Play框架上的单个POST请求中的多个文件上载和json对象

Question

我有一个Windows Phone 8客户端发出以下帖子请求:

public async Task<string> DoPostRequestAsync(String URI, JSonWriter jsonObject, ObservableCollection<byte[]> attachments)
    {
        var client = new RestClient(DefaultUri);

        var request = new RestRequest(URI, Method.POST);
        request.AddParameter("application/json; charset=utf-8", jsonObject.ToString(), ParameterType.RequestBody);

        // add files to upload
        foreach (var a in attachments)
            request.AddFile("picture", a, "file.jpg");

        var content = await client.GetResponseAsync(request);

        return content;
    }

从RestSharp文档中我读到,通过向请求添加文件,它会自动作为"multipart/form-data"请求.

Play 2.1中的上传操作控制器如下:

@BodyParser.Of(BodyParser.Json.class)
public static Result createMessage() {
    JsonNode json = request().body().asJson();
    ObjectNode result = Json.newObject();
    String userId = json.findPath("userId").getTextValue();
    String rayz = json.findPath("message").getTextValue();

    Http.MultipartFormData body = request().body().asMultipartFormData();
    Http.MultipartFormData.FilePart picture = body.getFile("picture");

    if (picture != null) {
        String fileName = picture.getFilename();
        String contentType = picture.getContentType();
        File file = picture.getFile();

        result.put("status", "success");
        result.put("message", "Created message!");
        return badRequest(result);
    } else {
        result.put("status", "error");
        result.put("message", "Message cannot be created!");
        return badRequest(result);
    }
}

请注意,在application.conf上我设置了以下内容以增加大小限制(似乎不起作用):

# Application settings
# ~~~~~
parsers.text.maxLength=102400K

现在,每次我尝试发出POST请求时,我都会在调试器上注意到IsMaxSizeEsceeded变量始终为true,并且multipart变量为null.当我尝试使用以下控制器上传一个文件nu时,一切似乎都正常工作.大小不是问题,并且设置了multipart变量.

public static Result singleUpload() {
    ObjectNode result = Json.newObject();

    Http.MultipartFormData body = request().body().asMultipartFormData();
    Http.MultipartFormData.FilePart picture = body.getFile("picture");
    if (picture != null) {
        String fileName = picture.getFilename();
        String contentType = picture.getContentType();
        File file = picture.getFile();
        result.put("status", "success");
        result.put("message", "File uploaded!");
        return badRequest(result);
    } else {
        result.put("status", "error");
        result.put("message", "File cannot be uploaded!");
        return badRequest(result);
    }
}

问题是附件/文件应该与JSON对象一起发送/上传到单个POST请求中的服务器而不是单独发送.

有没有人遇到过类似的问题？是否可以实现这一点 - 使用Play 2.1在一个POST请求中发送一个json对象和多个要上传到服务器上的文件？

Answer 1

找到了做到这一点的方法.以防万一其他人试图在将来做类似的事情.

因此,首先必须通过以下方式完成RestSharp客户端的请求:

public async Task<string> DoPostRequestWithAttachmentsAsync(String ext, JSonWriter jsonObject, ObservableCollection<byte[]> attachments) {
    var client = new RestClient(DefaultUri);
    var request = new RestRequest(ext, Method.POST);

    request.RequestFormat = DataFormat.Json;
    request.AddParameter("json", jsonObject.ToString(), ParameterType.GetOrPost);

    // add files to upload
    foreach (var a in attachments)
        request.AddFile("attachment", a, "someFileName");

    var content = await client.GetResponseAsync(request);

    if (content.StatusCode != HttpStatusCode.OK)
            return <error>;

    return content.Content;
}

现在进入Play控制器如下:

public static Result createMessage() {
    List<Http.MultipartFormData.FilePart> attachments;
    String json_str;

    Http.MultipartFormData body = request().body().asMultipartFormData();

    // If the body is multipart get the json object asMultipartFormData()
    if (body!=null) {
        json_str = request().body().asMultipartFormData().asFormUrlEncoded().get("json")[0];
        attachments= body.getFiles();
    }
    // Else, if the body is not multipart get the json object asFormUrlEncoded()
    else {
        json_str = request().body().asFormUrlEncoded().get("json")[0];
        attachments = Collections.emptyList();
    }

    // Parse the Json Object
    JsonNode json = Json.parse(json_str);

    // Iterate through the uploaded files and save them to the server
    for (Http.MultipartFormData.FilePart o : attachments)
        FileManager.SaveAttachmentToServer(o.getContentType(), o.getFile());

    return ok();
}

因此,RestSharp端的错误似乎是json对象上的ParameterType.RequestBody; 并且在控制器中,大小并没有真正改变任何东西..但重要的部分是不使用@ BodyParser.Of(BodyParser.Json.class),因为这会将整个请求体转换为json对象.与发送到服务器的文件相结合会触发isMaxSizeExceeded标志.

最后,控制器中的多部分文件处理如上所示,唯一棘手的部分是附件是可选的,这意味着必须处理它.