HtmlUnit use WebClient to download an image as base64 encoded DATA Uri

Question

I want to use an existing instance of WebClient to download an image. The reason for this is because I want the cookies to be passed with the request.

How can I download an image using an existing instance of WebClient?

Also, how can I base64 encode the image to be able to view it using data:image/jpeg;base64,...

Current code:

WebClient client = new WebClient(BrowserVersion.FIREFOX_3_6);
UnexpectedPage imagePage = client.getPage("http://...");
String imageString = imagePage.getWebResponse().getContentAsString();
BASE64Encoder encoder = new BASE64Encoder();
String base64data = encoder.encode(imageString.getBytes());

So now I have base64 data of the image, but I still can't view the image using data:image/jpeg;base64,....

How are you doing it now? I mean, how the existing instance `WebClient` is built (the code you are using)? — acdcjunior, Aug 04 '13 at 04:30
just assume the basic `WebClient client = new WebClient(BrowserVersion.FIREFOX_3_6);` — user2103849, Aug 04 '13 at 04:33
i think i could find the code to convert it into file, but im interested in creating a base64 string that i could view in a browser — user2103849, Aug 04 '13 at 04:40

score 2 · Accepted Answer · edited May 23 '17 at 12:31

A couple of things to consider:

The BASE64Encoder() generates a string that has a line break every 77 chars. Take that out using .replaceAll("\r?\n","").
For that method also, it is better to retrieve the web page InputStream rather than the string. Also, to convert that to a byte array, I used a utility method (source and other options can be found here).

Working source code:

public static void main (String args[]) throws IOException {
    WebClient client = new WebClient(BrowserVersion.FIREFOX_3_6);
    UnexpectedPage imagePage = client.getPage("https://i.stack.imgur.com/9DdHc.jpg");
    BASE64Encoder encoder = new BASE64Encoder();
    String base64data = encoder.encode(inputStreamToByteArray(imagePage.getWebResponse().getContentAsStream()));
    System.out.println("<img src=\"data:image/png;base64,"+base64data.replaceAll("\r?\n","")+"\" />");
}

private static byte[] inputStreamToByteArray(InputStream is) throws IOException {
    ByteArrayOutputStream buffer = new ByteArrayOutputStream();
    int nRead;
    byte[] data = new byte[16384];
    while ((nRead = is.read(data, 0, data.length)) != -1) {
        buffer.write(data, 0, nRead);
    }
    buffer.flush();
    return buffer.toByteArray();
}

Source image:

yao face

Output base64 image here.

`imagePage.getWebResponse().getContentAsString()` does not work because it tries to encode the received content as `String`, and for that it changes to `?` the bytes it can't encode. Even using `getContentAsString("base64")` changes a byte here and there, witch can completely mess the image: http://jsfiddle.net/acdcjunior/JeayD/2/ — acdcjunior, Aug 04 '13 at 05:34
yes, i figured that out. i used `image.getWebResponse().getContentAsStream()` and it worked — user2103849, Aug 04 '13 at 06:05

HtmlUnit use WebClient to download an image as base64 encoded DATA Uri

1 Answers1