[url]http://ben-bai.blogspot.jp/2012/08/java-convert-image-to-base64-string-and.html[/url]

package test;

import java.io.IOException;

import sun.misc.BASE64Encoder;
import sun.misc.BASE64Decoder;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.awt.image.BufferedImage;
import javax.imageio.ImageIO;

public class ImageUtils {

/**
* Decode string to image
* @param imageString The string to decode
* @return decoded image
*/
public static BufferedImage decodeToImage(String imageString) {

BufferedImage image = null;
byte[] imageByte;
try {
BASE64Decoder decoder = new BASE64Decoder();
imageByte = decoder.decodeBuffer(imageString);
ByteArrayInputStream bis = new ByteArrayInputStream(imageByte);
image = ImageIO.read(bis);
bis.close();
} catch (Exception e) {
e.printStackTrace();
}
return image;
}

/**
* Encode image to string
* @param image The image to encode
* @param type jpeg, bmp, ...
* @return encoded string
*/
public static String encodeToString(BufferedImage image, String type) {
String imageString = null;
ByteArrayOutputStream bos = new ByteArrayOutputStream();

try {
ImageIO.write(image, type, bos);
byte[] imageBytes = bos.toByteArray();

BASE64Encoder encoder = new BASE64Encoder();
imageString = encoder.encode(imageBytes);

bos.close();
} catch (IOException e) {
e.printStackTrace();
}
return imageString;
}

public static void main (String args[]) throws IOException {
/* Test image to string and string to image start */
BufferedImage img = ImageIO.read(new File("files/img/TestImage.png"));
BufferedImage newImg;
String imgstr;
imgstr = encodeToString(img, "png");
System.out.println(imgstr);
newImg = decodeToImage(imgstr);
ImageIO.write(newImg, "png", new File("files/img/CopyOfTestImage.png"));
/* Test image to string and string to image finish */
}
}