readExcell

import org.apache.poi.hssf.usermodel.*;import org.apache.poi.poifs.filesystem.POIFSFileSystem;import org.apache.poi.ss.usermodel.*;import org.apache.poi.xssf.extractor.XSSFExcelExtractor;import org.apache.poi.xssf.usermodel.XSSFCell;import org.apache.poi.xssf.usermodel.XSSFSheet;import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import java.io.*;import java.util.Iterator;import java.util.List;
public class Main {
//////////////////////////////////////


Excel.Application xlApp = new Excel.Application();
Excel.Workbook xlWorkbook = xlApp.Workbooks.Open(@"sandbox_test.xlsx");
Excel._Worksheet xlWorksheet = xlWorkbook.Sheets[1];
Excel.Range xlRange = xlWorksheet.UsedRange;
int rowCount = xlRange.Rows.Count;
            int colCount = xlRange.Columns.Count;


////
// Theo Active (sheet đang được thao tác):
Worksheet excelWorksheet = (Worksheet)this.excelWorkbook.ActiveSheet;
Worksheet sheet = (Worksheet)xlApp.Worksheets[1];
sheet.Select(Type.Missing);
or

sheet.Activate();

//////////////

import org.apache.poi.ss.util.CellReference;
public class Excel {
    public static void convertInttoString(){
        CellReference cellReference = new CellReference(0,0);        System.out.println(cellReference.formatAsString());   
 String regex = "R([0-9]+)C([0-9]+)";
}

    public static void main(String[] args) {
        convertInttoString();    }
}


///////////

    private static final String FILE_NAME = "D:/test.xlsx";    static String handleStringCell(Cell cell) {
        String contents = cell.getRichStringCellValue().getString();        return contents;    }

    static String handleNonStringCell( Cell cell, DataFormatter formatter) {
        String contents = "";        CellType type = cell.getCellTypeEnum();        if (type == CellType.FORMULA) {
            type = cell.getCachedFormulaResultTypeEnum();        }

        if (type == CellType.NUMERIC) {
            CellStyle cs = cell.getCellStyle();
            if (cs != null && cs.getDataFormatString() != null) {
                contents = formatter.formatRawCellContents(
                        cell.getNumericCellValue(), cs.getDataFormat(), cs.getDataFormatString());            }
        }else{
            // No supported styling applies to this cell             contents = ((XSSFCell)cell).getRawValue();        }
       return contents;    }
    public static void main(String[] args) {
        //////////////////////////////////////////        DataFormatter dataFormatter = new DataFormatter();//////////////////////////////////////////
        try {

            FileInputStream excelFile = new FileInputStream(new File(FILE_NAME));            Workbook workbook = new XSSFWorkbook(excelFile);            Sheet datatypeSheet = workbook.getSheetAt(0);            Iterator<Row> iterator = datatypeSheet.iterator();
            while (iterator.hasNext()) {

                Row currentRow = iterator.next();                Iterator<Cell> cellIterator = currentRow.iterator();


                while (cellIterator.hasNext()) {

                    Cell currentCell = cellIterator.next();                    currentCell.getAddress();                  //  HSSFName name = (HSSFName) workbook.getNameAt(0);
//////////////////////////////////////////                    String cellStringValue = dataFormatter.formatCellValue(currentCell);                    System.out.println(cellStringValue);                    XSSFExcelExtractor a = new XSSFExcelExtractor((XSSFWorkbook) workbook);                    a.getText();
                    System.out.println("===================="+dataFormatter.formatCellValue(currentCell)+"============================");                    // Rows and cells
                    // Is it a formula one?                    if(currentCell.getCellTypeEnum() == CellType.FORMULA) {
                        if (currentCell.getCellFormula()!="") {
                            String contents = currentCell.getCellFormula();                            System.out.println(contents);                        } else {
                            if (currentCell.getCachedFormulaResultTypeEnum() == CellType.STRING) {
                                handleStringCell(currentCell);                            } else {
                                handleNonStringCell(currentCell, dataFormatter);                            }
                        }
                    } else if(currentCell.getCellTypeEnum() == CellType.STRING) {
                        handleStringCell( currentCell);                    } else {
                        handleNonStringCell(currentCell, dataFormatter);                    }

//////////////////////////////////////////
                }
                System.out.println();
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();        } catch (IOException e) {
            e.printStackTrace();        }

    }
}

//////////pom

<dependency>    <groupId>org.apache.poi</groupId>    <artifactId>poi-ooxml</artifactId>    <version>4.1.2</version></dependency>