Convert base64 string to image
This assumes a few things, that you know what the output file name will be and that your data comes as a string. I'm sure you can modify the following to meet your needs:
// Needed Imports
import java.io.ByteArrayInputStream;
import sun.misc.BASE64Decoder;
def sourceData = 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAPAAAADwCAYAAAA+VemSAAAgAEl...==';
// tokenize the data
def parts = sourceData.tokenize(",");
def imageString = parts[1];
// create a buffered image
BufferedImage image = null;
byte[] imageByte;
BASE64Decoder decoder = new BASE64Decoder();
imageByte = decoder.decodeBuffer(imageString);
ByteArrayInputStream bis = new ByteArrayInputStream(imageByte);
image = ImageIO.read(bis);
bis.close();
// write the image to a file
File outputfile = new File("image.png");
ImageIO.write(image, "png", outputfile);
Please note, this is just an example of what parts are involved. I haven't optimized this code at all and it's written off the top of my head.
In the server, do something like this:
Suppose
String data = 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAPAAAADwCAYAAAA+VemSAAAgAEl...=='
Then:
String base64Image = data.split(",")[1];
byte[] imageBytes = javax.xml.bind.DatatypeConverter.parseBase64Binary(base64Image);
Then you can do whatever you like with the bytes like:
BufferedImage img = ImageIO.read(new ByteArrayInputStream(imageBytes));