package com.power.util.urltools;import java.util.*;import java.io.*;import java.net.*;import com.power.pipeengine.Variable.*;import com.power.pipeengine.Constraint.*;import com.power.pipe.*;import com.power.pipeengine.*;import com.power.util.Message.*;import com.power.lpsolver.LPSolve.*;public class URLFileReader{    private static final URLFileReader INSTANCE =                              new URLFileReader();   // Private constructor supresses   // default public constructor    private URLFileReader( ) {    }    public static URLFileReader getInstance( ) {        return INSTANCE;    }    private HttpURLConnection urlconn = null;    private String urlAddr = null;    public BufferedReader getReaderForURL( String addr,                                           String cmd,                                           String fileName  )    throws Exception    {		urlAddr = addr;		URL url = new URL ( urlAddr + "?cmd=" + cmd + "&FileName=" +                            fileName );		BufferedReader d = null;		InputStream in = null;		try {			urlconn = (HttpURLConnection)(url.openConnection());			urlconn.setRequestMethod("GET");			in = urlconn.getInputStream();			d = new BufferedReader(new InputStreamReader(in) );		}		catch(Exception e) {			MessageArea.getInstance().addMessage( "Error openning URL: " +                            urlAddr + "for file: " + fileName + "\n" );			return null;		}        return d;    }	public void closeURLConnection() {        if( urlconn != null ) {            urlconn.disconnect();        }	}	protected void publishFileReadingMsg() {		MessageArea.getInstance().addMessage(                "Reading file: model.out\n" );	}}