YES SIR : Yet another Excel Sheet Simple Iterator Reader

ExcelSheetReader.groovy

import java.io.BufferedWriter
import java.io.File
import java.io.FileInputStream
import java.io.FileNotFoundException
import java.io.FileWriter
import java.io.FilenameFilter
import java.io.IOException
import java.util.ArrayList
import org.apache.poi.openxml4j.exceptions.InvalidFormatException
import org.apache.poi.ss.usermodel.Cell
import org.apache.poi.ss.usermodel.DataFormatter
import org.apache.poi.ss.usermodel.DateUtil
import org.apache.poi.ss.usermodel.FormulaEvaluator
import org.apache.poi.ss.usermodel.Row
import org.apache.poi.ss.usermodel.Sheet
import org.apache.poi.ss.usermodel.Workbook
import org.apache.poi.ss.usermodel.WorkbookFactory
/*
Maven
		<dependency>
			<groupId>org.apache.poi</groupId>
			<artifactId>poi</artifactId>
			<version>3.10.1</version>
		</dependency>
		<dependency>
			<groupId>org.apache.poi</groupId>
			<artifactId>poi-ooxml</artifactId>
			<version>3.10.1</version>
		</dependency>
		<dependency>
			<groupId>org.apache.poi</groupId>
			<artifactId>ooxml-schemas</artifactId>
			<version>1.1</version>
		</dependency>
*/
/*
@Grapes([
	@Grab(group='org.apache.poi', module='poi', version='3.10.1'),
	@Grab(group='org.apache.poi', module='poi-ooxml', version='3.10.1')
	@Grab(group='org.apache.poi', module='ooxml-schemas', version='1.1')
])
*/
class ExcelSheetReader implements Iterable {
	def file
	def sheetNum = 0
	int skipLines = 1
	int skipColumns = 0
    Iterator iterator(){
		def formatter,sheet,workbook,evaluator
		def lastRowNum = 0
      	def excel = file instanceof String ? new File(file) : file
        workbook = WorkbookFactory.create(excel)
        evaluator = workbook.getCreationHelper().createFormulaEvaluator()
        formatter = new DataFormatter(true)
        sheet = workbook.getSheetAt(sheetNum ?: 0)
    	lastRowNum = sheet.physicalNumberOfRows
       	int j = skipLines ?: 0
    	return [hasNext:{
		        	j < lastRowNum
	        	},
		        next:{
			        def record = []
	        		def row = sheet.getRow(j++)
			        int lastCellNum = row.lastCellNum
		        	if (lastCellNum >= 0) {
			            (0..(lastCellNum-1)).each{i->
			            	if (i>=skipColumns) {
	                        	record << getCellValueByType(row.getCell(i))
			            	}
			            }
		        	}
			        record

		        }
	    ] as Iterator
    }
	private getCellValueByType(cell,_cellType=null) {
		if (!cell) {
			return null
		}
		def cellType = _cellType ?: cell.cellType
		def result
		switch(cellType) {
			case Cell.CELL_TYPE_STRING:
				result = cell.richStringCellValue.string;
				break;
			case Cell.CELL_TYPE_NUMERIC:
				if (DateUtil.isCellDateFormatted(cell)) {
				  result = cell.dateCellValue
				} else {
				  result = cell.numericCellValue
				}
				break;
			case Cell.CELL_TYPE_BOOLEAN:
				result = cell.booleanCellValue
				break;
			case Cell.CELL_TYPE_FORMULA:
				result = showFormulas ? cell.cellFormula : getCellValueByType(cell, cell.cachedFormulaResultType)
				break
		}
		return result
	}
/*
    static main(args){
    	//Example Usage
    	new ExcelSheetReader(file:args[0],sheetNum:1,skipLines:2,skipColumns:4).eachWithIndex{row,i->
    		println "${++i} : ${row.join('\t')}"
    	}
    }
*/

}