从安卓/Java上传Base64到RoR Carrierwave

Question

我尝试从使用 Carrierwave 的 base64 图像添加解决方案，以上传来自 Java 类的图像。这是现在我的 FileUploader 类的样子 - 我认为问题就在这里：

# encoding: utf-8

class FileUploader < CarrierWave::Uploader::Base

  # Include RMagick or MiniMagick support:
    include CarrierWave::RMagick
  # include CarrierWave::MiniMagick

  # Choose what kind of storage to use for this uploader:
  storage :file
  # storage :fog

  #START FROM BASE64 POST LINKED ABOVE
  class FilelessIO < StringIO
    attr_accessor :original_filename
    attr_accessor :content_type
  end

  before :cache, :convert_base64

  def convert_base64(file)
    if file.respond_to?(:original_filename) &&
        file.original_filename.match(/^base64:/)
      fname = file.original_filename.gsub(/^base64:/, '')
      ctype = file.content_type
      decoded = Base64.decode64(file.read)
      file.file.tempfile.close!
      decoded = FilelessIO.new(decoded)
      decoded.original_filename = fname
      decoded.content_type = ctype
      file.__send__ :file=, decoded
    end
    file
  end
#END FROM POST LINKED ABOVE


  # Override the directory where uploaded files will be stored.
  # This is a sensible default for uploaders that are meant to be mounted:
  def store_dir
    "uploads/#{model.class.to_s.underscore}/#{model.user_id}"
  end

  # Provide a default URL as a default if there hasn't been a file uploaded:
  # def default_url
  #   "/images/fallback/" + [version_name, "default.png"].compact.join('_')
  # end

  # Process files as they are uploaded:
  # process :scale => [200, 300]
  #
  # def scale(width, height)
  #   # do something
  # end

  # Create different versions of your uploaded files:
    version :thumb do
      process :resize_to_fit  => [200, 300]
    end

    version :web do
      process :resize_to_fit  => [1000, 1000]
    end

  # Add a white list of extensions which are allowed to be uploaded.
  # For images you might use something like this:
   def extension_white_list
     %w(jpg jpeg gif png)
   end

  # Override the filename of the uploaded files:
  # Avoid using model.id or version_name here, see uploader/store.rb for details.
   def filename
     if original_filename
     Time.new.to_i.to_s+"_"+original_filename
     end
   end

end

图片模型：

class Picture < ActiveRecord::Base

  belongs_to :user
  belongs_to :folders

  attr_accessible :user_id, :picture_name, :picture_description,
    :folder_id, :picture_path, :file_save

  mount_uploader :picture_path, FileUploader

   before_save :update_pictures_attributes

  def update_pictures_attributes
      self.file_size = picture_path.file.size
  end

end

目前当post请求被发出时，保存在数据库中的文件路径为nil，但所有其他信息都已保存。这是Java/Android类：

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.http.client.*;
import org.apache.http.client.entity.*;
import org.apache.http.client.methods.*;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.*;
import org.apache.http.message.*;
import org.apache.commons.io.FileUtils;
import org.json.*;
import android.util.Base64;
import android.util.Log;

public class Uploader {

    private String url;
    private String fileName;

    public Uploader(String url, String fileName){
        this.url = url;
        this.fileName = fileName;
    }

    public Boolean upload() throws JSONException, ClientProtocolException, IOException {
        Boolean success = true;
        JSONObject jsonObject = constructPictureJson();
            DefaultHttpClient httpClient = new DefaultHttpClient();

