poi+easypoi实现表头多层循环，多级动态表头、树形结构动态表头、纵向合并单元格、多个sheet导出

前言

我前面也写过几篇关于easypoi复杂表格导出的文章，什么一对多纵向合并、多级表头、动态表头、多个sheet等，这些我写那几篇文章之前做项目都遇到过，并且都实现出来了。

感兴趣的可以看看：
easypoi多级表头、多个sheet导出，动态导出列、动态更改表头

easypoi一对多，纵向合并单元格，并且根据内容自适应行高

我就以为大部分表格导出都难不倒我了，没想到我碰到的表格还是不够多。

多级表头中，不知道大家有没有碰到过这种表头，如下图：

三级下面有n个四级，一级二级下面分别只有一个二级和三级。亦或是这种：

我一开始寻思这种表头用easypoi的 ExcelExportEntity 实现挺简单的呀，后面我用代码写了才发现这结果完全不是我想的样子啊上面那两张图是想要的理想效果，实际上的结果是这样的：

和这样的：

我直接：

这种情况就是合并单元格只能作用于上一级，而不能跨级。比如对二级来说，四级是它子级的子级，但是它并不能因为子级（三级）有多个子级，所以子级（三级）合并了，它本身也会合并。 用easypoi来导出的话，关于这个问题，我现在没有找到解决方案。

还有一点就是我明明每列都设置了列宽，但是四级3、四级4的列宽没起作用，四级1、四级2设置的列宽倒是起作用了。

发现用 ExcelExportEntity 行不通后，有想过使用模板，但是我项目中实际用的表头比较复杂，我用模板完全不知道要怎么把表头遍历出来。。。项目里用的大概是这种形式的表头：

我不知道在模板里遍历每一项的时候，怎么再遍历每一项里面的list。就是遍历一级时，怎么再把每个一级下面的二级list给遍历出来。我看了easypoi的官方文档，发现有个 模板支持多层循环 的实现，但是偏偏就这一点，它文档上的图片没了。。。

然后我开始找其他解决办法，看过很多关于easypoi复杂表头的文章，都没有找到我这种形式的表格。直到我看某篇文章的评论区时，终于看到个有遇到和我一样问题的人了，并且贴出了参考方案，我按照这个方法，终于做出来我想要的表头了！！解决方案我就是参考的这篇文章：JAVA POI 实现EXCEL 动态表头、动态添加数据（导入导出）、 Tree结构的遍历

解决

一、表头效果

我按照上面那篇文章，终于得到我想要的表头了，效果如图：


设置的列宽也有作用。

再看看用easypoi ExcelExportEntity 导出来的：

我设置的列宽也不起作用。

二、填充数据

表头可以了，接下来就是填充内容数据了，效果如下：

这里就有个问题了，因为所在单位这一列有连续多行是相同内容，所以我想要合并相同内容。

1、纵向合并

于是我在原先的代码基础上，加了纵向合并功能，需要设置哪几列是遇到相同内容要合并的。

/**
 * 把数据写入到单元格
 * @param headerCellList 表头数据
 * @param datas           行内数据
 * @param sheet           工作表（excel分页）
 * @param mergeIndex      需要纵向合并的单元格列号
 * @throws Exception void
 */
private void writeSheetContent(List<ColEntity> headerCellList, List<T> datas, HSSFSheet sheet, int rowIndex,List<Integer> mergeIndex, boolean rowFlag) throws Exception {
    boolean isMerge = false;// 是否纵向合并单元格
    if (mergeIndex != null && !mergeIndex.isEmpty()) isMerge = true;
    HSSFRow row = null;
    List<ColEntity> listCol = new ArrayList<>();
    rowFlag = false;
    if (rowFlag) {//暂时没有用 后面扩展用
        for (int i = 0, index = rowIndex; i < datas.size(); i++, index++) {
            row = sheet.createRow(index);//创建行
            for (int j = 0; j < headerCellList.size(); j++) {
                createColl(row, j, headerCellList.get(j).getFieldName(), datas.get(i));
            }
        }
    } else {
        getColEntityList(headerCellList, listCol);
        Map<Integer,  Map<Integer, String>> mergeMaps = new HashMap<>();// 需要合并的列：key 列号，value为单元格内容
        Map<Integer, String> mergeMap = null;// 需要合并的行：key 行号 value 为单元格内容
        for (int i = 0, index = rowIndex; i < datas.size(); i++, index++) {
            row = sheet.createRow(index);//创建行
            for (int j = 0; j < listCol.size(); j++) {
                ColEntity c = listCol.get(j);
                //数据列
                HSSFCell col = createCol(row, c, datas.get(i));
                if (col.toString().length()>0){
                    // 需要合并 并且 当前单元格所在的列包含在要合并的列中
                    if (isMerge && mergeIndex.contains(c.getCol())){
                        if (mergeMaps.get(c.getCol()) != null){ // 如果要合并的列已经有了，则直接去拿该列的数据
                            mergeMap = mergeMaps.get(c.getCol());
                        }else {
                            mergeMap = new HashMap<>();
                        }
                        // 当前行号为key，当前单元格内容为value
                        mergeMap.put(index,col.toString()); // 将当前单元格的内容添加到当前行号中
                        mergeMaps.put(c.getCol(),mergeMap);
                    }
                }
            }
        }
        if (isMerge) mergedCells(mergeMaps,sheet);
    }
}

/**
 * 纵向合并单元格
 * @param mergeMaps 需要合并的列：key 要合并的列号，value为单元格内容
 * @param sheet
 */
private void mergedCells(Map<Integer,  Map<Integer, String>> mergeMaps,HSSFSheet sheet){
    for (Integer colNum : mergeMaps.keySet()) { // 遍历要合并的列，获取每一列的每一行
        Map<Integer, String> mergeMap = mergeMaps.get(colNum);// 当前这列每一行的内容：key为行号，value为单元格内容
        // 根据mergeMap的value，也就是单元格内容进行分组，每一组都是需要合并在一起的单元格（要合并的区域）
        Map<String, List<Map.Entry<Integer,String>>>result = mergeMap.entrySet().stream().collect(Collectors.groupingBy(c -> c.getValue()));
        System.out.println("\n合并的列号："+colNum);
        System.out.println("合并的区域："+result);
        for (String key : result.keySet()) {
            // list为这一组要合并的几个单元格
            List<Map.Entry<Integer, String>> list = result.get(key);
            int start = list.get(0).getKey(); // 开始合并的行号
            int end = list.get(list.size()-1).getKey(); // 结束合并的行号
            System.out.println("第"+colNum+"列开始合并的行号："+start+"\t第"+colNum+"列结束合并的行号："+"\t"+end+"。");
            if (start < end){ // 开始合并的行号必须小于结束合并的行号
                sheet.addMergedRegion(new CellRangeAddress(start, end, colNum,colNum));
            }
        }
    }
}

写好纵向合并的方法后，我们再来看看导出效果：（行号索引从0开始）

2、多个sheet

实现了纵向合并，项目中又根本不止一个sheet，所以我们还得实现导出多个sheet。

我在原先代码调用导出方法的基础上，再对这个方法传入的参数进行重新封装。原先是表头数据和内容数据都用的list，要实现多个sheet的话，我再用map把每个sheet的表头数据list、内容数据list给封装起来，用sheet名称为key。

/**
 * 返回workbook（单个sheet）
 * @param listTpamsColEntity 表头数据
 * @param datas           行内数据
 */
public HSSFWorkbook exportWorkbook(List<ColEntity> listTpamsColEntity, List<T> datas) throws Exception {
    splitDataToSheets(this.title,datas, listTpamsColEntity,null, false);
    ExcelStyleUtil.setStyleByType(this.workbook,null,0,null);
    return this.workbook;
}

