从Android上传图像到PHP的有效方法

Question

I am uploading an image to PHP from Android by converting it to the byte array. After that I simply submit it using POST method.

On server side I do the reverse of what I am doing at client (Android app) side.

I was wondering if there is any other good/efficient/smart way to do this.

Note: I only have to use only PHP/JS/HTML and obviously Java at client side.

Answer 1

One of the most efficient ways is doing it using Volley, so make sure to include it in your gradle:

compile 'com.android.volley:volley:1.0.0'

I personally use Universal Image Loader which is included automatically when you include Volley. Since you haven't put any code that you tried, i'll give you some examples. In your activity that you're trying to upload the image, create a button. Add this code when that button is clicked:

Intent i = new Intent(Intent.ACTION_PICK, MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
i.setType("image/*");
startActivityForResult(i, Constants.VALUE_BROWSE_IMAGE_REQUEST);

This will open the gallery in your phone to browse for an image. Declare a variable at the top of your activity:

private Bitmap mBitmap;

After you choose the image you want to upload from your gallery, write this code:

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);

    if (requestCode == Constants.VALUE_BROWSE_IMAGE_REQUEST &&
            resultCode == RESULT_OK &&
            data != null) {

        try {
            // Get the photo URI data
            Uri filePath = data.getData();

            // Get the Bitmap from Gallery
            mBitmap = decodeBitmap(filePath, this);
        } catch (IOException e) {
            Toast.makeText(this, "Could not open picture.", Toast.LENGTH_SHORT).show();
        }
    }
}

Now that you have the bitmap of the chosen image, you need to convert that bitmap into base64 string so that Volley can be able to upload it:

// Before uploading the selected image to the server, we need to convert the Bitmap to String.
// This method will convert Bitmap to base64 String.
private String getStringImage(Bitmap bmp) {
    ByteArrayOutputStream b = new ByteArrayOutputStream();

    // This part handles the image compression. Keep the image quality
    // at 70-90 so you don't cause lag when loading it on android
    // (0-low quality but fast load, 100-best (original) quality but slow load)
    bmp.compress(Bitmap.CompressFormat.JPEG, 80, b);
    byte[] imageBytes = b.toByteArray();
    String encodedImage = Base64.encodeToString(imageBytes, Base64.DEFAULT);
    return encodedImage;
}

Finally you can start uploading the image:

private void uploadImage() {
    StringRequest stringRequest = new StringRequest(
            Request.Method.POST,
            "URL_TO_YOUR_WEB_API",
            new Response.Listener<String>() {
                @Override
                public void onResponse(String response) {

                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    Toast.makeText(getApplicationContext(), "Failed to upload image.", Toast.LENGTH_SHORT).show();
                }
            }) {
        @Override
        protected Map<String, String> getParams() throws AuthFailureError {

            // Converting Bitmap to String
            String image = getStringImage(mBitmap);

            // Create parameters
            Map<String, String> params = new Hashtable<>();

            // Add parameters
            params.put("action", "YOUR_BACKEND_KEY1");
            params.put("...", image);

            // Returning parameters
            return params;
        }
    };

    // Creating a Request Queue
    RequestQueue requestQueue = Volley.newRequestQueue(this);

    // Adding request to the queue
    requestQueue.add(stringRequest);
}

Make sure to replace the parameter strings with however you have created your backend in php.

Example URL:

http://yoursite.com/api.php?action=uploadimage&imagebase=adwtgiuewohnjsoiu&caption=somecaptiontext

Then the parameters in android would be:

params.put("action", "uploadimage");
params.put("imagebase", image);
params.put("caption", "somecaptiontext");