lpfilewriter.java

著名IT公司ILog的APS高级排产优化引擎

package com.power.lpsolver.LPSolve;
import java.util.*;
import java.io.*;
import com.power.util.Message.*;

public class LPFileWriter
{
   private static final LPFileWriter INSTANCE =
                              new LPFileWriter();

    private BufferedWriter _myFileWriter; //initialized in subclass

   // Private constructor supresses
   // default public constructor
    private LPFileWriter( ) {
    }

    public static LPFileWriter getInstance( ) {
        return INSTANCE;
    }

    private StringBuffer content = new StringBuffer( );


    /**
     * Initializes a FileWriter for the report using global input directory and
     * local file name.
     */
	private void initFileWriter( String outDir ) {
		try {
            FileOutputStream w = new FileOutputStream( outDir );
            _myFileWriter = new BufferedWriter( new OutputStreamWriter( w ) );

		} catch (IOException e ) {
			System.out.println( e.getMessage() );
		}
	}

	public void write( String outDir ) {
        initFileWriter( outDir );
        MessageArea.getInstance().addMessage( "Creating MPS model ...\n" );
        MessageArea.getInstance().addMessage( "\tTotal number of constraints: " +
                Model.getInstance().getNumberOfRows() + "\n" );
        MessageArea.getInstance().addMessage( "\tTotal number of variables: " +
                Model.getInstance().getNumberOfColumns() + "\n" );

        printObj();

        Vector allCons = Model.getInstance().getModelConstraints().getConstraints();

		for( int i=0; i<allCons.size(); i++ ) {
			Constraint con = (Constraint) allCons.elementAt( i );
			printCon( con );

            if( (i%100) == 0 ) {
                MessageArea.getInstance().addMessage( "LP file writing: # of cons: "  + i + "\n" );
                flushFile();
                content = new StringBuffer();
            }
		}


        flushFile( );

        try{
            _myFileWriter.close();
        } catch( Exception e ) {
            MessageArea.getInstance().addMessage( "Error: " + e.getMessage() + "\n" );
        }

	}

    private boolean flushFile( ) {
        try{
            int i=0;
            for( ; i<(content.length()-1024); i+=1024 ) {
                _myFileWriter.write( content.toString(), i, 1024 );
                _myFileWriter.flush();
            }
            _myFileWriter.write( content.toString(), i, content.length() - i );
            _myFileWriter.flush();
            //_myFileWriter.close();
        } catch ( IOException e ) {
			System.out.println( "Error:" + e.getMessage() );
			return false;
        }
        return true;
    }

	public void printObj() {
		content.append( "Min" + ": " );
		Enumeration allElems = Model.getInstance().getObjectiveFunction().getElements().elements();
		ModelVariables mdlVars = Model.getInstance().getModelVariables();

		while( allElems.hasMoreElements() ) {
			Element elem = (Element) allElems.nextElement();
			Variable var = mdlVars.getVariable( elem.getColumnNumber() );
			if( elem.getCoefficient() > 0 ) {
				content.append( " + " );
			} else {
				content.append( " - " );
			}
			content.append( Math.abs( elem.getCoefficient() ) );
			content.append( var.getMPSName() );
		}

		content.append( ";\n" );
	}

    /**
     * Prints the constraint in a readable format (LP format).
     */
	public void printCon( Constraint con ) {
		//content += con.getName() + ": ";
		Enumeration allElems = con.getElements().elements();
		ModelVariables mdlVars = Model.getInstance().getModelVariables();

		while( allElems.hasMoreElements() ) {
			Element elem = (Element) allElems.nextElement();
			Variable var = mdlVars.getVariable( elem.getColumnNumber() );
			if( elem.getCoefficient() > 0 ) {
				content.append( " + " );
			} else {
				content.append( " - " );
			}
			content.append( Math.abs( elem.getCoefficient() ) );
			content.append( var.getMPSName() );
		}

		content.append( " " + con.getSign() + " " + con.getRHS() + ";\n" );
	}

}