Encoding as Base64 in Java

Question

I need to encode some data in the Base64 encoding in Java. How do I do that? What is the name of the class that provides a Base64 encoder?

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I tried to use the <

Answer 1

Eclipse gives you an error/warning because you are trying to use internal classes that are specific to a JDK vendor and not part of the public API. Jakarta Commons provides its own implementation of base64 codecs, which of course reside in a different package. Delete those imports and let Eclipse import the proper Commons classs for you.

Answer 2

To convert this, you need an encoder & decoder which you will get from Base64Coder - an open-source Base64 encoder/decoder in Java. It is file Base64Coder.java you will need.

Now to access this class as per your requirement you will need the class below:

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.InputStream;
import java.io.IOException;
import java.io.OutputStream;

public class Base64 {

    public static void main(String args[]) throws IOException {
        /*
         * if (args.length != 2) {
         *     System.out.println(
         *         "Command line parameters: inputFileName outputFileName");
         *     System.exit(9);
         * } encodeFile(args[0], args[1]);
         */
        File sourceImage = new File("back3.png");
        File sourceImage64 = new File("back3.txt");
        File destImage = new File("back4.png");
        encodeFile(sourceImage, sourceImage64);
        decodeFile(sourceImage64, destImage);
    }

    private static void encodeFile(File inputFile, File outputFile) throws IOException {
        BufferedInputStream in = null;
        BufferedWriter out = null;
        try {
            in = new BufferedInputStream(new FileInputStream(inputFile));
            out = new BufferedWriter(new FileWriter(outputFile));
            encodeStream(in, out);
            out.flush();
        }
        finally {
            if (in != null)
                in.close();
            if (out != null)
                out.close();
        }
    }

    private static void encodeStream(InputStream in, BufferedWriter out) throws IOException {
        int lineLength = 72;
        byte[] buf = new byte[lineLength / 4 * 3];
        while (true) {
            int len = in.read(buf);
            if (len <= 0)
                break;
            out.write(Base64Coder.encode(buf, 0, len));
            out.newLine();
        }
    }

    static String encodeArray(byte[] in) throws IOException {
        StringBuffer out = new StringBuffer();
        out.append(Base64Coder.encode(in, 0, in.length));
        return out.toString();
    }

    static byte[] decodeArray(String in) throws IOException {
        byte[] buf = Base64Coder.decodeLines(in);
        return buf;
    }

    private static void decodeFile(File inputFile, File outputFile) throws IOException {
        BufferedReader in = null;
        BufferedOutputStream out = null;
        try {
            in = new BufferedReader(new FileReader(inputFile));
            out = new BufferedOutputStream(new FileOutputStream(outputFile));
            decodeStream(in, out);
            out.flush();
        }
        finally {
            if (in != null)
                in.close();
            if (out != null)
                out.close();
        }
    }

    private static void decodeStream(BufferedReader in, OutputStream out) throws IOException {
        while (true) {
            String s = in.readLine();
            if (s == null)
                break;
            byte[] buf = Base64Coder.decodeLines(s);
            out.write(buf);
        }
    }
}

In Android you can convert your bitmap to Base64 for Uploading to a server or web service.

Bitmap bmImage = //Data
ByteArrayOutputStream baos = new ByteArrayOutputStream();
bmImage.compress(Bitmap.CompressFormat.JPEG, 100, baos);
byte[] imageData = baos.toByteArray();
String encodedImage = Base64.encodeArray(imageData);

This “encodedImage” is text representation of your image. You can use this for either uploading purpose or for diplaying directly into an HTML page as below (reference):

<img alt="" src="data:image/png;base64,<?php echo $encodedImage; ?>" width="100px" />
<img alt="" src="data:image/png;base64,/9j/4AAQ...........1f/9k=" width="100px" />

Documentation: http://dwij.co.in/java-base64-image-encoder

Answer 3

You need to change the import of your class:

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

And then change your class to use the Base64 class.

Here's some example code:

byte[] encodedBytes = Base64.encodeBase64("Test".getBytes());
System.out.println("encodedBytes " + new String(encodedBytes));
byte[] decodedBytes = Base64.decodeBase64(encodedBytes);
System.out.println("decodedBytes " + new String(decodedBytes));

Then read why you shouldn't use sun.* packages.

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Update (2016-12-16)

You can now use java.util.Base64 with Java 8. First, import it as you normally do:

import java.util.Base64;

Then use the Base64 static methods as follows:

byte[] encodedBytes = Base64.getEncoder().encode("Test".getBytes());
System.out.println("encodedBytes " + new String(encodedBytes));
byte[] decodedBytes = Base64.getDecoder().decode(encodedBytes);
System.out.println("decodedBytes " + new String(decodedBytes));

If you directly want to encode string and get the result as encoded string, you can use this:

String encodeBytes = Base64.getEncoder().encodeToString((userName + ":" + password).getBytes());

See Java documentation for Base64 for more.

Answer 4

Google Guava is another choice to encode and decode Base64 data:

POM configuration:

<dependency>
   <artifactId>guava</artifactId>
   <groupId>com.google.guava</groupId>
   <type>jar</type>
   <version>14.0.1</version>
</dependency>

Sample code:

String inputContent = "Hello Việt Nam";
String base64String = BaseEncoding.base64().encode(inputContent.getBytes("UTF-8"));

// Decode
System.out.println("Base64:" + base64String); // SGVsbG8gVmnhu4d0IE5hbQ==
byte[] contentInBytes = BaseEncoding.base64().decode(base64String);
System.out.println("Source content: " + new String(contentInBytes, "UTF-8")); // Hello Việt Nam

Answer 5

If you are stuck to an earlier version of Java than 8 but already using AWS SDK for Java, you can use com.amazonaws.util.Base64.