Android:使用json上传图片

Question

我正在尝试将位图从我的 Android 应用程序上传到我的 NodeJS 服务器。我的位图有一些数据(Json)，必须在同一(POST)消息中上传。我发现可以通过以下方式实现:

• 多部分表单数据。
• 在应用端进行图像编码(将图像转换为字符串)，在服务器端进行解码。

还有更好的办法吗？有谁熟悉执行此类上传的良好指南吗？

Answer 1

感谢您的回复。这是我为分段上传编写的代码(多个答案的合并)。如果代码有任何问题，请告诉我。

    // create a url object
    URL url = new URL(mGlobalUrl + localUrl);
    HttpURLConnection conn = (HttpURLConnection) url.openConnection();

    conn.setDoInput(true);
    conn.setDoOutput(true);
    conn.setUseCaches(false);

    conn.setRequestMethod("POST");
    conn.setRequestProperty("Connection", "Keep-Alive");
    conn.setRequestProperty("User-Agent", "Android Multipart HTTP Client 1.0");
    conn.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + boundary);

    DataOutputStream outputStream = new DataOutputStream(conn.getOutputStream());

    //--start--
    //Deal with data
    outputStream.writeBytes(twoHyphens + boundary + lineEnd);           //key
    outputStream.writeBytes("Content-Disposition: form-data; name=\"key\"" + lineEnd);
    outputStream.writeBytes(lineEnd);
    outputStream.writeBytes(value);    //value
    outputStream.writeBytes(lineEnd);

    //Deal with image
    outputStream.writeBytes(twoHyphens + boundary + lineEnd);           //key
    outputStream.writeBytes("Content-Disposition: form-data; name=\"uploadFile\"; filename=\"" + "image1" + "\"" + lineEnd);
    //outputStream.writeBytes("Content-Type: " + fileMimeType + lineEnd);
    outputStream.writeBytes("Content-Transfer-Encoding: binary" + lineEnd);
    outputStream.writeBytes(lineEnd);

    FileInputStream fileInputStream = new FileInputStream(imagePath);   //value
    int bytesAvailable = fileInputStream.available();
    int bufferSize = Math.min(bytesAvailable, maxBufferSize);
    byte[] buffer = new byte[bufferSize];

    int bytesRead = fileInputStream.read(buffer, 0, bufferSize);
    while (bytesRead > 0) {
        outputStream.write(buffer, 0, bufferSize);
        bytesAvailable = fileInputStream.available();
        bufferSize = Math.min(bytesAvailable, maxBufferSize);
        bytesRead = fileInputStream.read(buffer, 0, bufferSize);
    }
    outputStream.writeBytes(lineEnd);

    outputStream.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);
    //--end--

    // receive response as inputStream
    int responseCode = conn.getResponseCode();
    if (responseCode == HttpsURLConnection.HTTP_OK) {
        inputStream = new BufferedInputStream(conn.getInputStream());

        // convert input stream to string
        if (inputStream != null) {
            result = convertInputStreamToString(inputStream);
        }
        else {

            Log.d(TAG, "sendPostRequest: Error - input stream is null");
            result = "{}";
        }
    }

    fileInputStream.close();
    outputStream.flush();
    outputStream.close();
    conn.disconnect();

对于服务器端(NodeJS)，我使用了 Formidable 模块(我不确定它是否已弃用)，您可以找到有关此模式的更多信息 here 。

upload_image = function(req, res, next) {

//create new incoming form object
var form = new formidable.IncomingForm();

//parse the request using formidable module
form.parse(req, function(error, fields, files) {

    //check if error occurred during the parse
    if (error) {
        ...some code
        return;
    }

    //save the data received in the request
    ...some code 
});

//check for errors during the transmission
form.on('error', function(err) {
    ...some code
    return;
});

//check for the end of the transmission
form.on('end', function(error, fields, files) {
    //save the temporary location of the uploaded image file
    var temp_path = this.openedFiles[0].path;

    //save the file name of the uploaded image file
    var file_name = this.openedFiles[0].name;

    //save the file
    ...some code

    //update the database
    ...some code
};