How can I convert an image into a Base64 string?

Question

What is the code to transform an image (maximum of 200 KB) into a Base64 String?

I need to know how to do it with Android, because I have to add the functionali

Answer 1

If you need Base64 over JSON, check out Jackson: it has explicit support for binary data read/write as Base64 at both the low level (JsonParser, JsonGenerator) and data-binding level. So you can just have POJOs with byte[] properties, and encoding/decoding is automatically handled.

And pretty efficiently too, should that matter.

Answer 2

For those looking for an efficient method to convert an image file to a Base64 string without compression or converting the file to a bitmap first, you can instead encode the file as base64

val base64EncodedImage = FileInputStream(imageItem.localSrc).use {inputStream - >
    ByteArrayOutputStream().use {outputStream - >
            Base64OutputStream(outputStream, Base64.DEFAULT).use {
                base64FilterStream - >
                    inputStream.copyTo(base64FilterStream)
                base64FilterStream.flush()
                outputStream.toString()
            }
      }
}

Hope this helps!

Answer 3

Here is the encoding and decoding code in Kotlin:

 fun encode(imageUri: Uri): String {
    val input = activity.getContentResolver().openInputStream(imageUri)
    val image = BitmapFactory.decodeStream(input , null, null)

    // Encode image to base64 string
    val baos = ByteArrayOutputStream()
    image.compress(Bitmap.CompressFormat.JPEG, 100, baos)
    var imageBytes = baos.toByteArray()
    val imageString = Base64.encodeToString(imageBytes, Base64.DEFAULT)
    return imageString
}

fun decode(imageString: String) {

    // Decode base64 string to image
    val imageBytes = Base64.decode(imageString, Base64.DEFAULT)
    val decodedImage = BitmapFactory.decodeByteArray(imageBytes, 0, imageBytes.size)

    imageview.setImageBitmap(decodedImage)
}

Answer 4

// Put the image file path into this method
public static String getFileToByte(String filePath){
    Bitmap bmp = null;
    ByteArrayOutputStream bos = null;
    byte[] bt = null;
    String encodeString = null;
    try{
        bmp = BitmapFactory.decodeFile(filePath);
        bos = new ByteArrayOutputStream();
        bmp.compress(Bitmap.CompressFormat.JPEG, 100, bos);
        bt = bos.toByteArray();
        encodeString = Base64.encodeToString(bt, Base64.DEFAULT);
    }
    catch (Exception e){
      e.printStackTrace();
    }
    return encodeString;
}

Answer 5

Instead of using Bitmap, you can also do this through a trivial InputStream. Well, I am not sure, but I think it's a bit efficient.

InputStream inputStream = new FileInputStream(fileName); // You can get an inputStream using any I/O API
byte[] bytes;
byte[] buffer = new byte[8192];
int bytesRead;
ByteArrayOutputStream output = new ByteArrayOutputStream();

try {
    while ((bytesRead = inputStream.read(buffer)) != -1) {
        output.write(buffer, 0, bytesRead);
    }
}
catch (IOException e) {
    e.printStackTrace();
}

bytes = output.toByteArray();
String encodedString = Base64.encodeToString(bytes, Base64.DEFAULT);

Answer 6

Below is the pseudocode that may help you:

public  String getBase64FromFile(String path)
{
    Bitmap bmp = null;
    ByteArrayOutputStream baos = null;
    byte[] baat = null;
    String encodeString = null;
    try
    {
        bmp = BitmapFactory.decodeFile(path);
        baos = new ByteArrayOutputStream();
        bmp.compress(Bitmap.CompressFormat.JPEG, 100, baos);
        baat = baos.toByteArray();
        encodeString = Base64.encodeToString(baat, Base64.DEFAULT);
    }
    catch (Exception e)
    {
        e.printStackTrace();
    }

   return encodeString;
}