Java - de base64 a imagen

File.WriteAllBytes("RutaArchivoImagen", Convert.FromBase64String("CadenaBase64"));

using System;

using System.IO;

namespace PruebaConsola

{

   public class MainClass

   {

      public static void Main(string[] args)

      {

         var src = "data:image/jpeg;base64,/9j/4AAQSkZJRg ... FD+EINWEUlLN14fu3zSlgxcJDmfP8MMg1IS7KQnv/iH/2Q==";

         var imagen = src.Split(';');

         File.WriteAllBytes("C:\\Prueba" + (imagen[0].IndexOf("png") >= 0 ? ".png" : ".jpg"), Convert.FromBase64String(imagen[1].Substring(7)));

      }

   }

}

import java.io.IOException;

import java.nio.file.Files;

import java.nio.file.Paths;

import java.util.Base64;

/* */

public class B64 {

	/* */

	public static void main(String args[]) throws IOException {

		byte src[] = Files.readAllBytes(Paths.get("/tmp", "1.jpg"));

		byte dst[] = Base64.getEncoder().encode(src);

		// Test System.out.println(new String(dst));

		byte trans[] = Base64.getDecoder().decode(dst);

		Files.write(Paths.get("/tmp/1_new.jpg"), trans);

	}

}