/**
 * 返回workbook（多个sheet），这里全部sheet都用的同一个样式
 * @param titles          表头数据（key为sheet名称，value为表头数据）
 * @param datas           行内数据（key为sheet名称，value为行内数据）
 */
public HSSFWorkbook exportWorkbook(Map<String,List<ColEntity>> titles, Map<String,List<T>> datas) throws Exception {
    for (String sheetName : titles.keySet()) {
        List<ColEntity> colEntityList = titles.get(sheetName);
        List<T> tList = datas.get(sheetName);
        splitDataToSheets(sheetName,tList, colEntityList,null,false);
    }
    ExcelStyleUtil.setStyleByType(this.workbook,null,0,null);
    return this.workbook;
}

最后导出如图：

三、完整代码

<dependencies>
    
    <dependency>
        <groupId>javax.servletgroupId>
        <artifactId>servlet-apiartifactId>
        <version>2.5version>
    dependency>

    
    <dependency>
        <groupId>cn.afterturngroupId>
        <artifactId>easypoi-baseartifactId>
        <version>4.4.0version>
    dependency>
dependencies>

1、表头实体类

用于封装表头内容。可以将数据库查出来的动态表头数据用这个实体类封装起来，也可以直接用数据库表映射的实体类

/**
 * 表头的实体类： 在具体的项目里，可以是你从数据库里查询出来的数据
 */
public class TitleEntity {
    /**
     * id
     */
    public  String id;
    /**
     * 父级id
     */
    public  String pid;
    /**
     * 表头内容
     */
    public  String content;
    /**
     * 映射的字段名
     */
    public  String fieldName;
    /**
     * 列宽
     */
    public int width;

    private TitleEntity(){}

    public TitleEntity(String id, String pid, String content, String fieldName, int width) {
        this.id = id;
        this.pid = pid;
        this.content = content;
        this.fieldName = fieldName;
        this.width = width;
    }
    // ......省略getter、setter
}

2、单元格实体类

import java.util.ArrayList;
import java.util.List;

/**
 * 单元格
 */
public class ColEntity {
    /**
     * 单元格内容
     */
    private String content;
    /**
     * 字段名称，用户导出表格时反射调用
     */
    private String fieldName;
    /**
     * 这个单元格的集合
     */
    private List<ColEntity> cellList = new ArrayList<ColEntity>();
    /**
     * 总行数
     */
    private int totalRow;
    /**
     * 总列数
     */
    private int totalCol;
    /**
     * excel第几行
     */
    private int row;
    /**
     * excel第几列
     */
    private int col;
    /**
     * excel 跨多少行
     */
    private int rLen;
    /**
     * excel跨多少列
     */
    private int cLen;
    /**
     * 是否有子节点
     */
    private boolean hasChildren;
    /**
     * 树的级别 从0开始
     */
    private int treeStep;
    /**
     * 树的id
     */
    private String id;
    /**
     * 树的父级id
     */
    private String pid;
    /**
     * 列宽
     */
    private int width;
    
    // ......省略getter、setter
}

3、构建树形结构工具类

import com.entity.ColEntity;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

/**
 * excel poi 处理tree结构的数据 工具类
 */
public class ExcelTreeUtil {
    
    /**
     * 传入的id 必须存在list集合里
     * 获取某节点的深度
     * @param list
     * @param id   根节点
     * @param step 当前节点级别
     * @return
     */
    public static int getTreeStep(List<ColEntity> list, String id, int step) {
        if ("".equals(id) || null == id) return step;
        for (ColEntity cc : list) {
            if (id.equals(cc.getId())) {
                int temp = step + 1;
                return getTreeStep(list, cc.getPid(), temp);
            }
        }
        return step;
    }

    /**
     * 遍历所有数据 获取树最大的深度
     * @param list
     * @return
     */
    public static int getMaxStep(List<ColEntity> list) {
        List<Integer> nums = new ArrayList<>();
        for (ColEntity cc : list) {
            nums.add(getTreeStep(list, cc.getId(), 0));
        }
        return Collections.max(nums);
    }

    /**
     * 获取最底部子节点的个数 所有叶子节点个数
     * @param list
     * @param did
     * @return
     */
    public static int getDownChildren(List<ColEntity> list, String did) {
        int sum = 0;
        for (ColEntity cc : list) {
            if (did.equals(cc.getPid())) {
                sum++;
                //判断该节点 是否有子节点
                if (hasChild(list, cc)) {
                    sum += getDownChildren(list, cc.getId()) - 1;
                }
            }
        }
        return sum;
    }

    /**
     * 获取父节点
     * @param list 所有的list数据，一条一条
     * @param did  当前节点id
     * @return
     */
    public static ColEntity getParentCol(List<ColEntity> list, String did) {
        for (ColEntity cc : list) {
            if (did != null && did.equals(cc.getId())) {
                return cc;
            }
            if (did == null && did == cc.getId()) {
                return cc;
            }
        }
        return new ColEntity() {{
            setCol(0);
            setRow(0);
        }};
    }

    /**
     * 获取兄弟节点个数 这个必须是有排序的
     * @param list   所有的list数据，一条一条
     * @param ColEntity 当前节点信息
     * @return
     */
    public static int getBrotherChilNum(List<ColEntity> list, ColEntity ColEntity) {
        int sum = 0;
        for (ColEntity cc : list) {
            if (ColEntity.getId().equals(cc.getId())) {
                break;
            }
            if (!ColEntity.getPid().equals(cc.getPid())) {
                continue;
            }
            int temp = getDownChildren(list, cc.getId());
            if (temp == 0 || temp == 1) {
                sum++;
            } else {
                sum += temp;
            }
        }
        return sum;
    }

    /**
     * 根据某节点的第几层的父节点id
     * @param list 所有的list数据，一条一条
     * @param id   当前节点id
     * @param step 第几层(深度 从零开始)
     * @return
     */
    public static String getStepParentId(List<ColEntity> list, String id, int step) {
        String f_id = null;
        for (ColEntity cc : list) {
            if (id.equals(cc.getId())) {
                int cstep = getTreeStep(list, cc.getId(), 0);
                if (step == cstep) {
                    return id;
                }
                int fstep = getTreeStep(list, cc.getPid(), 0);
                if (step == fstep) {
                    f_id = cc.getPid();
                    break;
                } else {
                    getStepParentId(list, cc.getPid(), step);
                }
            }
        }
        return f_id;
    }

    /**
     * 判断是否有子节点
     * @param list 遍历的数据
     * @param node 某个节点
     * @return
     */
    public static boolean hasChild(List<ColEntity> list, ColEntity node) {
        return getChildList(list, node).size() > 0;
    }

    /**
     * 得到子节点列表
     * @param list 遍历的数据
     * @param node 某个节点
     * @return
     */
    public static List<ColEntity> getChildList(List<ColEntity> list, ColEntity node) {
        List<ColEntity> nodeList = new ArrayList<>();
        Iterator<ColEntity> it = list.iterator();
        while (it.hasNext()) {
            ColEntity n = (ColEntity) it.next();
            if (n.getPid() != null && n.getPid().equals(node.getId())) {
                nodeList.add(n);
            }
        }
        return nodeList;
    }

    /**
     * 使用递归方法建树
     * @param treeNodes
     */
    public static List<ColEntity> buildByRecursive(List<ColEntity> treeNodes, String rootID) {
        List<ColEntity> trees = new ArrayList<>();
        boolean flag = false;
        boolean sflag = false;
        for (ColEntity treeNode : treeNodes) {
            if ((rootID == null && rootID == treeNode.getId())) {
                flag = true;
            }
            if (rootID != null && rootID.equals(treeNode.getId())) {
                flag = true;
            }
            if (flag) {
                trees.add(findChildren(treeNode, treeNodes));
                flag = false;
            }
        }
        if (trees.size() <= 0) {
            for (ColEntity treeNode : treeNodes) {
                if ((rootID == null && rootID == treeNode.getPid())) {
                    sflag = true;
                }
                if (rootID != null && rootID.equals(treeNode.getPid())) {
                    sflag = true;
                }
                if (sflag) {
                    trees.add(findChildren(treeNode, treeNodes));
                    sflag = false;
                }
            }
        }
        return trees;
    }

