poi读取树形excel

要读取树形结构的Excel，需要使用递归遍历的方式来读取每一个单元格。在读取Excel的过程中，需要判断当前单元格是否为合并单元格，如果是，则需要获取合并单元格的起始行、起始列、结束行和结束列，然后将当前单元格的值设置为合并单元格的起始单元格的值。

以下是一个示例代码，可以读取树形结构的Excel：

import org.apache.poi.ss.usermodel.*;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

public class ReadExcel {

    public static void main(String[] args) throws IOException {
        File file = new File("tree.xlsx");
        FileInputStream fis = new FileInputStream(file);

        Workbook workbook = WorkbookFactory.create(fis);
        Sheet sheet = workbook.getSheetAt(0);

        List<TreeNode> nodeList = new ArrayList<>();
        readTree(sheet, nodeList, 0, 0);

        for (TreeNode node : nodeList) {
            System.out.println(node);
        }
    }

    private static void readTree(Sheet sheet, List<TreeNode> nodeList, int row, int col) {
        Row currentRow = sheet.getRow(row);
        Cell currentCell = currentRow.getCell(col);

        if (currentCell == null || currentCell.getCellType() == CellType.BLANK) {
            return;
        }

        String value = currentCell.getStringCellValue();
        int level = getLevel(sheet, row, col);

        TreeNode node = new TreeNode(value, level);
        nodeList.add(node);

        int nextRow = row + 1;
        int nextCol = col + 1;

        while (nextRow <= sheet.getLastRowNum()) {
            Row childRow = sheet.getRow(nextRow);
            Cell childCell = childRow.getCell(col);

            if (childCell == null || childCell.getCellType() == CellType.BLANK) {
                nextRow++;
                continue;
            }

            int childLevel = getLevel(sheet, nextRow, col);

            if (childLevel <= level) {
                break;
            }

            String childValue = childCell.getStringCellValue();
            TreeNode childNode = new TreeNode(childValue, childLevel);
            node.addChild(childNode);

            readTree(sheet, nodeList, nextRow, nextCol);

            nextRow++;
        }

        if (currentCell.getCellType() == CellType.MERGE) {
            CellRangeAddress range = getMergedRegion(sheet, row, col);

            if (range != null) {
                int startRow = range.getFirstRow();
                int startCol = range.getFirstColumn();

                if (startRow != row || startCol != col) {
                    Cell startCell = sheet.getRow(startRow).getCell(startCol);
                    String startValue = startCell.getStringCellValue();
                    node.setValue(startValue);
                }
            }
        }
    }

    private static int getLevel(Sheet sheet, int row, int col) {
        Row currentRow = sheet.getRow(row);
        int level = 0;

        for (int i = 0; i < col; i++) {
            Cell cell = currentRow.getCell(i);

            if (cell != null && cell.getCellType() != CellType.BLANK) {
                level++;
            }
        }

        return level;
    }

    private static CellRangeAddress getMergedRegion(Sheet sheet, int row, int col) {
        int count = sheet.getNumMergedRegions();

        for (int i = 0; i < count; i++) {
            CellRangeAddress range = sheet.getMergedRegion(i);

            if (range.isInRange(row, col)) {
                return range;
            }
        }

        return null;
    }
}

class TreeNode {
    private String value;
    private int level;
    private List<TreeNode> children;

    public TreeNode(String value, int level) {
        this.value = value;
        this.level = level;
        this.children = new ArrayList<>();
    }

    public void addChild(TreeNode child) {
        this.children.add(child);
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();

        for (int i = 0; i < level; i++) {
            sb.append("  ");
        }

        sb.append(value);

        for (TreeNode child : children) {
            sb.append("\n").append(child);
        }

        return sb.toString();
    }
}

在上面的代码中，`readTree` 方法使用递归的方式遍历Excel表格，`getLevel` 方法获取单元格所在的层级，`getMergedRegion` 方法获取合并单元格的范围。`TreeNode` 类表示树形结构中的一个节点，包含节点的值、层级和子节点列表。