csvparser.java

jboss规则引擎

package org.drools.decisiontable.parser.csv;

/*
 * Copyright 2005 JBoss Inc
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.List;

import org.drools.decisiontable.parser.DecisionTableParseException;
import org.drools.decisiontable.parser.DecisionTableParser;
import org.drools.decisiontable.parser.SheetListener;

/**
 * Csv implementation.
 * This implementation removes empty "cells" at the end of each line.
 * Different CSV tools may or may not put heaps of empty cells in.
 * 
 * Csv format is almost identical to XLS, with the one limitation:
 * Merged cells are not supported. To allow constraints to span across cells for the 
 * one column, this is achieved by using "..." at the end of a cell value.
 * If a cell value ends with "..." then it will be taken as spanned from the previous cell.
 * 
 * 
 * 
 * @author <a href="mailto:[e-mail]"> Michael Neale</a>
 */
public class CsvParser
    implements
    DecisionTableParser {

    private SheetListener _listener;
    private CsvLineParser _lineParser;

    public CsvParser(final SheetListener listener,
                     final CsvLineParser lineParser) {
        this._listener = listener;
        this._lineParser = lineParser;
    }

    public void parseFile(final InputStream inStream) {
        final BufferedReader reader = new BufferedReader( new InputStreamReader( inStream ) );
        try {
            this._listener.startSheet( "csv" );
            processRows( reader );
            this._listener.finishSheet();
        } catch ( final IOException e ) {
            throw new DecisionTableParseException( "An error occurred reading the CSV data.",
                                                   e );
        }
    }

    private void processRows(final BufferedReader reader) throws IOException {
        String line = reader.readLine();

        int row = 0;
        while ( line != null ) {

            final List cells = this._lineParser.parse( line );
            //remove the trailing empty "cells" which some tools smatter around
            //trimCells(cells);
            this._listener.newRow( row,
                              cells.size() );

            int startMergeCol = SheetListener.NON_MERGED;
            for ( int col = 0; col < cells.size(); col++ ) {
                String cell = (String) cells.get( col );

                startMergeCol = calcStartMerge( startMergeCol,
                                                col,
                                                cell );
                
                cell = calcCellText( startMergeCol,
                                     cell );
                
                this._listener.newCell( row,
                                   col,
                                   cell, startMergeCol );
            }
            row++;
            line = reader.readLine();
        }
        _listener.finishSheet();
    }

    String calcCellText(int startMergeCol,
                                String cell) {
        if (startMergeCol != SheetListener.NON_MERGED) {
            cell = cell.substring( 0, cell.length() - 3 );
        }
        return cell;
    }

    int calcStartMerge(int startMergeCol,
                               int col,
                               String cell) {
        if (cell.endsWith( "..." ) && startMergeCol == SheetListener.NON_MERGED) {
            startMergeCol = col;                    
        } else if (!cell.endsWith( "..." )) {
            startMergeCol = SheetListener.NON_MERGED;
        }
        return startMergeCol;
    }

    /** remove the trailing empty cells */
    private void trimCells(final List cells) {
        for ( int i = cells.size() - 1; i > 0; i-- ) {
            final String cell = (String) cells.get( i );
            if ( !cell.trim().equals( "" ) ) {
                return;
            } else {
                cells.remove( i );
            }
        }

    }

}