Converting a Base64 encoded String to an Image

[Carl Jenkins]

Hey all!

I am having a bit of difficulty here I was hoping someone could help me out with.

As the subject line states - I am basically trying to take a Base64 encoded string and decode it then turn in into an PNG image.
Problem is I keep just getting an empty file.

         String value= "Wyk+HjAxHTAyNzg3MDUdODQwHTAxOR0wMDAwMDAwMDAwMDAwMDAd" +
"RkRFQh0wMDAwMDAwHTA0MB0dMS8xHTUwLjVMQh1OHVcgMzR0aCBTdHJlZXQdQ" +
"XVzdGluHVRYHSAeMDYdMTBaR0QwMDQdMTFaUmVjaXBpZW50IENvbXBhbnkgTmFt" +
"ZR0xMlo5MDEyNjM3OTA2HTE0WioqVEVTVCBMQUJFTCAtIERPIE5PVCBTSElQKio" +
"dMjNaTh0yMlocWR0yMFogHDAdMjZaNjEzMxwdHgQ=";

        BASE64Decoder decoder = new BASE64Decoder();
        byte[] imgBytes = decoder.decodeBuffer(value);        

       BufferedImage bufImg = ImageIO.read(new ByteArrayInputStream(imgBytes));
       File imgOutFile = new File("newLabel.png");
    ImageIO.write(bufImg, "png", imgOutFile);   

Any help would be fantastic! Thanks!

[Wouter Oet]

From which library is the BASE64Decoder class?

[Carl Jenkins]

I tried the apache Base64 and the sun.misc.BASE64Decoder.

But, got the same results from both..

[Ernesto Chicas]

Try this

 
byte[] btDataFile = new sun.misc.BASE64Decoder().decodeBuffer(youtData);
File of = new File("yourFile.png");
FileOutputStream osf = new FileOutputStream(of);
osf.write(btDataFile);
osf.flush();

[Wouter Oet]

Are you sure that you're getting an empty file and not a IllegalArgumentException because bufImg == null.
Because that is what I'm getting and that's because there is no ImageReader registered that can read the input.

[John de Michele]

Carl,

Packages in the sun.* hierarchy should be expressly avoided. Those are private to Sun, and there is no guarantee that they will work from one build to the next.

John.

[Ernesto Chicas]

John de Michele wrote:Carl,

Packages in the sun.* hierarchy should be expressly avoided. Those are private to Sun, and there is no guarantee that they will work from one build to the next.

John.

certainly

http://java.sun.com/products/jdk/faq/faq-sun-packages.html

[Carl Jenkins]

Hmm I still get nothing.

Just a png file and when I open it says "No preview available".

[Carl Jenkins]

Carl,

Packages in the sun.* hierarchy should be expressly avoided. Those are private to Sun, and there is no guarantee that they will work from one build to the next.

John.

Understood, but even when using the Apache libs I still get nothing...

Apache Base64

[Ernesto Chicas]

String value= "Wyk+HjAxHTAyNzg3MDUdODQwHTAxOR0wMDAwMDAwMDAwMDAwMD" +
"AdRkRFQh0wMDAwMDAwHTA0MB0dMS8xHTUwLjVMQh1OHVcgMzR0aCBTdHJlZXQdQ" +
"XVzdGluHVRYHSAeMDYdMTBaR0QwMDQdMTFaUmVjaXBpZW50IENvbXBhbnkgTmFtZR0" +
"xMlo5MDEyNjM3OTA2HTE0WioqVEVTVCBMQUJFTCAtIERPIE5PVCBTSElQKiodMjNaTh0" +
"yMlocWR0yMFogHDAdMjZaNjEzMxwdHgQ=";         
Base64 decoder = new Base64(); 
byte[] imgBytes = decoder.decode(value);
FileOutputStream osf = new FileOutputStream(new File("yourImage.png"););
osf.write(imgBytes);
osf.flush();

http://commons.apache.org/codec/apidocs/org/apache/commons/codec/binary/Base64.html

[Carl Jenkins]

1. String value= "Wyk+HjAxHTAyNzg3MDUdODQwHTAxOR0wMDAwMDAwMDAwMDAwMD
AdRkRFQh0wMDAwMDAwHTA0MB0dMS8xHTUwLjVMQh1OHVcgMzR0aCBTdHJlZXQdQXVzdGluHV
RYHSAeMDYdMTBaR0QwMDQdMTFaUmVjaXBpZW50IENvbXBhbnkgTmFtZR0xMlo5MDEyNjM3OTA
2HTE0WioqVEVTVCBMQUJFTCAtIERPIE5PVCBTSElQKiodMjNaTh0yMlocWR0yMFogHDAdMjZaNjEzMxwdHgQ=";
2. Base64 decoder = new Base64();
3. byte[] imgBytes = decoder.decode(value);
4. FileOutputStream osf = new FileOutputStream(new File("yourImage.png"););
5. osf.write(imgBytes);
6. osf.flush();

http://commons.apache.org/codec/apidocs/org/apache...mmons/codec/binary/Base64.html

I tried the apache codes as well.
Certainly, appreciate the help, but this just isn't working for some reason.

[Wouter Oet]

You are aware that PNG has a certain structure and if you just decode the String then the output doesn't match that structure?