    /**
     * 递归查找子节点
     * @param treeNodes
     * @return
     */
    public static ColEntity findChildren(ColEntity treeNode, List<ColEntity> treeNodes) {
        for (ColEntity it : treeNodes) {
            if (treeNode.getId().equals(it.getPid())) {
                if (treeNode.getCellList() == null) {
                    treeNode.setCellList(new ArrayList<>());
                }
                treeNode.getCellList().add(findChildren(it, treeNodes));
            }
        }
        return treeNode;
    }
}

4、excel导出样式工具类

import cn.afterturn.easypoi.excel.entity.params.ExcelExportEntity;
import cn.afterturn.easypoi.excel.entity.params.ExcelForEachParams;
import cn.afterturn.easypoi.excel.export.styler.IExcelExportStyler;
import org.apache.poi.ss.usermodel.*;

import java.util.List;

/**
 * excel导出样式设置工具类
 * 基础样式、自适应行高、隔行背景色
 */
public class ExcelStyleUtil implements IExcelExportStyler {
    private ExcelStyleUtil(){}

    private static final short STRING_FORMAT = (short) BuiltinFormats.getBuiltinFormat("TEXT");
    private static final short FONT_SIZE_TEN = 10;
    private static final short FONT_SIZE_ELEVEN = 11;
    private static final short FONT_SIZE_TWELVE = 12;
    private static final short height = 30;

    /**
     * 大标题样式
     */
    private CellStyle headerStyle;
    /**
     * 每列标题样式
     */
    private CellStyle titleStyle;
    /**
     * 数据行样式
     */
    private CellStyle styles;

    public ExcelStyleUtil(Workbook workbook) {
        this.init(workbook);
    }

    /**
     * 初始化样式
     * @param workbook
     */
    private void init(Workbook workbook) {
        this.headerStyle = initHeaderStyle(workbook);
        this.titleStyle = initTitleStyle(workbook,true,FONT_SIZE_ELEVEN);
        this.styles = initStyles(workbook);
    }

    @Override
    public CellStyle getHeaderStyle(short i) {
        return headerStyle;
    }

    @Override
    public CellStyle getTitleStyle(short i) {
        return titleStyle;
    }

    @Override
    public CellStyle getTemplateStyles(boolean b, ExcelForEachParams excelForEachParams) {
        return null;
    }

    @Override
    public CellStyle getStyles(boolean b, ExcelExportEntity excelExportEntity) {
        return styles;
    }

    @Override
    public CellStyle getStyles(Cell cell, int i, ExcelExportEntity entity, Object o, Object o1) {
        return getStyles(true, entity);
    }

    /**
     * 获取样式
     * @param style 1 大标题样式 2 表头样式 3 内容样式
     */
    public static CellStyle getStyles(Workbook workbook,int style) {
        CellStyle cellStyle = null;
        switch (style){
            case 1:
                cellStyle = initHeaderStyle(workbook);
                break;
            case 2:
                cellStyle = initTitleStyle(workbook,true,FONT_SIZE_ELEVEN);
                break;
            case 3:
                cellStyle = initStyles(workbook);
                break;
            default:
                cellStyle = initStyles(workbook);
                break;
        }
        cellStyle.setDataFormat(STRING_FORMAT);
        return cellStyle;
    }

    /**
     * 初始化--大标题样式
     */
    private static CellStyle initHeaderStyle(Workbook workbook) {
        CellStyle style = getBaseCellStyle(workbook);
        style.setFont(getFont(workbook, FONT_SIZE_TWELVE, true));
        return style;
    }

    /**
     * 初始化--每列标题样式
     */
    private static CellStyle initTitleStyle(Workbook workbook,boolean isBold,short size) {
        CellStyle style = getBaseCellStyle(workbook);
        style.setFont(getFont(workbook, size, isBold));
        //背景色
        style.setFillForegroundColor(IndexedColors.TAN.getIndex());
        style.setFillPattern(FillPatternType.SOLID_FOREGROUND);
        return style;
    }

    /**
     * 初始化--数据行样式
     */
    private static CellStyle initStyles(Workbook workbook) {
        CellStyle style = getBaseCellStyle(workbook);
        style.setFont(getFont(workbook, FONT_SIZE_TEN, false));
        style.setDataFormat(STRING_FORMAT);
        return style;
    }

    /**
     * 设置隔行背景色
     */
    public static CellStyle getRowBackground(Workbook workbook) {
        CellStyle style = getBaseCellStyle(workbook);
        style.setFont(getFont(workbook, FONT_SIZE_TEN,false));
        //背景色
        style.setFillForegroundColor(IndexedColors.LAVENDER.getIndex());
        style.setFillPattern(FillPatternType.SOLID_FOREGROUND);
        style.setDataFormat(STRING_FORMAT);
        return style;
    }

    /**
     * 基础样式
     */
    private static CellStyle getBaseCellStyle(Workbook workbook) {
        CellStyle style = workbook.createCellStyle();
        //下边框
        style.setBorderBottom(BorderStyle.THIN);
        //左边框
        style.setBorderLeft(BorderStyle.THIN);
        //上边框
        style.setBorderTop(BorderStyle.THIN);
        //右边框
        style.setBorderRight(BorderStyle.THIN);
        //水平居中
        style.setAlignment(HorizontalAlignment.CENTER);
        //上下居中
        style.setVerticalAlignment(VerticalAlignment.CENTER);
        //设置自动换行
        style.setWrapText(true);
        return style;
    }

    /**
     * 字体样式
     * @param size   字体大小
     * @param isBold 是否加粗
     */
    private static Font getFont(Workbook workbook, short size, boolean isBold) {
        Font font = workbook.createFont();
        //字体样式
        font.setFontName("宋体");
        //是否加粗
        font.setBold(isBold);
        //字体大小
        font.setFontHeightInPoints(size);
        return font;
    }

    /**
     * 根据type设置workbook
     * @param workbook
     * @param type 类型（0 默认 1 设置隔行背景 2 自适应行高 3 设置隔行背景同时自适应行高）
     * @param autoRowHeight 需要自适应行高的行号
     */
    public static void setStyleByType(Workbook workbook,String sheetName,int type,List<Integer> autoRowHeight){
        if (sheetName != null && sheetName.length()>0){
            Sheet sheet = workbook.getSheet(sheetName);
            setSheetStyleByType(workbook,sheet,type,autoRowHeight);
        }else {
            int sheetNum = workbook.getNumberOfSheets();
            for (int i = 0; i < sheetNum; i++) {
                Sheet sheet = workbook.getSheetAt(i);
                setSheetStyleByType(workbook,sheet,type,autoRowHeight);
            }
        }
    }

    public static void setSheetStyleByType(Workbook workbook,Sheet sheet,int type,List<Integer> autoRowHeight){
        if (type==1 || type == 3){ // 1和3，设置隔行背景
            setRowBackground(workbook,sheet);
        }
        int lastRowNum = sheet.getLastRowNum();
        for(int j = 0; j <= lastRowNum; j++) {
            Row row = sheet.getRow(j);
            row.setHeightInPoints(height); // 默认行高
            if (type==2 || type == 3){ // 2和3，设置自适应行高
                if (autoRowHeight != null && autoRowHeight.contains(j)){ // 不为空，则只有指定行号的行需要自适应行高
                    autoRowHeight(row);
                }else { // 为null，则表示全部行都需要自适应行高
                    autoRowHeight(row);
                }
            }
        }
    }

    /**
     * 偶数行设置背景色
     */
    public static void setRowBackground(Workbook workbook,Sheet sheet){
        CellStyle styles = getRowBackground(workbook);
        for(int i = 0; i <= sheet.getLastRowNum(); i ++) {
            if (i%2==0 && i>0){ // 标题用全局的标题样式，就不单独设置样式了，所以排除标题
                Row row = sheet.getRow(i);
                for(int j = 0; j < row.getPhysicalNumberOfCells(); j ++) {
                    Cell cell = row.getCell(j);
                    cell.setCellStyle(styles);
                }
            }
        }
    }

