The following is a very simple example using Batik to execute the onload scripts in a document and write the resulting document tree to stdout. Originally http://lists.w3.org/Archives/Public/www-archive/2005Mar/0030.html

BatikPostScriptPP.java

import java.io.OutputStreamWriter;
import org.w3c.dom.Document;
import org.apache.batik.bridge.BaseScriptingEnvironment;
import org.apache.batik.bridge.BridgeContext;
import org.apache.batik.bridge.GVTBuilder;
import org.apache.batik.bridge.UserAgentAdapter;
import org.apache.batik.transcoder.svg2svg.SVGTranscoder;
import org.apache.batik.transcoder.TranscoderInput;
import org.apache.batik.transcoder.TranscoderOutput;
import org.apache.batik.dom.svg.SAXSVGDocumentFactory;
import org.apache.batik.util.XMLResourceDescriptor;

public class BatikPostScriptPP
{
    void run() throws Exception
    {
        String parser = XMLResourceDescriptor.getXMLParserClassName();
        SAXSVGDocumentFactory f = new SAXSVGDocumentFactory(parser);
        String uri = "http://...";
        Document doc = f.createDocument(uri);

        UserAgentAdapter userAgent = new UserAgentAdapter();
        GVTBuilder builder         = new GVTBuilder();
        BridgeContext ctx          = new BridgeContext(userAgent);
        ctx.setDynamic(true);

        builder.build(ctx, doc);
        BaseScriptingEnvironment scriptEnvironment 
            = new BaseScriptingEnvironment(ctx);

        scriptEnvironment.loadScripts();
        scriptEnvironment.dispatchSVGLoadEvent();

        SVGTranscoder p       = new SVGTranscoder();
        TranscoderInput in    = new TranscoderInput(doc);
        OutputStreamWriter ow = new OutputStreamWriter(System.out);
        TranscoderOutput out  = new TranscoderOutput(ow);

        p.transcode(in, out);
    }

    public static void main(String[] args) throws Exception
    {
        (new BatikPostScriptPP()).run();
    } 
}