[Henry Wong]

Agreed. Its not a PNG file. Just ran the program and examined the saved file.

Its a text file. With something related to a company in Austin Texas.

Henry

[Ernesto Chicas]

Henry Wong wrote:
Agreed. Its not a PNG file. Just ran the program and examined the saved file.

Its a text file. With something related to a company in Austin Texas.

Henry

Is correct, the String is not an image....

I got the following:
[)>010278705840019000000000000000FDEB00000000401/150.5LBNW 34th StreetAustinTX ........................................................

Greetings!

[Deepak Mula]

Try This:

[i]/**
     * Decodes a byte array from Base64 format.
     * 
     * @param s
     *            a Base64 String to be decoded.
     * @return An array containing the decoded data bytes.
     * @throws IllegalArgumentException
     *             if the input is not valid Base64 encoded data.
     */
    public static byte[] decode(String s)
    {
        return decode(s.toCharArray());
    }

    /**
     * Decodes a byte array from Base64 format. No blanks or line breaks are
     * allowed within the Base64 encoded data.
     * 
     * @param in
     *            a character array containing the Base64 encoded data.
     * @return An array containing the decoded data bytes.
     * @throws IllegalArgumentException
     *             if the input is not valid Base64 encoded data.
     */
    public static byte[] decode(char[] in)
    {
        int iLen = in.length;
        if (iLen % 4 != 0)
            throw new IllegalArgumentException(
            "Length of Base64 encoded input string is not a multiple of 4.");
        while (iLen > 0 && in[iLen - 1] == '=')
            iLen--;
        int oLen = (iLen * 3) / 4;
        byte[] out = new byte[oLen];
        int ip = 0;
        int op = 0;
        while (ip < iLen)
        {
            int i0 = in[ip++];
            int i1 = in[ip++];
            int i2 = ip < iLen ? in[ip++] : 'A';
            int i3 = ip < iLen ? in[ip++] : 'A';
            if (i0 > 127 || i1 > 127 || i2 > 127 || i3 > 127)
                throw new IllegalArgumentException(
                "Illegal character in Base64 encoded data.");
            int b0 = map2[i0];
            int b1 = map2[i1];
            int b2 = map2[i2];
            int b3 = map2[i3];
            if (b0 < 0 || b1 < 0 || b2 < 0 || b3 < 0)
                throw new IllegalArgumentException(
                "Illegal character in Base64 encoded data.");
            int o0 = (b0 << 2) | (b1 >>> 4);
            int o1 = ((b1 & 0xf) << 4) | (b2 >>> 2);
            int o2 = ((b2 & 3) << 6) | b3;
            out[op++] = (byte) o0;
            if (op < oLen)
                out[op++] = (byte) o1;
            if (op < oLen)
                out[op++] = (byte) o2;
        }
        return out;
    }[/i]

the above method decodes Base64 String to bytes image.

[Jesper de Jong]

Hanuma, did you write that code yourself? If not, then give credit to the person who did - QuoteYourSources. Also, please UseCodeTags when you post source code.

[Deepak Mula]

Yes, I have written this code in one of my projects.

[Tope Kolawole]

Please can you show add how came about the variable "map2" because the code is not compiling

[Deepak Mula]

I have some class level variables for map1 and map2, please see below:

 private static char[] map1 = new char[64];
    static
    {
        int i = 0;
        for (char c = 'A'; c <= 'Z'; c++)
            map1[i++] = c;
        for (char c = 'a'; c <= 'z'; c++)
            map1[i++] = c;
        for (char c = '0'; c <= '9'; c++)
            map1[i++] = c;
        map1[i++] = '+';
        map1[i++] = '/';
    }

    // Mapping table from Base64 characters to 6-bit nibbles.
    private static byte[] map2 = new byte[128];
    static
    {
        for (int i = 0; i < map2.length; i++)
            map2[i] = -1;
        for (int i = 0; i < 64; i++)
            map2[map1[i]] = (byte) i;
    }

[Tope Kolawole]

Than you very much it saves my ass

[Emmanuel Oluwagbemi]

....and my ass too!

[Emmanuel Oluwagbemi]

I find something else though.

String data = "HFhjkkHjhFUgHJ......"; //Your base64 string
BASE64Decoder bd = new BASE64Decoder();
byte[] buffer = bd.decodeBuffer(data);

equally gets the conversion done. The fully qualified name of the class is sun.misc.BASE64Decoder and it 'ships' with java se (well, the Sun Oracle implementation).

For those who want to use this to convert a html dataURL to binary data (good old bytes), you'll keep getting exceptions if you try convert directly. That's because, dataURL contains some metadata (http://tools.ietf.org/html/rfc2397) before the actual data. It you print the data url, you'll see similar to:
data:image/png;base64,iVBORw0KGgoAAAA

The actual data starts after base64,

So you do this first:

int start = data.indexOf(",");
data = data.substring(start + 1);

But of course you already knew that.

[Campbell Ritchie]

I have had to break up the long lines inside the code tags because they make the whole thread difficult to read. You can see the right way to do it in the code tags and the wrong way in the quote tags.
You would have done it a lot better than me, because you would have put the " +↩" in the same places throughout.