，我意识到如果我在 notepad++ 中编辑图像并取消表单边界的开始和结束标记，图像将再次可见：

Produced File

有没有办法让表单边界不再干扰图像数据？

Answer 1

我找到了一个使用 apache commons fileupload 的解决方案：

@POST
@Consumes(MediaType.MULTIPART_FORM_DATA)
@Produces(MediaType.TEXT_PLAIN)
public String getFile(@Context HttpServletRequest request, @QueryParam("uid") String uid) {


    ServletFileUpload upload = new ServletFileUpload();
    try {
        FileItemIterator iter = upload.getItemIterator(request);
        while (iter.hasNext()) {
            FileItemStream item = iter.next();
            String name = item.getFieldName();
            InputStream stream = item.openStream();
            if (item.isFormField()) {
                System.out.println("Form field " + name + " with value "
                        + Streams.asString(stream) + " detected.");
            } else {
                System.out.println("File field " + name + " with file name "
                        + item.getName() + " detected.");
                // Process the input stream
              storeFile(stream, uid);
            }
        }

        return "success";

    } catch (FileUploadException ex) {
        Logger.getLogger(UploadImage.class.getName()).log(Level.SEVERE, null, ex);
    } catch (IOException ex) {
        Logger.getLogger(UploadImage.class.getName()).log(Level.SEVERE, null, ex);
    }
    return "failed.";
}

将图像上传到 restful 网络服务会产生无法查看的图像

Uploading an Image to a restful webservice produces an unviewable image

java

upload

multipartform-data

inputstream

jersey