    /**
     * 设置自适应行高
     */
    public static void autoRowHeight(Row row){
        //根据内容长度设置行高
        int enterCnt = 0;
        for(int j = 0; j < row.getPhysicalNumberOfCells(); j ++) {
            Cell cell = row.getCell(j);
            if (cell != null){
                int rwsTemp = row.getCell(j).toString().length();
                //这里取每一行中的每一列字符长度最大的那一列的字符
                if (rwsTemp > enterCnt) {
                    enterCnt = rwsTemp;
                }
            }
        }
        row.setHeightInPoints(height); // 设置默认行高为35
        //如果字符长度大于35，根据内容来设置相应的行高
        if (enterCnt>height){
            long d = Math.round((double) enterCnt / (double) height)+2;
            row.setHeightInPoints(enterCnt*d);
        }
    }
}

5、excel poi导出处理工具类

import com.entity.ColEntity;
import org.apache.poi.hssf.usermodel.*;
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.ss.util.CellRangeAddress;
import org.apache.poi.ss.util.RegionUtil;

import java.io.File;
import java.io.FileOutputStream;
import java.lang.reflect.Field;
import java.text.SimpleDateFormat;
import java.util.*;
import java.util.stream.Collectors;

/**
 * excel poi 处理工具
 * 概念-> 表头数据:报表的表头
 * 行内数据:表头以下的数据
 * 功能:动态生成单级，多级Excel表头，多个sheet，纵向合并单元格
 * 备注：tree型结构数据的root节点的id默认为零（0）
 */
public class ExcelPoiUtil<T> {

    /**
     * excel 对象
     */
    private HSSFWorkbook workbook;
    /**
     * 表格标题
     */
    private String title;
    /**
     * 表头样式
     */
    private CellStyle styleHead;
    /**
     * 主体样式
     */
    private CellStyle styleBody;
    /**
     * 日期格式化,默认yyyy-MM-dd HH:mm:ss
     */
    private SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

    public HSSFWorkbook getWorkbook() {
        return workbook;
    }

    public void setWorkbook(HSSFWorkbook workbook) {
        this.workbook = workbook;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public CellStyle getStyleHead() {
        return styleHead;
    }

    public void setStyleHead(CellStyle styleHead) {
        this.styleHead = styleHead;
    }

    public CellStyle getStyleBody() {
        return styleBody;
    }

    public void setStyleBody(CellStyle styleBody) {
        this.styleBody = styleBody;
    }

    public SimpleDateFormat getSdf() {
        return sdf;
    }

    public void setSdf(SimpleDateFormat sdf) {
        this.sdf = sdf;
    }

    /**
     * 无参数 初始化 对象
     */
    public ExcelPoiUtil() {
        this.title = "sheet1";
        this.workbook = new HSSFWorkbook();
        init();
    }

    public ExcelPoiUtil(String title) {
        this.title = title;
        this.workbook = new HSSFWorkbook();
        init();
    }

    /**
     * 内部统一调用的样式初始化
     */
    private void init() {
        this.styleHead = ExcelStyleUtil.getStyles(workbook,2);
        this.styleBody = ExcelStyleUtil.getStyles(workbook,3);
    }

    /**
     * 返回workbook
     * @param listTpamsColEntity 表头数据
     * @param datas           行内数据
     */
    public HSSFWorkbook exportWorkbook(List<ColEntity> listTpamsColEntity, List<T> datas) throws Exception {
        splitDataToSheets(this.title,datas, listTpamsColEntity,null, false);
        ExcelStyleUtil.setStyleByType(this.workbook,null,0,null);
        return this.workbook;
    }

    /**
     * 返回workbook
     * @param listTpamsColEntity 表头数据
     * @param datas           行内数据
     * @param mergeIndex      需要纵向合并的单元格列号（默认有横向合并）
     */
    public HSSFWorkbook exportWorkbook(List<ColEntity> listTpamsColEntity, List<T> datas,List<Integer> mergeIndex) throws Exception {
        splitDataToSheets(this.title,datas, listTpamsColEntity, mergeIndex,false);
        ExcelStyleUtil.setStyleByType(this.workbook,null,0,null);
        return this.workbook;
    }

    /**
     * 返回workbook
     * @param listTpamsColEntity 表头数据
     * @param datas           行内数据
     * @param type            类型（0 默认 1 设置隔行背景 2 自适应行高 3 设置隔行背景同时自适应行高）
     * @param autoRowHeight   需要自适应行高的行号
     */
    public HSSFWorkbook exportWorkbook(List<ColEntity> listTpamsColEntity, List<T> datas,int type,List<Integer> autoRowHeight) throws Exception {
        splitDataToSheets(this.title,datas, listTpamsColEntity,null, false);
        ExcelStyleUtil.setStyleByType(this.workbook,null,type,autoRowHeight);
        return this.workbook;
    }

    /**
     * 返回workbook
     * @param listTpamsColEntity 表头数据
     * @param datas           行内数据
     * @param type            类型（0 默认 1 设置隔行背景 2 自适应行高 3 设置隔行背景同时自适应行高）
     * @param autoRowHeight   需要自适应行高的行号
     * @param mergeIndex      需要纵向合并的单元格列号（默认有横向合并）
     */
    public HSSFWorkbook exportWorkbook(List<ColEntity> listTpamsColEntity, List<T> datas,int type,List<Integer> autoRowHeight,List<Integer> mergeIndex) throws Exception {
        splitDataToSheets(this.title,datas, listTpamsColEntity,mergeIndex, false);
        ExcelStyleUtil.setStyleByType(this.workbook,null,type,autoRowHeight);
        return this.workbook;
    }

    /**
     * 返回workbook（多个sheet），这里全部sheet都用的同一个样式
     * @param titles          表头数据（key为sheet名称，value为表头数据）
     * @param datas           行内数据（key为sheet名称，value为行内数据）
     * @param type            样式类型，每个sheet都用这个（0 默认 1 设置隔行背景 2 自适应行高 3 设置隔行背景同时自适应行高）
     * @param autoRowHeight  需要自适应行高的行号，每个sheet都用这个
     * @param mergeIndex     需要纵向合并的单元格列号（默认有横向合并），每个sheet都用这个
     */
    public HSSFWorkbook exportWorkbook(Map<String,List<ColEntity>> titles, Map<String,List<T>> datas,int type,List<Integer> autoRowHeight,List<Integer> mergeIndex) throws Exception {
        for (String sheetName : titles.keySet()) {
            List<ColEntity> colEntityList = titles.get(sheetName);
            List<T> tList = datas.get(sheetName);
            splitDataToSheets(sheetName,tList, colEntityList,mergeIndex,false);
        }
        ExcelStyleUtil.setStyleByType(this.workbook,null,type,autoRowHeight);
        return this.workbook;
    }

    /**
     * 返回workbook（多个sheet），这里多个sheet都有不同样式
     * @param titles          表头数据（key为sheet名称，value为表头数据）
     * @param datas           行内数据（key为sheet名称，value为行内数据）
     * @param types           每个sheet的类型，key为sheet名称（0 默认 1 设置隔行背景 2 自适应行高 3 设置隔行背景同时自适应行高）
     * @param autoRowHeights  每个sheet需要自适应行高的行号
     * @param mergeIndexs     每个sheet需要纵向合并的单元格列号（默认有横向合并）
     */
    public HSSFWorkbook exportWorkbook(Map<String,List<ColEntity>> titles, Map<String,List<T>> datas,Map<String,Integer> types,
                                       Map<String,List<Integer>> autoRowHeights,Map<String,List<Integer>> mergeIndexs) throws Exception {
        for (String sheetName : titles.keySet()) {
            List<ColEntity> colEntityList = titles.get(sheetName);
            List<T> tList = datas.get(sheetName);
            int type = types == null ? 0 : types.get(sheetName) == null ? 0 : types.get(sheetName);
            List<Integer> autoRowHeight = autoRowHeights == null ? null : autoRowHeights.get(sheetName);
            List<Integer> mergeIndex = mergeIndexs == null ? null : mergeIndexs.get(sheetName);
            splitDataToSheets(sheetName,tList, colEntityList,mergeIndex,false);
            ExcelStyleUtil.setStyleByType(this.workbook,sheetName,type,autoRowHeight);
        }
        return this.workbook;
    }

