Base64 Java encode and decode a string

Question

I want to encode a string into base64 and transfer it through a socket and decode it back.

But after decoding it gives different answer.

Following is my code and result is "77+9x6s="

import javax.xml.bind.DatatypeConverter;

    public class f{

       public static void main(String a[]){

          String str = new String(DatatypeConverter.parseBase64Binary("user:123"));
          String res = DatatypeConverter.printBase64Binary(str.getBytes());
          System.out.println(res);
       }
    }

Any idea about how to implement this?

see http://stackoverflow.com/questions/13109588/base64-encoding-in-java — Frederic Close, Nov 02 '13 at 16:06
`DataTypeConverter` works just fine, the original poster has just mixed the order. It should look like this: `String str = DatatypeConverter.printBase64Binary("user:123".getBytes());` `String res = new String(DatatypeConverter.parseBase64Binary(str));` — mrts, Sep 12 '16 at 14:42
parseBase64Binary() is used for decoding and printBase64Binary() is used for encoding. — sagar vyas, Feb 18 '21 at 06:33

score 272 · Accepted Answer · edited Feb 07 '19 at 14:39

272

You can use following approach:

import org.apache.commons.codec.binary.Base64;

// Encode data on your side using BASE64
byte[] bytesEncoded = Base64.encodeBase64(str.getBytes());
System.out.println("encoded value is " + new String(bytesEncoded));

// Decode data on other side, by processing encoded data
byte[] valueDecoded = Base64.decodeBase64(bytesEncoded);
System.out.println("Decoded value is " + new String(valueDecoded));

Hope this answers your doubt.

edited Feb 07 '19 at 14:39

leaqui

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answered Nov 02 '13 at 16:09

Dark Knight

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I get `The method encodeBase64(byte[]) is undefined for the type Base64` – Francisco Corrales Morales May 27 '14 at 21:31
2

This one is better http://stackoverflow.com/a/13862852/2615737 – Francisco Corrales Morales May 27 '14 at 22:13
1

String str =Base64.encodeToString(strFinalXML.getBytes(), 0); //For java 1.7 + – Abhijit Gujar Apr 06 '15 at 13:42
please specify the version of Java for this solution, as new functionality was given to Java 8 but it was diffrent in 6 & 7. – Omar Ayala May 26 '16 at 17:11
Which Base64 library did you use? There are many. – Matt Pennington Aug 24 '16 at 04:19
2

@FranciscoCorralesMorales He's using org.apache.commons.codec.binary.Base64 – RavenMan Sep 23 '16 at 22:49
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This answer is somewhat confusing when using Java 8 as this now includes a Base64 class but does not have the method "encodeBase64". The library that this answer is using is not stated in the answer. If you are using Java 8+ then better to follow this answer: https://stackoverflow.com/a/28305759/236587 – Rupert Madden-Abbott Nov 28 '17 at 12:12
2

@RupertMadden-Abbott encodeBase64 is not available under package java.util.Base64. To have above code working, You have to import Base64 from org.apache.commons.codec.binary.Base64 – ChandraBhan Singh Jun 19 '18 at 06:52

score 160 · Answer 2 · edited Jun 03 '15 at 00:31

160

Java 8 now supports BASE64 Encoding and Decoding. You can use the following classes: java.util.Base64, java.util.Base64.Encoder and java.util.Base64.Decoder.

Example usage:

// encode with padding
String encoded = Base64.getEncoder().encodeToString(someByteArray);

// encode without padding
String encoded = Base64.getEncoder().withoutPadding().encodeToString(someByteArray);

// decode a String
byte [] barr = Base64.getDecoder().decode(encoded);

edited Jun 03 '15 at 00:31

dschulz

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answered Feb 03 '15 at 18:06

Lakshma Gopidi

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When to use with padding vs without padding?? – IgorGanapolsky Feb 11 '16 at 17:00
5

Take care when switching from apache to java 8: org.apache.commons.codec.binary.Base64.decodeBase64 also accepts mime encoded input, but java.util.Base64.getDecoder not. If you also want to decode mime encoded you need to use java.util.Base64.getMimeDecoder. – wdk Dec 12 '16 at 12:08
2