            ResponseHandler <String> responseHandler = new BasicResponseHandler();
            HttpPost postMethod = new HttpPost(url);
            postMethod.setEntity(new StringEntity(jsonObject.toString()));
            postMethod.setHeader("Accept", "application/json");
            postMethod.setHeader("Content-type", "application/json");
            postMethod.setHeader("Data-type", "json");
            try{
            httpClient.execute(postMethod, responseHandler);
            } catch (org.apache.http.client.HttpResponseException error){
                Log.d("Uploader Class Error", "Error code: "+error.getStatusCode());
                Log.d("Uploader Class Error", "Error message: "+error.getMessage());
                success = false;
            }
            //Log.d("server resposne", response);
            return success;
    }

    public JSONObject constructPictureJson() throws JSONException, IOException{
        String userId = "1"; 
        String folderId = "1";
        String[] file = fileName.split("/");
        JSONObject pictureData = new JSONObject();
        pictureData.put("user_id", userId);
        pictureData.put("folder_id", folderId); 
        pictureData.put("picture_name", "picture name");
        pictureData.put("picture_description", "1"); 
        pictureData.put("content_type", "jpg");
        pictureData.put("original_filename", "base64:"+file[file.length-1]);
        pictureData.put("filename", file[file.length-1]);
        pictureData.put("picture_path", encodePicture(fileName));

        return pictureData;
    }

    public String encodePicture(String fileName) throws IOException{
        File picture = new File(fileName);
        return Base64.encodeToString(FileUtils.readFileToByteArray(picture), Base64.DEFAULT);
    }

}

有没有人有什么想法？我已经卡在这个问题上一整天了。我认为可能是因为我不太懂Ruby，所以要么（1）请求格式不正确；要么（2）我没有正确地使用Carrierwave实现base64图像。

- TomJ

Answer 1

问题终于解决了！我希望这个答案能帮助到其他试图解决此问题但找不到好资源的人。令人惊讶的是，我觉得其他人也会想要做同样的事情。我的原始更改似乎是死路一条。

最终解决方案是在控制器中创建上传的图像对象，然后将其注入回参数中。

对于这个特定的示例，我们正在使用base64文件（我假设您已经有了它，因为JSON不支持嵌入式文件）并将其保存为系统中的临时文件，然后我们创建了那个UploadedFile对象，并最终将其重新注入到参数中。

我的json/params长这样：

picture {:user_id => "1", :folder_id => 1, etc., :picture_path {:file => "base64 awesomeness", :original_filename => "my file name", :filename => "my file name"}}

这是我的控制器现在的样子:

40        # POST /pictures
41    # POST /pictures.json
42    def create
43  
44      #check if file is within picture_path
45      if params[:picture][:picture_path]["file"]
46           picture_path_params = params[:picture][:picture_path]
47           #create a new tempfile named fileupload
48           tempfile = Tempfile.new("fileupload")
49           tempfile.binmode
50           #get the file and decode it with base64 then write it to the tempfile
51           tempfile.write(Base64.decode64(picture_path_params["file"]))
52     
53           #create a new uploaded file
54           uploaded_file = ActionDispatch::Http::UploadedFile.new(:tempfile => tempfile, :filename => picture_path_params["filename"], :original_filename => picture_path_params["original_filename"]) 
55     
56           #replace picture_path with the new uploaded file
57           params[:picture][:picture_path] =  uploaded_file
58     
59      end
60  
61      @picture = Picture.new(params[:picture])
62  
63      respond_to do |format|
64        if @picture.save
65          format.html { redirect_to @picture, notice: 'Picture was successfully created.' }
66          format.json { render json: @picture, status: :created, location: @picture }
67        else
68          format.html { render action: "new" }
69          format.json { render json: @picture.errors, status: :unprocessable_entity }
70        end
71      end
72    end

在这一点上唯一要做的事情就是删除临时文件，我相信可以通过tempfile.delete完成。

希望这对你的问题有所帮助！昨天我花了一整天的时间寻找解决方案，但是我发现所有的方法都行不通。然而，这个方法在我的测试用例中是有效的。

- TomJ

---

这很顺利！感谢您。不过，我最终将参数处理放入了before_filter：process_attached_file，only：：create调用中，以帮助保持创建方法更加清洁。 - Josh Kovach

我也在尝试做同样的事情，你能否发布你的安卓应用的最终Java代码？ - scientiffic

你介意分享一下你在安卓端上传功能的最终实现吗？我也做了类似的事情，而且我也在使用 Rails，但实际的上传非常慢 - 我猜这是因为我在 webrick 上测试，但我很想知道在上传之前，你是否将图像缩小或减少分辨率。 - Riptyde4