Convert Image to String and String to Image in Java

In this tutorial, we are going to explain how to convert/transform Image into Base64 String and convert/transform Base64 String back to Image without compromising a Image data.  I will be using Apache Commons Codec library to achieve the ‘Convert Image to String and String to Image in Java’.

Class: org.apache.commons.codec.binary.Base64

Methods: Base64 class has overloaded methods

• Base64.encodeBase64URLSafeString – accepts byte array and converts into Base64 String.
• Base64.decodeBase64 – accepts Base64 String and converts into byte array.

How to do step by step?

Step 1 :

Preparing a byte array from image.  Typically achieved in following ways:

• During File upload – at server side application will be receiving a file data as byte stream.
• Reading a image file from File System as byte stream.

Step 2 :

Once we have byte array of Image file, apply below method to convert byte array into Base64 string.  Here even though string is not used in URL param, consider using URL safe Base 64 string.  The url-safe variation emits - and _ instead of + and / characters.

Method signature:
public static String encodeBase64URLSafeString(byte[] binaryData)
 
Usage:
String imageDataString = Base64.encodeBase64URLSafeString(imageByteArray)

Step 3 :

At receiving end; we will be receiving a Base64 String of Image data, apply below method to covert Base64 String into byte array

Method signature:
public static byte[]  decodeBase64(String base64String)
 
Usage:
byte[] imageDataBytes = Base64.decodeBase64(imageDataString)

Step 4 :

We have imageDataBytes byte array, write this stream as file in the File system

Complete Source Code : 

package com.myjeeva.image;
 
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
 
import org.apache.commons.codec.binary.Base64;
 
/**
 * @desc Image manipulation - Conversion
 * 
 * @filename ImageManipulation.java
 * @author Jeevanandam M. (jeeva@myjeeva.com)
 * @copyright myjeeva.com
 */
public class ImageManipulation {
 
    public static void main(String[] args) {
 
        File file = new File("/Users/jeeva/Pictures/wallpapers/water-drop.jpg");
 
        try {            
            // Reading a Image file from file system
            FileInputStream imageInFile = new FileInputStream(file);
            byte imageData[] = new byte[(int) file.length()];
            imageInFile.read(imageData);
 
            // Converting Image byte array into Base64 String
            String imageDataString = encodeImage(imageData);
 
            // Converting a Base64 String into Image byte array
            byte[] imageByteArray = decodeImage(imageDataString);
 
            // Write a image byte array into file system
            FileOutputStream imageOutFile = new FileOutputStream(
                    "/Users/jeeva/Pictures/wallpapers/water-drop-after-convert.jpg");
 
            imageOutFile.write(imageByteArray);
 
            imageInFile.close();
            imageOutFile.close();
 
            System.out.println("Image Successfully Manipulated!");
        } catch (FileNotFoundException e) {
            System.out.println("Image not found" + e);
        } catch (IOException ioe) {
            System.out.println("Exception while reading the Image " + ioe);
        }
    }
 
    /**
     * Encodes the byte array into base64 string
     *
     * @param imageByteArray - byte array
     * @return String a {@link java.lang.String}
     */
    public static String encodeImage(byte[] imageByteArray) {
        return Base64.encodeBase64URLSafeString(imageByteArray);
    }
 
    /**
     * Decodes the base64 string into byte array
     *
     * @param imageDataString - a {@link java.lang.String}
     * @return byte array
     */
    public static byte[] decodeImage(String imageDataString) {
        return Base64.decodeBase64(imageDataString);
    }
}

Above source code help you to Convert Image to String and String to Image in Java.