File to Base64 encoder/decoder

Question

I am trying to make a file converter that converts any file to a Base64 String that gets saved to a .txt file. To avoid too high memory usage when decoding/encoding I am using a buffer that reads the file in small chunks.

import java.io.*;
import java.nio.file.Paths;
import java.nio.file.Files;
import java.util.Base64;
import java.util.Base64.Encoder;
import java.util.Base64.Decoder;
public class Fileconverter {
  static long CHUNK_SIZE = (long) Math.pow(2, 10);
  public static void encode(String path){
    try {
      File inputFile = new File(path);
      File outputFile = new File("tmp.txt");

      FileInputStream fis = new FileInputStream(inputFile);
      FileOutputStream fos = new FileOutputStream(outputFile);

      Encoder encoder = Base64.getEncoder().withoutPadding();

      long file_len = inputFile.length();
      long filesize = inputFile.length();

      while(file_len > 0) {
        byte[] buf = new byte[(int)Math.min(file_len, CHUNK_SIZE)];
        file_len-=fis.read(buf);
        fos.write(encoder.encode(buf));
        System.out.print("\rProcessing: "+Math.round((((file_len*1.0/filesize*1.0)*100)-100)*(-1))+"% ");
      }
      fis.close();
      fos.close();
    }
    catch (Exception e) {
      e.printStackTrace();
    } 
  }
  public static void decode(String pName){
    try {
      File inputFile = new File("tmp.txt");
      File outputFile = new File(pName);

      FileInputStream fis = new FileInputStream(inputFile);
      FileOutputStream fos = new FileOutputStream(outputFile);

      Decoder decoder = Base64.getDecoder();

      long file_len = inputFile.length();
      long filesize = inputFile.length();

      while(file_len > 0) {
        byte[] buf = new byte[(int) Math.min(file_len, CHUNK_SIZE)];
        file_len-=fis.read(buf);
        fos.write(decoder.decode(buf));
        System.out.print("\rProcessing: "+Math.round((((file_len*1.0/filesize*1.0)*100)-100)*(-1))+"% ");
      }
      fis.close();
      fos.close();
    }
    catch (Exception e) {
      e.printStackTrace();  
    }
  }      
}  

The problem is that as soon as the input file requires multiple buffers to get read, it comes out corrupted and I don't know why.

Answer 1

You don't need to do all that. Java IO will handle all that for you with sane defaults. I haven't been through your code with a fine-toothed comb, but the error will most probably have been introduced with the unnecessary complexity. It has to be said that if you're only comfortable with allocating a buffer of up to 1KiB, then you're probably working in the wrong language - Java isn't known for its memory economy.

    public static void encodeToBase64(String inputPath, String outputPath) {
        Encoder encoder = Base64.getEncoder().withoutPadding();
        try (InputStream in = Files.newInputStream(Path.of(inputPath));
                OutputStream out = encoder.wrap(Files.newOutputStream(Path.of(outputPath)))) {
            in.transferTo(out);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }