calendarfieldfunction.java

来自「EXCEL read and write」· Java 代码 · 共 92 行

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   this work for additional information regarding copyright ownership.
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package org.apache.poi.hssf.record.formula.functions;

import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;

import org.apache.poi.hssf.record.formula.eval.ErrorEval;
import org.apache.poi.hssf.record.formula.eval.Eval;
import org.apache.poi.hssf.record.formula.eval.EvaluationException;
import org.apache.poi.hssf.record.formula.eval.NumberEval;
import org.apache.poi.hssf.record.formula.eval.OperandResolver;
import org.apache.poi.hssf.record.formula.eval.ValueEval;
import org.apache.poi.hssf.usermodel.HSSFDateUtil;

/**
 * Implementation of Excel functions DAY, MONTH and YEAR
 * 
 * 
 * @author Guenter Kickinger [e-mail]
 */
public final class CalendarFieldFunction implements Function {
	
	public static final Function YEAR = new CalendarFieldFunction(Calendar.YEAR, false);
	public static final Function MONTH = new CalendarFieldFunction(Calendar.MONTH, true);
	public static final Function DAY = new CalendarFieldFunction(Calendar.DAY_OF_MONTH, false);
	
	private final int _dateFieldId;
	private final boolean _needsOneBaseAdjustment;

	private CalendarFieldFunction(int dateFieldId, boolean needsOneBaseAdjustment) {
		_dateFieldId = dateFieldId;
		_needsOneBaseAdjustment = needsOneBaseAdjustment;
	}

	public Eval evaluate(Eval[] operands, int srcCellRow, short srcCellCol) {
		if (operands.length != 1) {
			return ErrorEval.VALUE_INVALID;
		}

		int val;
		try {
			ValueEval ve = OperandResolver.getSingleValue(operands[0], srcCellRow, srcCellCol);
			val = OperandResolver.coerceValueToInt(ve);
		} catch (EvaluationException e) {
			return e.getErrorEval();
		}
		if (val < 0) {
			return ErrorEval.NUM_ERROR;
		}
		return new NumberEval(getCalField(val));
	}

	private int getCalField(int serialDay) {
		if (serialDay == 0) {
			// Special weird case
			// day zero should be 31-Dec-1899,  but Excel seems to think it is 0-Jan-1900
			switch (_dateFieldId) {
				case Calendar.YEAR: return 1900;
				case Calendar.MONTH: return 1;
				case Calendar.DAY_OF_MONTH: return 0;
			}
			throw new IllegalStateException("bad date field " + _dateFieldId);
		}
		Date d = HSSFDateUtil.getJavaDate(serialDay, false); // TODO fix 1900/1904 problem

		Calendar c = new GregorianCalendar();
		c.setTime(d);

		int result = c.get(_dateFieldId);
		if (_needsOneBaseAdjustment) {
			result++;
		}
		return result;
	}
}