    /**
     * 保存excel到本机指定的路径
     * @param workbook
     * @param filePath
     */
    public void save(HSSFWorkbook workbook, String filePath) {
        File file = new File(filePath);
        if (!file.getParentFile().exists()) {
            file.getParentFile().mkdirs();
        }
        FileOutputStream fOut = null;
        try {
            fOut = new FileOutputStream(file);
            workbook.write(fOut);
            fOut.flush();
        } catch (Exception e) {
            e.printStackTrace();
        }
        try {
            if (null != fOut) {
                fOut.close();
            }
        } catch (Exception e1) {
        }
    }

    /**
     * 导出Excel,适用于web导出excel
     * @param sheet           excel
     * @param data            行内数据
     * @param headerCellList 表头数据
     * @param mergeIndex      需要纵向合并的单元格列号（默认有横向合并）
     * @param rowFlag         输出展示数据的结构(表头下面行的数据)
     */
    private void writeSheet(HSSFSheet sheet, List<T> data, List<ColEntity> headerCellList,List<Integer> mergeIndex,boolean rowFlag) throws Exception {
        sheet = createHead(sheet, headerCellList.get(0).getTotalRow(), headerCellList.get(0).getTotalCol());
        createHead(headerCellList, sheet, 0);
        writeSheetContent(headerCellList, data, sheet, headerCellList.get(0).getTotalRow(),mergeIndex, rowFlag);
    }

    /**
     * 拆分sheet，因为每个sheet不能超过65535，否则会报异常
     * @param sheetName       sheet名称
     * @param data            行内数据
     * @param headerCellList 表头数据
     * @param mergeIndex      需要纵向合并的单元格列号（默认有横向合并）
     * @param rowFlag         输出展示数据的结构(表头下面行的数据)
     */
    private void splitDataToSheets(String sheetName,List<T> data, List<ColEntity> headerCellList,List<Integer> mergeIndex,boolean rowFlag) throws Exception {
        int dataCount = data.size();
        int maxColEntity = 65535;
        int pieces = dataCount / maxColEntity;
        for (int i = 1; i <= pieces; i++) {
            HSSFSheet sheet = this.workbook.createSheet(sheetName + i);
            List<T> subList = data.subList((i - 1) * maxColEntity, i * maxColEntity);
            writeSheet(sheet, subList, headerCellList,mergeIndex,rowFlag);
        }
        HSSFSheet sheet = this.workbook.createSheet(sheetName);
        writeSheet(sheet, data.subList(pieces * maxColEntity, dataCount), headerCellList,mergeIndex,rowFlag);
    }

    /**
     * 把数据写入到单元格
     * @param headerCellList 表头数据
     * @param datas           行内数据
     * @param sheet           工作表（excel分页）
     * @param mergeIndex      需要纵向合并的单元格列号（默认有横向合并）
     * @throws Exception void
     */
    private void writeSheetContent(List<ColEntity> headerCellList, List<T> datas, HSSFSheet sheet, int rowIndex,List<Integer> mergeIndex, boolean rowFlag) throws Exception {
        boolean isMerge = false;// 是否纵向合并单元格
        if (mergeIndex != null && !mergeIndex.isEmpty()) isMerge = true;
        HSSFRow row = null;
        List<ColEntity> listCol = new ArrayList<>();
        rowFlag = false;
        if (rowFlag) {//暂时没有用 后面扩展用
            for (int i = 0, index = rowIndex; i < datas.size(); i++, index++) {
                row = sheet.createRow(index);//创建行
                for (int j = 0; j < headerCellList.size(); j++) {
                    createColl(row, j, headerCellList.get(j).getFieldName(), datas.get(i));
                }
            }
        } else {
            getColEntityList(headerCellList, listCol);
            Map<Integer,  Map<Integer, String>> mergeMaps = new HashMap<>();// 需要合并的列：key 列号，value为单元格内容
            Map<Integer, String> mergeMap = null;// 需要合并的行：key 行号 value 为单元格内容
            for (int i = 0, index = rowIndex; i < datas.size(); i++, index++) {
                row = sheet.createRow(index);//创建行
                for (int j = 0; j < listCol.size(); j++) {
                    ColEntity c = listCol.get(j);
                    //数据列
                    HSSFCell col = createCol(row, c, datas.get(i));
                    if (col.toString().length()>0){
                        // 需要合并 并且 当前单元格所在的列包含在要合并的列中
                        if (isMerge && mergeIndex.contains(c.getCol())){
                            if (mergeMaps.get(c.getCol()) != null){ // 如果要合并的列已经有了，则直接去拿该列的数据
                                mergeMap = mergeMaps.get(c.getCol());
                            }else {
                                mergeMap = new HashMap<>();
                            }
                            // 当前行号为key，当前单元格内容为value
                            mergeMap.put(index,col.toString()); // 将当前单元格的内容添加到当前行号中
                            mergeMaps.put(c.getCol(),mergeMap);
                        }
                    }
                }
            }
            if (isMerge) mergedCells(mergeMaps,sheet);
        }
    }

    /**
     * 纵向合并单元格
     * @param mergeMaps 需要合并的列：key 要合并的列号，value为单元格内容
     * @param sheet
     */
    private void mergedCells(Map<Integer,  Map<Integer, String>> mergeMaps,HSSFSheet sheet){
        for (Integer colNum : mergeMaps.keySet()) { // 遍历要合并的列，获取每一列的每一行
            Map<Integer, String> mergeMap = mergeMaps.get(colNum);// 当前这列每一行的内容：key为行号，value为单元格内容
            // 根据mergeMap的value，也就是单元格内容进行分组，每一组都是需要合并在一起的单元格（要合并的区域）
            Map<String, List<Map.Entry<Integer,String>>>result = mergeMap.entrySet().stream().collect(Collectors.groupingBy(c -> c.getValue()));
            System.out.println("\n合并的列号："+colNum);
            System.out.println("合并的区域："+result);
            for (String key : result.keySet()) {
                // list为这一组要合并的几个单元格
                List<Map.Entry<Integer, String>> list = result.get(key);
                int start = list.get(0).getKey(); // 开始合并的行号
                int end = list.get(list.size()-1).getKey(); // 结束合并的行号
                System.out.println("第"+colNum+"列开始合并的行号："+start+"\t第"+colNum+"列结束合并的行号："+"\t"+end+"。");
                if (start < end){ // 开始合并的行号必须小于结束合并的行号
                    sheet.addMergedRegion(new CellRangeAddress(start, end, colNum,colNum));
                }
            }
        }
    }

    /**
     * 根据list 来创建单元格 暂时没有用
     * @param row
     * @param j
     * @param finame
     * @param t
     */
    private void createColl(HSSFRow row, int j, String finame, T t) {
        HSSFCell cell = row.createCell(j);  //创建单元格
        cell.setCellStyle(this.styleBody); //设置单元格样式
        String text = "";
        if (t instanceof List) {
            List<Map> temp = (List<Map>) t;
            if (j >= temp.size()) {
                return;
            }
            text = String.valueOf(temp.get(j).get(finame) == null ? "" : temp.get(j).get(finame));
        }
        HSSFRichTextString richString = new HSSFRichTextString(text);
        cell.setCellValue(richString);
    }

    /**
     * 把ColEntity的ColEntityList整理成一个list 过滤表头的脏数据
     * @param list    表头数据
     * @param listCol 返回新的list
     */
    private void getColEntityList(List<ColEntity> list, List<ColEntity> listCol) {
        for (ColEntity ColEntity : list) {
            if (ColEntity.getFieldName() != null) {
                listCol.add(ColEntity);
            }
            List<ColEntity> listChildren = ColEntity.getCellList();
            if (listChildren.size() > 0) {
                getColEntityList(listChildren, listCol);
            }
        }
    }