@IgorGanapolsky here is the anwer to what is padding? https://stackoverflow.com/questions/4080988/why-does-base64-encoding-require-padding-if-the-input-length-is-not-divisible-by It has to do with filling the String with 0 bytes if its odd – Khan Oct 01 '18 at 20:54

score 60 · Answer 3 · edited Nov 20 '19 at 09:17

The accepted answer uses the Apache Commons package but this is how I did it using Java's native libraries

Java 11 and up

import java.util.Base64;

public class Base64Encoding {

    public static void main(String[] args) {
        Base64.Encoder enc = Base64.getEncoder();
        Base64.Decoder dec = Base64.getDecoder();
        String str = "77+9x6s=";

        // encode data using BASE64
        String encoded = enc.encodeToString(str.getBytes());
        System.out.println("encoded value is \t" + encoded);

        // Decode data
        String decoded = new String(dec.decode(encoded));
        System.out.println("decoded value is \t" + decoded);
        System.out.println("original value is \t" + str);
    }
}

Java 6 - 10

import java.io.UnsupportedEncodingException;    
import javax.xml.bind.DatatypeConverter;

public class EncodeString64 {
    public static void main(String[] args) throws UnsupportedEncodingException {

        String str = "77+9x6s=";
        // encode data using BASE64
        String encoded = DatatypeConverter.printBase64Binary(str.getBytes());
        System.out.println("encoded value is \t" + encoded);

        // Decode data 
        String decoded = new String(DatatypeConverter.parseBase64Binary(encoded));
        System.out.println("decoded value is \t" + decoded);

        System.out.println("original value is \t" + str);
    }
}

The better way would be to try/catch the encoding/decoding steps but hopefully you get the idea.

Note that this will not work on Android. – Mavamaarten Nov 14 '16 at 10:48 — Mavamaarten, Nov 14 '16 at 10:48
Note that javax.xml.bind (JAXB) is removed in Java 11. – Dennie May 23 '19 at 08:15 — Dennie, May 23 '19 at 08:15
`java.util.Base64` is available starting Java 8, not 11. – Isaac Feb 10 '20 at 14:46 — Isaac, Feb 10 '20 at 14:46

score 28 · Answer 4 · answered Oct 23 '14 at 14:38

For Spring Users , Spring Security has a Base64 class in the org.springframework.security.crypto.codec package that can also be used for encoding and decoding of Base64. Ex.

 public static String base64Encode(String token) {
    byte[] encodedBytes = Base64.encode(token.getBytes());
    return new String(encodedBytes, Charset.forName("UTF-8"));
}


public static String base64Decode(String token) {
    byte[] decodedBytes = Base64.decode(token.getBytes());
    return new String(decodedBytes, Charset.forName("UTF-8"));
}

For those of you who are looking this now 'org.springframework.security.crypto.codec.Base64' is deprecated — Samakaab, Dec 16 '21 at 17:55

score 23 · Answer 5 · edited Jun 27 '16 at 08:35

23

The following is a good solution -

import android.util.Base64;

String converted = Base64.encodeToString(toConvert.toString().getBytes(), Base64.DEFAULT);

String stringFromBase = new String(Base64.decode(converted, Base64.DEFAULT));

That's it. A single line encoding and decoding.

edited Jun 27 '16 at 08:35

Gandalf the White

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answered May 19 '14 at 14:59

Yehonatan

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it is renamed to java.util.Base64. – eastwater Aug 20 '18 at 23:51
great solution without any libraries! – Aziz Yokubjonov Mar 23 '20 at 16:41

score 8 · Answer 6 · answered Mar 12 '15 at 07:55

import javax.xml.bind.DatatypeConverter;

public class f{

   public static void main(String a[]){

      String str = new String(DatatypeConverter.printBase64Binary(new String("user:123").getBytes()));
      String res = DatatypeConverter.parseBase64Binary(str);
      System.out.println(res);
   }
}

Base64 Java encode and decode a string

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