Adam T's blog: Life in the FAST lane

I'm calling an AccuWeather service to get a short-range forecast for a given location. In the reply, there's a small two-digit numerical element which refers to the icon which represents that day's weather. I need to take that icon and base64 encode it before sending it out of Java CAPS.

You can fetch the relevant image by constructing a URL quite easily but obviously I don't want to be doing this too often and I'd prefer to have a local cache of those images. But how to access them from a java collaboration?

The solution is simple when you know how to do it - it took a fair amount of searching (and a stupid bug of my own making) before I came up with an answer.

1. Have all your images in a directory, then create a jar file with the contents of that directory. Mine are named 01.gif, 02.gif, ... and so on.
2. Import the jar into your java collaboration.
3. Access the image you need using getResourceAsStream().
4. Read the bytestream.
5. Perform the Base64 encoding.

java.io.BufferedInputStream is = new java.io.BufferedInputStream(
            this.getClass().getResourceAsStream( "/WeatherImages/" +
                                                 iconNum +
                                                 ".gif" ) );
if (is != null) {
    java.io.ByteArrayOutputStream bos = new java.io.ByteArrayOutputStream();
    byte[] buf = new byte[1024];
    int bytesRead = 0;
    while ((bytesRead = is.read( buf, 0, buf.length )) > 0) {
        bos.write( buf, 0, bytesRead );
    }
    sun.misc.BASE64Encoder encoder = new sun.misc.BASE64Encoder();
    String iconEncoded = encoder.encode( bos.toByteArray() );
    // Next line removes CRLFs which mobility pack Base64 decoder
    // doesn't seem to like    
    iconEncoded = iconEncoded.replaceAll( "\r|\n", "" );
    output.getForecastResponseType().getForecast( i1 ).setIcon( iconEncoded );
    is.close();
}