How to get a BufferedImage from a SVG?

A very easy way is to use the TwelveMonkeys lib which adds additional image type support to java's ImageIO

So for example you just add these to your maven (or copy the needed jars):

    <dependency>
        <groupId>com.twelvemonkeys.imageio</groupId>
        <artifactId>imageio-batik</artifactId> <!-- svg -->
        <version>3.2.1</version>
    </dependency>
    <dependency>
        <groupId>batik</groupId>
        <artifactId>batik-transcoder</artifactId>
        <version>1.6-1</version>
    </dependency>

And then you just read it with

BufferedImage image = ImageIO.read(svg-file);

To check if the svg reader is registered correctly you could print out the image readers:

Iterator<ImageReader> readers = ImageIO.getImageReadersByFormatName("SVG");
while (readers.hasNext()) {
    System.out.println("reader: " + readers.next());
}

The lib also supports additional params, see readme on github.

Using Batik, something like this:

public static BufferedImage rasterize(File svgFile) throws IOException {

    final BufferedImage[] imagePointer = new BufferedImage[1];

    // Rendering hints can't be set programatically, so
    // we override defaults with a temporary stylesheet.
    // These defaults emphasize quality and precision, and
    // are more similar to the defaults of other SVG viewers.
    // SVG documents can still override these defaults.
    String css = "svg {" +
            "shape-rendering: geometricPrecision;" +
            "text-rendering:  geometricPrecision;" +
            "color-rendering: optimizeQuality;" +
            "image-rendering: optimizeQuality;" +
            "}";
    File cssFile = File.createTempFile("batik-default-override-", ".css");
    FileUtils.writeStringToFile(cssFile, css);

    TranscodingHints transcoderHints = new TranscodingHints();
    transcoderHints.put(ImageTranscoder.KEY_XML_PARSER_VALIDATING, Boolean.FALSE);
    transcoderHints.put(ImageTranscoder.KEY_DOM_IMPLEMENTATION,
            SVGDOMImplementation.getDOMImplementation());
    transcoderHints.put(ImageTranscoder.KEY_DOCUMENT_ELEMENT_NAMESPACE_URI,
            SVGConstants.SVG_NAMESPACE_URI);
    transcoderHints.put(ImageTranscoder.KEY_DOCUMENT_ELEMENT, "svg");
    transcoderHints.put(ImageTranscoder.KEY_USER_STYLESHEET_URI, cssFile.toURI().toString());

    try {

        TranscoderInput input = new TranscoderInput(new FileInputStream(svgFile));

        ImageTranscoder t = new ImageTranscoder() {

            @Override
            public BufferedImage createImage(int w, int h) {
                return new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);
            }

            @Override
            public void writeImage(BufferedImage image, TranscoderOutput out)
                    throws TranscoderException {
                imagePointer[0] = image;
            }
        };
        t.setTranscodingHints(transcoderHints);
        t.transcode(input, null);
    }
    catch (TranscoderException ex) {
        // Requires Java 6
        ex.printStackTrace();
        throw new IOException("Couldn't convert " + svgFile);
    }
    finally {
        cssFile.delete();
    }

    return imagePointer[0];
}