如何在android中的URL中附加值编码的base64字符串

Question

在URL中附加编码的base64字符串值时，我得到NULL值。

    public void onActivityResult ( int requestCode, int resultCode, Intent data){

    if (requestCode == CAMERA_REQUEST && resultCode == Activity.RESULT_OK) {
        Uri imageUri = data.getData();
        imageView.setImageURI(imageUri);
        imageView.buildDrawingCache();
        Bitmap bmap = imageView.getDrawingCache();
        bitmapToBase64(bmap);

    } else if (requestCode == RESULT_LOAD_IMAGE && resultCode == RESULT_OK ) {
        Uri imageUri = data.getData();
        imageView.setImageURI(imageUri);
        imageView.buildDrawingCache();
        Bitmap bmap = imageView.getDrawingCache();
        bitmapToBase64(bmap);

        //Bitmap image = (Bitmap) data.getExtras().get("data");

    }
}

public String bitmapToBase64(Bitmap bitmap) {

    ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
    bitmap.compress(Bitmap.CompressFormat.JPEG, 70, byteArrayOutputStream);
    byte[] byteArray = byteArrayOutputStream.toByteArray();
    String encoderes = Base64.encodeToString(byteArray, Base64.DEFAULT);
    encodestr.setText(encoderes);

    return encoderes;
}

上面的代码是将图像编码为base64字符串但在附加到URL时，字符串变量encoderes显示为null

url="http://10.0.2.2/newz/newz/Mobile_api/photo_decode?photo_encode="+encoderes";