    /**
     * 创建行
     * @param row         Excel对应的行
     * @param tpamsColEntity 当前单元格属性
     * @param v
     * @param j
     * @return
     * @throws Exception
     */
    public int createRowVal(HSSFRow row, ColEntity tpamsColEntity, T v, int j) throws Exception {
        //遍历标题
        if (tpamsColEntity.getCellList() != null && tpamsColEntity.getCellList().size() > 0) {
            for (int i = 0; i < tpamsColEntity.getCellList().size(); i++) {
                createRowVal(row, tpamsColEntity.getCellList().get(i), v, j);
            }
        } else {
            createCol(row, tpamsColEntity, v);
        }
        return j;
    }

    /**
     * 创建单元格
     * @param row         Excel对应的行
     * @param colEntity 当前单元格对象
     * @param v
     * @throws Exception
     */
    public HSSFCell createCol(HSSFRow row, ColEntity colEntity, T v) throws Exception {
        HSSFCell cell = row.createCell(colEntity.getCol());  //创建单元格
        cell.setCellStyle(this.styleBody); //设置单元格样式
        final Object[] value = {null};
        if (v instanceof Map) {
            Map m = (Map) v;
            m.forEach((k, val) -> {
                if (k.equals(colEntity.getFieldName()) && !colEntity.isHasChildren()) {
                    value[0] = val;
                }
            });
        } else {
            Class<?> cls = v.getClass();// 拿到该类
            Field[] fields = cls.getDeclaredFields();// 获取实体类的所有属性，返回Field数组
            for (int i = 0; i < fields.length; i++) {
                Field f = fields[i];
                f.setAccessible(true); // 设置些属性是可以访问的
                if (colEntity.getFieldName().equals(f.getName()) && !colEntity.isHasChildren()){
                    value[0] = f.get(v);
                }
                if (value[0] instanceof Date) {
                    value[0] = parseDate((Date) value[0]);
                }
            }
        }
        if (value[0] != null) {
            HSSFRichTextString richString = new HSSFRichTextString(value[0].toString());
            cell.setCellValue(richString);
        }
        return cell;
    }

    /**
     * 时间转换
     * @param date
     * @return String
     */
    private String parseDate(Date date) {
        String dateStr = "";
        try {
            dateStr = this.sdf.format(date);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return dateStr;
    }


    /**
     * 根据数据的行数和列数，在excel创建单元格cell
     * @param sheetCo excel分页
     * @param r       excel 行数
     * @param c       excel 列数
     * @return
     */
    public HSSFSheet createHead(HSSFSheet sheetCo, int r, int c) {
        for (int i = 0; i < r; i++) {
            HSSFRow row = sheetCo.createRow(i);
            for (int j = 0; j < c; j++) {
                HSSFCell cell = row.createCell(j);
            }
        }
        return sheetCo;
    }

    /**
     * 使用递归 在excel写入表头数据 支持单级，多级表头的创建
     * @param cellList 表头数据
     * @param sheetCo  哪个分页
     * @param rowIndex 当前Excel的第几行
     */
    public void createHead(List<ColEntity> cellList, HSSFSheet sheetCo, int rowIndex) {
        HSSFRow row = sheetCo.getRow(rowIndex);
        int len = cellList.size();//当前行 有多少列
        for (int i = 0; i < len; i++) {//i是headers的索引，n是Excel的索引 多级表头
            ColEntity colEntity = cellList.get(i);
            //创建这一行的第几列单元格
            int r = colEntity.getRow();
            int rLen = colEntity.getRLen();
            int c = colEntity.getCol();
            int cLen = colEntity.getCLen();
            int endR = r + rLen;
            //解决表头导出时多一行问题
            if(endR > r){
                endR--;
            }
            int endC = c + cLen;
            if (endC > c) {
                endC--;
            }
            HSSFCell cell = row.getCell(c);
            HSSFRichTextString text = new HSSFRichTextString(colEntity.getContent());
            cell.setCellStyle(this.styleHead); //设置表头样式
            cell.setCellValue(text);
            // 合并单元格
            CellRangeAddress cra = new CellRangeAddress(r, endR, c, endC);
            //todo debug
            if (cra.getNumberOfCells() > 1) {
                sheetCo.addMergedRegion(cra);
            }
            sheetCo.setColumnWidth(c,colEntity.getWidth()*256);// 设置列宽
            // 使用RegionUtil类为合并后的单元格添加边框
            RegionUtil.setBorderBottom(BorderStyle.THIN, cra, sheetCo); // 下边框
            RegionUtil.setBorderLeft(BorderStyle.THIN, cra, sheetCo); // 左边框
            RegionUtil.setBorderRight(BorderStyle.THIN, cra, sheetCo); // 有边框
            if (colEntity.isHasChildren()) {
                rowIndex = r + 1;
                createHead(colEntity.getCellList(), sheetCo, rowIndex);
            }
        }
    }

    /**
     * 转换成ColEntity对象
     * 支持List的数据结构:map String ，只能是单级的数据
     * @param list 需要转换的数据
     */
    public List<ColEntity> colEntityTransformer(List<T> list) {
        List<ColEntity> lc = new ArrayList<>();
        if (list.get(0) instanceof Map) {
            final int[] i = {1};
            for (Map<String, String> m : (List<Map<String, String>>) list) {
                m.forEach((k, val) -> {
                    ColEntity tpamsColEntity = new ColEntity();
                    tpamsColEntity.setId(String.valueOf(i[0]));
                    tpamsColEntity.setPid("0");
                    tpamsColEntity.setContent(k);
                    tpamsColEntity.setFieldName(val);
                    tpamsColEntity.setWidth(20);
                    lc.add(tpamsColEntity);
                    i[0]++;
                });
            }
        } else {
            int i = 1;
            for (String s : (List<String>) list) {
                ColEntity tpamsColEntity = new ColEntity();
                tpamsColEntity.setId(String.valueOf(i));
                tpamsColEntity.setPid("0");
                tpamsColEntity.setContent(s);
                tpamsColEntity.setFieldName(null);
                tpamsColEntity.setWidth(20);
                lc.add(tpamsColEntity);
                i++;
            }
        }
        setParm(lc, "0");//处理一下
        List<ColEntity> s = ExcelTreeUtil.buildByRecursive(lc, "0");
        setColNum(lc, s);
        return s;
    }

    /**
     * 转换成ColEntity对象 返回tree数据结构
     * 支持：List
    public List<ColEntity> colEntityTransformer(List<T> list, Map<String,String> parm,String rootid) throws Exception {
        List<ColEntity> lc = new ArrayList<>();
        if (list.get(0) instanceof Map) {
            for (Map m : (List<Map>) list) {
                ColEntity colEntity = new ColEntity();
                m.forEach((k, val) -> {
                    if (parm.get("id").equals(k)) {
                        colEntity.setId(String.valueOf(val));
                    }
                    if (parm.get("pid").equals(k)) {
                        colEntity.setPid((String) val);
                    }
                    if (parm.get("content").equals(k)) {
                        colEntity.setContent((String) val);
                    }
                    if (parm.get("fieldName") != null && parm.get("fieldName").equals(k)) {
                        colEntity.setFieldName((String) val);
                    }
                    if (parm.get("width") != null && parm.get("width").equals(k)) {
                        colEntity.setWidth(Integer.parseInt(val.toString()));
                    }
                });
                lc.add(colEntity);
            }
        } else {
            for (T t : list) { // 反射
                ColEntity colEntity = new ColEntity();
                Class cls = t.getClass();
                Field[] fs = cls.getDeclaredFields();
                for (int i = 0; i < fs.length; i++) {
                    Field f = fs[i];
                    f.setAccessible(true); // 设置些属性是可以访问的
                    if (parm.get("id").equals(f.getName()) && f.get(t) != null) {
                        colEntity.setId(f.get(t).toString());
                    }
                    if (parm.get("pid").equals(f.getName()) && f.get(t) != null) {
                        colEntity.setPid(f.get(t).toString());
                    }
                    if (parm.get("content").equals(f.getName()) && f.get(t) != null) {
                        colEntity.setContent(f.get(t).toString());
                    }
                    if (f.get(t) != null && parm.get("fieldName") != null && parm.get("fieldName").equals(f.getName())) {
                        colEntity.setFieldName(f.get(t).toString());
                    }
                    if (parm.get("width").equals(f.getName()) && f.get(t) != null) {
                        colEntity.setWidth(Integer.parseInt(f.get(t).toString()));
                    }
                }
                lc.add(colEntity);
            }
        }
        setParm(lc, rootid); // 处理基础参数
        List<ColEntity> s = ExcelTreeUtil.buildByRecursive(lc, rootid); // 构建树结构
        setColNum(lc, s);
        return s;
    }

