将图像从android上传到golang服务器并将其保存在mongodb中

Question

I'm trying to upload an image from android device to my golang server and save it in db. If I understood correctly, first I need to deserialize bytes from request into Image{} struct, then persist it into db (I use mongodb) But i've got a panic with "image: unknown format"

Here are my code snippets:

client:

private File createImageFile() throws IOException {
    String imageFileName = "avatar";
    File storageDir = mViewManager.getContext().getExternalFilesDir(Environment.DIRECTORY_PICTURES);
    File image = File.createTempFile(
            imageFileName,  /* prefix */
            ".jpeg",         /* suffix */
            storageDir      /* directory */
    );

    mCurrentPhotoPath = "file:" + image.getAbsolutePath();
    return image;
}

...

public void uploadAvatar(File avatar) {
    RequestBody avBody = RequestBody.create(MediaType.parse("image/*"), avatar);
    Call<Boolean> call = service.uploadAvatar(avBody);
    call.enqueue(new Callback<Boolean>() {
        @Override
        public void onResponse(Call<Boolean> call, Response<Boolean> response) {
        }

        @Override
        public void onFailure(Call<Boolean> call, Throwable t) {
        }
    });
}

...

@Multipart
@POST("profile/avatar/save")
Call<Boolean> uploadAvatar(@Part("file\"; filename=\"avatar.jpeg\" ") RequestBody avatar);

server:

func HandleAvatarSave(w http.ResponseWriter, r *http.Request) {
    data, err := ioutil.ReadAll(r.Body)
    if err != nil {
        panic(err)
    } else {
        //fmt.Println("data", data)
        buf := bytes.NewBuffer(data)
        if img, _, err := image.Decode(buf); err != nil {
            panic(err)
        } else {
            // persist data, not implemented yet
        }
    }
}

Thanks in advance!

Answer 1

I dont do Android, so cant assure you much. But I use the below golang implementation to upload a file.

package main

import (
    "io"
    "net/http"
    "os"
)

//Display the named template
func display(w http.ResponseWriter, tmpl string, data interface{}) {
    templates.ExecuteTemplate(w, tmpl+".html", data)
}

//This is where the action happens.
func uploadHandler(w http.ResponseWriter, r *http.Request) {
    switch r.Method {
    //POST takes the uploaded file(s) and saves it to disk.
    case "POST":
        //parse the multipart form in the request
        err := r.ParseMultipartForm(100000)
        if err != nil {
            http.Error(w, err.Error(), http.StatusInternalServerError)
            return
        }

        //get a ref to the parsed multipart form
        m := r.MultipartForm

        //get the *fileheaders
        files := m.File["myfiles"]
        for i, _ := range files {
            //for each fileheader, get a handle to the actual file
            file, err := files[i].Open()
            defer file.Close()
            if err != nil {
                http.Error(w, err.Error(), http.StatusInternalServerError)
                return
            }
            //create destination file making sure the path is writeable.
            dst, err := os.Create("/home/sanat/" + files[i].Filename)
            defer dst.Close()
            if err != nil {
                http.Error(w, err.Error(), http.StatusInternalServerError)
                return
            }
            //copy the uploaded file to the destination file
            if _, err := io.Copy(dst, file); err != nil {
                http.Error(w, err.Error(), http.StatusInternalServerError)
                return
            }

        }
        //display success message.
        display(w, "upload", "Upload successful.")
    default:
        w.WriteHeader(http.StatusMethodNotAllowed)
    }
}

func main() {
    http.HandleFunc("/upload", uploadHandler)

    //static file handler.
    http.Handle("/assets/", http.StripPrefix("/assets/", http.FileServer(http.Dir("assets"))))

    //Listen on port 8080
    http.ListenAndServe(":8080", nil)
}

I quick google took me to this android snippet. You will need httpClient 4 or higher

package com.isummation.fileupload;

import java.io.BufferedReader;
import java.io.ByteArrayOutputStream;
import java.io.InputStreamReader;

import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.mime.HttpMultipartMode;
import org.apache.http.entity.mime.MultipartEntity;
import org.apache.http.entity.mime.content.ByteArrayBody;
import org.apache.http.entity.mime.content.StringBody;
import org.apache.http.impl.client.DefaultHttpClient;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.Bitmap.CompressFormat;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.util.Log;

public class FileUpload extends Activity {
    Bitmap bm;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        try {
            // bm = BitmapFactory.decodeResource(getResources(),
            // R.drawable.forest);
            bm = BitmapFactory.decodeFile("/sdcard/DCIM/forest.png");
            executeMultipartPost();
        } catch (Exception e) {
            Log.e(e.getClass().getName(), e.getMessage());
        }
    }

    public void executeMultipartPost() throws Exception {
        try {
            ByteArrayOutputStream bos = new ByteArrayOutputStream();
            bm.compress(CompressFormat.JPEG, 75, bos);
            byte[] data = bos.toByteArray();
            HttpClient httpClient = new DefaultHttpClient();
            HttpPost postRequest = new HttpPost(
                    "http://10.0.2.2/cfc/iphoneWebservice.cfc?returnformat=json&method=testUpload");
            ByteArrayBody bab = new ByteArrayBody(data, "forest.jpg");
            // File file= new File("/mnt/sdcard/forest.png");
            // FileBody bin = new FileBody(file);
            MultipartEntity reqEntity = new MultipartEntity(
                    HttpMultipartMode.BROWSER_COMPATIBLE);
            reqEntity.addPart("uploaded", bab);
            reqEntity.addPart("photoCaption", new StringBody("sfsdfsdf"));
            postRequest.setEntity(reqEntity);
            HttpResponse response = httpClient.execute(postRequest);
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    response.getEntity().getContent(), "UTF-8"));
            String sResponse;
            StringBuilder s = new StringBuilder();

            while ((sResponse = reader.readLine()) != null) {
                s = s.append(sResponse);
            }
            System.out.println("Response: " + s);
        } catch (Exception e) {
            // handle exception here
            Log.e(e.getClass().getName(), e.getMessage());
        }
    }
}