VisClient/org/hfbk/vis/source/Source.java

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package org.hfbk.vis.source;

import java.io.IOException;
import java.lang.reflect.Constructor;
import java.net.URL;

import org.dronus.graph.Edge;
import org.dronus.graph.Graph;
import org.dronus.graph.Node;
import org.hfbk.util.HTTPUtils;
import org.hfbk.vis.Prefs;


public abstract class Source extends Thread {
        
        
public static String baseURL;
        
        public URL url;

        public Graph graph;
        public boolean finished;
        
        protected boolean silent;
        
        int edgecount;

        String keyword; 

        public static Source getSource(String url){
                
                final Class<?>[] SIGNATURE={URL.class};
                
                Class<?> cl=null; //class of VisNode to find
                URL u=null;
                try{
                        u=new URL(url);
                        String source=getParam(new URL(url), "source");
                        
                        //build java classname
                        String classname=Character.toUpperCase(source.charAt(0))+source.substring(1);
                        if (classname.matches(":.*")) classname="Class";
                        //look up class. if it is a helper Node with no visual class, exception below. 
                        cl=Class.forName("org.hfbk.vis.source.Source"+classname);
                        //a matching visual class is found. instantiate the node. 
                        Constructor cns=cl.getConstructor(SIGNATURE);
                        return (Source)cns.newInstance(new Object[]{u});
                } catch (ClassNotFoundException e) {  //legal, not all sources exists internally  
                        return new SourceServer(u); //fetch from server.
                } catch (NoSuchMethodException e) {  //no useful constructor, encourage coder to do some..
                        throw new RuntimeException("Source: No valid public constructor at class "+cl);
                } catch (Exception e){ //security, class load, ... 
                        throw new RuntimeException(e);
                }
        }
        
        static String getParam(URL url, String param){
                String value=null;
                for(String part : url.getQuery().split("&")){
                        String[] tmp=part.split("=");
                        if (tmp[0].equals(param))
                                if (tmp.length>1)
                                        value=HTTPUtils.decode(tmp[1]);
                                else 
                                        value="";
                }
                return value;
        }       
        
        public Source(URL url) {
                super("Source");                
                setPriority(Thread.MIN_PRIORITY); //don't slow down animation

                this.url=url;
                this.keyword=getParam(url, "keyword");
                this.silent=!Prefs.current.verbose;
                
                graph=new Graph();
                        
                start();
        }
        
        public void run() {
                try {
                        buildGraph();
                        finished=true; //present the result to the fetchers listener
                } catch (Exception e) {
                        if (Prefs.current.verbose){
                                System.out.println(" failed: "+e);                              
                        }
                }               
        }
        
        abstract void buildGraph() throws IOException; 
        
        Node add(String text, String type, Node parent){
                int id=getId(text,type);                
                Node n= new Node(id, text,type);
                
                if (graph.findNode(id)==null)
                        graph.addNode(n);
                
                if (parent!=null){
                        Edge e=new Edge(n, parent, ""+edgecount++, "in");
                        graph.addEdge(e);
                }
                
                return n;
        }       
        
        int getId(String text, String type){
                return text.hashCode()^type.hashCode();
        }
        
}

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