    /**
     * 设置基础的参数
     * @param list
     */
    public static void setParm(List<ColEntity> list, String rootid) {
        int row = 0; //excel第几行
        int rLen = 0; //excel 跨多少行
        int totalRow = ExcelTreeUtil.getMaxStep(list);
        int totalCol = ExcelTreeUtil.getDownChildren(list, rootid);
        for (int i = 0; i < list.size(); i++) {
            ColEntity poit = list.get(i);
            int tree_step = ExcelTreeUtil.getTreeStep(list, poit.getPid(), 0);//往上遍历tree
            poit.setTreeStep(tree_step);
            poit.setRow(tree_step);//设置第几行
            //判断是否有节点
            boolean hasCh = ExcelTreeUtil.hasChild(list, poit);
            poit.setHasChildren(hasCh);
            if (hasCh) {
                poit.setRLen(0);//设置跨多少行
            } else {
                if (tree_step < totalRow) {
                    rLen = totalRow - tree_step;
                }
                poit.setRLen(rLen);
            }
            poit.setTotalRow(totalRow);
            poit.setTotalCol(totalCol);
        }
    }

    /**
     * 设置基础的参数
     * @param list     所有list数据，一条一条
     * @param treeList 转成tree结构的list
     */
    public static void setColNum(List<ColEntity> list, List<ColEntity> treeList) {
        //int col = pcIndex;//excel第几列
        //int cLen ;//xcel跨多少列
        List<ColEntity> new_list = new ArrayList<>();//新的遍历list
        for (int i = 0; i < treeList.size(); i++) {
            ColEntity poit = treeList.get(i);
            //String temp_id = ExcelTreeUtil.getStepParentId(list,poit.getId() ,1);
            int col = ExcelTreeUtil.getParentCol(list, poit.getPid()).getCol();
            int brotherCol = ExcelTreeUtil.getBrotherChilNum(list, poit);
            poit.setCol(col + brotherCol);
            int cLen = ExcelTreeUtil.getDownChildren(list, poit.getId());
            if (cLen <= 1) {
                cLen = 0;
            }
            //else  cLen--;
            poit.setCLen(cLen);//设置跨多少列
            if (poit.getCellList().size() > 0) {
                new_list.addAll(poit.getCellList());
            }
        }
        if (new_list.size() > 0) {
            setColNum(list, new_list);
        }
    }
}

6、测试

import com.entity.ColEntity;
import com.entity.TitleEntity;
import com.google.common.collect.ImmutableMap;
import com.util.ExcelPoiUtil;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;

import java.util.*;

/**
 * 测试
 */
public class TestMain {

    static Map<String,List<ColEntity>> heads = new HashMap<>();// 最终导出的多个sheet的表头
    static Map<String,List<Map<String, String>>> datas = new HashMap<>();// 最终导出的多个sheet的内容
    static Map<String,Integer> types = new HashMap<>();// 最终导出的每个sheet的样式类型
    static Map<String,List<Integer>> autoRowHeights = new HashMap<>();// 最终导出的每个sheet的需要自适应行高的行号
    static Map<String,List<Integer>> mergeIndexs = new HashMap<>();// 最终导出的每个sheet的需要纵向合并的单元格列号

    public static void main(String[] args) throws Exception {
        单级表头();
        多级表头Map();
        多级表头Obj();
        多级表头Obj1();
        多级表头Obj2();
        纵向合并单元格();
        // 多个sheet导出
        ExcelPoiUtil excelTool = new ExcelPoiUtil();
        //HSSFWorkbook workbook = excelTool.exportWorkbook(heads, datas, 0, null, null); // 这里多个sheet都用的同一个样式
        HSSFWorkbook workbook = excelTool.exportWorkbook(heads, datas, types, null, mergeIndexs);
        excelTool.save(workbook,"C:\\Users\\Administrator\\Desktop\\多个sheet.xlsx");
    }

    public static void 单级表头() throws Exception {
        //单级的表头==============================================================
        Map<String, String> map = new HashMap<String, String>();
        map.put("登录名", "u_login_id");
        Map<String, String> map1 = new HashMap<String, String>();
        map1.put("用户名", "u_name");
        Map<String, String> map2 = new HashMap<String, String>();
        map2.put("角色", "u_role");
        Map<String, String> map3 = new HashMap<String, String>();
        map3.put("部门", "u_dep");
        Map<String, String> map4 = new HashMap<String, String>();
        map4.put("用户类型", "u_type");
        List<Map<String, String>> titleList = new ArrayList<>();
        titleList.add(map);
        titleList.add(map1);
        titleList.add(map2);
        titleList.add(map3);
        titleList.add(map4);
        //单级的 行内数据
        List<Map<String, String>> rowList = new ArrayList<>();
        for (int i = 0; i < 7; i++) {
            Map<String, String> m = new HashMap<String, String>();
            m.put("u_login_id", "登录名" + i);
            m.put("u_name", "张三" + i);
            m.put("u_role", "角色" + i);
            m.put("u_dep", "部门" + i);
            m.put("u_type", "用户类型" + i);
            rowList.add(m);
        }
        ExcelPoiUtil excelTool = new ExcelPoiUtil("单级表头的表格");
        List<ColEntity> titleData = excelTool.colEntityTransformer(titleList);
        HSSFWorkbook workbook = excelTool.exportWorkbook(titleData, rowList,1,null);
        excelTool.save(workbook,"C:\\Users\\Administrator\\Desktop\\单级表头.xlsx");
    }

    public static void 多级表头Map() throws Exception {
        List<Map<String,String>> titleList=new ArrayList<>();
        Map<String,String> titleMap=new HashMap<String,String>();
        titleMap.put("id","11");titleMap.put("pid","0");titleMap.put("content","登录名");titleMap.put("fieldName","u_login_id");titleMap.put("width","20");
        Map<String,String> titleMap1=new HashMap<String,String>();
        titleMap1.put("id","1");titleMap1.put("pid","0");titleMap1.put("content","姓名");titleMap1.put("fieldName","u_name");titleMap1.put("width","20");
        Map<String,String> titleMap2=new HashMap<String,String>();
        titleMap2.put("id","2");titleMap2.put("pid","0");titleMap2.put("content","角色加部门");titleMap2.put("fieldName",null);titleMap2.put("width","20");
        Map<String,String> titleMap3=new HashMap<String,String>();
        titleMap3.put("id","3");titleMap3.put("pid","2");titleMap3.put("content","角色");titleMap3.put("fieldName","u_role");titleMap3.put("width","15");
        Map<String,String> titleMap4=new HashMap<String,String>();
        titleMap4.put("id","4");titleMap4.put("pid","2");titleMap4.put("content","部门");titleMap4.put("fieldName","u_dep");titleMap4.put("width","15");
        Map<String,String> titleMap5=new HashMap<String,String>();
        titleMap5.put("id","22");titleMap5.put("pid","0");titleMap5.put("content","角色加部门1");titleMap5.put("fieldName",null);titleMap5.put("width","20");
        Map<String,String> titleMap6=new HashMap<String,String>();
        titleMap6.put("id","22_1");titleMap6.put("pid","22");titleMap6.put("content","角色1");titleMap6.put("fieldName","u_role");titleMap6.put("width","10");
        Map<String,String> titleMap7=new HashMap<String,String>();
        titleMap7.put("id","22_2");titleMap7.put("pid","22");titleMap7.put("content","部门1");titleMap7.put("fieldName","u_dep");titleMap7.put("width","10");
        titleList.add(titleMap); titleList.add(titleMap1); titleList.add(titleMap2); titleList.add(titleMap3); titleList.add(titleMap4);
        titleList.add(titleMap5); titleList.add(titleMap6); titleList.add(titleMap7);
        // 单级的 行内数据
        List<Map<String, String>> rowList = new ArrayList<>();
        for (int i = 0; i < 7; i++) {
            Map<String, String> m = new HashMap<String, String>();
            m.put("u_login_id", "登录名zx" + i);
            m.put("u_name", "张三" + i);
            m.put("u_role", "角色" + i);
            m.put("u_dep", "部门" + i);
            m.put("u_type", "用户类型" + i);
            rowList.add(m);
        }
        ExcelPoiUtil excelTool = new ExcelPoiUtil("List);
        Map<String,String> param = ImmutableMap.<String, String>builder().put("id", "id").put("pid", "pid")
                .put("content", "content").put("fieldName", "fieldName").put("width", "width").build();
        List<ColEntity> titleData = excelTool.colEntityTransformer(titleList,param, "0");
        //HSSFWorkbook workbook = excelTool.exportWorkbook(titleData, rowList);
        //excelTool.save(workbook,"C:\\Users\\Administrator\\Desktop\\多级表头Map.xlsx");
        heads.put("List,titleData);// 每个sheet的表头，sheet名称为key
        datas.put("List,rowList);// 每个sheet的内容，sheet名称为key
        types.put("List,0);// 每个sheet的样式类型，sheet名称为key
    }

