请问大佬POI如何读取树形结构的excel文件?

import java.io.File;
import java.io.IOException;
import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
import org.apache.poi.ss.usermodel.Cell;
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;
import org.apache.poi.ss.util.CellRangeAddress;

public class POIImportDemo {
/**
* 读取excel数据
*
* @param path
*/
private void readExcelToObj(String path) {

    Workbook wb = null;
    try {
        wb = WorkbookFactory.create(new File(path));
        readExcel(wb, 0, 0, 0);
    } catch (InvalidFormatException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

/**
 * 读取excel文件
 * 
 * @param wb
 * @param sheetIndex    sheet页下标：从0开始
 * @param startReadLine 开始读取的行:从0开始
 * @param tailLine      去除最后读取的行
 */
private void readExcel(Workbook wb, int sheetIndex, int startReadLine, int tailLine) {
    Sheet sheet = wb.getSheetAt(sheetIndex);
    Row row = null;

    for (int i = startReadLine; i < sheet.getLastRowNum() - tailLine + 1; i++) {
        row = sheet.getRow(i);
        for (Cell c : row) {
            boolean isMerge = isMergedRegion(sheet, i, c.getColumnIndex());
            // 判断是否具有合并单元格
            if (isMerge) {
                String rs = getMergedRegionValue(sheet, row.getRowNum(), c.getColumnIndex());
                System.out.print(rs + "");
            } else {
                System.out.print(getCellValue(c) + "");
            }
        }
        System.out.println();

    }

}

/**
 * 获取合并单元格的值
 * 
 * @param sheet
 * @param row
 * @param column
 * @return
 */
public String getMergedRegionValue(Sheet sheet, int row, int column) {
    int sheetMergeCount = sheet.getNumMergedRegions();

    for (int i = 0; i < sheetMergeCount; i++) {
        CellRangeAddress ca = sheet.getMergedRegion(i);
        int firstColumn = ca.getFirstColumn();
        int lastColumn = ca.getLastColumn();
        int firstRow = ca.getFirstRow();
        int lastRow = ca.getLastRow();

        if (row >= firstRow && row <= lastRow) {

            if (column >= firstColumn && column <= lastColumn) {
                Row fRow = sheet.getRow(firstRow);
                Cell fCell = fRow.getCell(firstColumn);
                return getCellValue(fCell);
            }
        }
    }

    return null;
}

/**
 * 判断合并了行
 * 
 * @param sheet
 * @param row
 * @param column
 * @return
 */
private boolean isMergedRow(Sheet sheet, int row, int column) {
    int sheetMergeCount = sheet.getNumMergedRegions();
    for (int i = 0; i < sheetMergeCount; i++) {
        CellRangeAddress range = sheet.getMergedRegion(i);
        int firstColumn = range.getFirstColumn();
        int lastColumn = range.getLastColumn();
        int firstRow = range.getFirstRow();
        int lastRow = range.getLastRow();
        if (row == firstRow && row == lastRow) {
            if (column >= firstColumn && column <= lastColumn) {
                return true;
            }
        }
    }
    return false;
}

/**
 * 判断指定的单元格是否是合并单元格
 * 
 * @param sheet
 * @param row    行下标
 * @param column 列下标
 * @return
 */
private boolean isMergedRegion(Sheet sheet, int row, int column) {
    int sheetMergeCount = sheet.getNumMergedRegions();
    for (int i = 0; i < sheetMergeCount; i++) {
        CellRangeAddress range = sheet.getMergedRegion(i);
        int firstColumn = range.getFirstColumn();
        int lastColumn = range.getLastColumn();
        int firstRow = range.getFirstRow();
        int lastRow = range.getLastRow();
        if (row >= firstRow && row <= lastRow) {
            if (column >= firstColumn && column <= lastColumn) {
                return true;
            }
        }
    }
    return false;
}

/**
 * 判断sheet页中是否含有合并单元格
 * 
 * @param sheet
 * @return
 */
private boolean hasMerged(Sheet sheet) {
    return sheet.getNumMergedRegions() > 0 ? true : false;
}

/**
 * 合并单元格
 * 
 * @param sheet
 * @param firstRow 开始行
 * @param lastRow  结束行
 * @param firstCol 开始列
 * @param lastCol  结束列
 */
private void mergeRegion(Sheet sheet, int firstRow, int lastRow, int firstCol, int lastCol) {
    sheet.addMergedRegion(new CellRangeAddress(firstRow, lastRow, firstCol, lastCol));
}

/**
 * 获取单元格的值
 * 
 * @param cell
 * @return
 */
public String getCellValue(Cell cell) {

    if (cell == null)
        return "";

    if (cell.getCellType() == Cell.CELL_TYPE_STRING) {

        return cell.getStringCellValue();

    } else if (cell.getCellType() == Cell.CELL_TYPE_BOOLEAN) {

        return String.valueOf(cell.getBooleanCellValue());

    } else if (cell.getCellType() == Cell.CELL_TYPE_FORMULA) {

        return cell.getCellFormula();

    } else if (cell.getCellType() == Cell.CELL_TYPE_NUMERIC) {

        return String.valueOf(cell.getNumericCellValue());

    }
    return "";
}
}