    public static void 多级表头Obj() throws Exception {
        List<TitleEntity> titleList = new ArrayList<>();
        titleList.add(new TitleEntity("0", null, "总表", null,20));
        titleList.add(new TitleEntity("11", "0", "登录名2", "u_login_id",15));
        titleList.add(new TitleEntity("1", "0", "姓名", "u_name",15));
        titleList.add(new TitleEntity("2", "0", "角色加部门", null,20));
        titleList.add(new TitleEntity("3", "2", "角色", "u_role",20));
        titleList.add(new TitleEntity("4", "2", "部门", "u_dep",20));
        titleList.add(new TitleEntity("33", "0", "角色加部门1", null,15));
        titleList.add(new TitleEntity("33_1", "33", "角色33", "u_role",15));
        titleList.add(new TitleEntity("33_2", "33_1", "部门33", "u_dep",15));
        titleList.add(new TitleEntity("44", "0", "角色加部门2", null,10));
        titleList.add(new TitleEntity("44_1", "44", "角色44", "u_role",10));
        titleList.add(new TitleEntity("44_2", "44", "部门44", "u_dep",10));
        titleList.add(new TitleEntity("1_1", "1", "姓名1", "u_name",15));
        titleList.add(new TitleEntity("44_3", "44_2", "44_2", "u_dep",10));
        //单级的 行内数据
        List<Map<String, String>> rowList = new ArrayList<>();
        for (int i = 0; i < 7; i++) {
            Map<String, String> m = new HashMap<String, String>();
            m.put("u_login_id", "登录名" + i);
            m.put("u_name", "张三" + i);
            m.put("u_role", "角色" + i);
            m.put("u_dep", "部门" + i);
            m.put("u_type", "用户类型" + i);
            rowList.add(m);
        }
        ExcelPoiUtil excelTool = new ExcelPoiUtil("实体类（entity）多级表头表格");
        Map<String,String> param = ImmutableMap.<String, String>builder().put("id", "id").put("pid", "pid")
                .put("content", "content").put("fieldName", "fieldName").put("width", "width").build();
        List<ColEntity> titleData = excelTool.colEntityTransformer(titleList, param, "0");
        //HSSFWorkbook workbook = excelTool.exportWorkbook(titleData, rowList);
        //excelTool.save(workbook,"C:\\Users\\Administrator\\Desktop\\多级表头Obj.xlsx");
        heads.put("实体类（entity）多级表头表格",titleData);// 每个sheet的表头，sheet名称为key
        datas.put("实体类（entity）多级表头表格",rowList);// 每个sheet的内容，sheet名称为key
        types.put("实体类（entity）多级表头表格",0);// 每个sheet的样式类型，sheet名称为key
    }

    public static void 多级表头Obj1() throws Exception {
        List<TitleEntity> titleList = new ArrayList<>();
        titleList.add(new TitleEntity("title", null, "这里是title", null,20));
        titleList.add(new TitleEntity("一级1", "title", "一级1", null,20));
        titleList.add(new TitleEntity("一级2", "title", "一级2", null,20));
        titleList.add(new TitleEntity("二级1", "一级1", "二级1", null,20));
        titleList.add(new TitleEntity("二级2", "一级2", "二级2", null,20));
        titleList.add(new TitleEntity("三级1", "二级1", "三级1", null,20));
        titleList.add(new TitleEntity("三级2", "二级2", "三级2", null,20));
        titleList.add(new TitleEntity("四级1", "三级1", "四级1", "fieldName1",20));
        titleList.add(new TitleEntity("四级2", "三级1", "四级2", "fieldName2",20));
        titleList.add(new TitleEntity("四级3", "三级2", "四级3", "fieldName3",20));
        titleList.add(new TitleEntity("四级4", "三级2", "四级4", "fieldName4",20));
        //单级的 行内数据
        List<Map<String, String>> rowList = new ArrayList<>();
        for (int i = 0; i < 5; i++) {
            Map<String, String> m = new HashMap<String, String>();
            m.put("fieldName1", "四级1_" + i);
            m.put("fieldName2", "四级2_" + i);
            m.put("fieldName3", "四级3_" + i);
            m.put("fieldName4", "四级4_" + i);
            rowList.add(m);
        }
        ExcelPoiUtil excelTool = new ExcelPoiUtil("实体类（entity）多级表头表格");
        Map<String,String> param = ImmutableMap.<String, String>builder().put("id", "id").put("pid", "pid")
                .put("content", "content").put("fieldName", "fieldName").put("width", "width").build();
        List<ColEntity> titleData = excelTool.colEntityTransformer(titleList, param, "title");
        //HSSFWorkbook workbook = excelTool.exportWorkbook(titleData, rowList);
        //excelTool.save(workbook,"C:\\Users\\Administrator\\Desktop\\多级表头Obj1.xlsx");
        heads.put("实体类（entity）多级表头表格1",titleData);// 每个sheet的表头，sheet名称为key
        datas.put("实体类（entity）多级表头表格1",rowList);// 每个sheet的内容，sheet名称为key
        types.put("实体类（entity）多级表头表格1",0);// 每个sheet的样式类型，sheet名称为key
    }

    public static void 多级表头Obj2() throws Exception {
        List<TitleEntity> titleList = new ArrayList<>();
        titleList.add(new TitleEntity("title", null, "这里是title", null,20));
        // 固定的五项表头
        titleList.add(new TitleEntity("项目", "title", "项目", null,20));
        titleList.add(new TitleEntity("评分规则", "项目", "评分规则", null,20));
        titleList.add(new TitleEntity("评分标准", "评分规则", "评分标准", null,20));
        titleList.add(new TitleEntity("所在单位", "评分标准", "所在单位", "unit",15));
        titleList.add(new TitleEntity("所在部门", "评分标准", "所在部门", "dept",15));
        // 动态表头（实际项目需要根据数据库数据添加）
        int count = 0;
        for (int i = 0; i < 2; i++) {
            String xmId = "项目"+(i+1);
            TitleEntity xm = new TitleEntity(xmId, "title", xmId, null, 20);
            titleList.add(xm);
            for (int j = 0; j < 2; j++) {
                String gzId = "项目"+(i+1)+"-"+"规则"+(j+1);
                String bzId = "项目"+(i+1)+"-"+"标准"+(j+1);
                TitleEntity gz = new TitleEntity(gzId, xmId, gzId, null, 20);
                TitleEntity bz = new TitleEntity(bzId, gzId, String.valueOf(j), null, 20);
                TitleEntity sl = new TitleEntity(bzId+"_sl"+j, bzId, "数量", "sl"+count, 10);
                TitleEntity df = new TitleEntity(bzId+"_df"+j, bzId, "得分", "df"+count, 10);
                titleList.add(gz);
                titleList.add(bz);
                titleList.add(sl);
                titleList.add(df);
                count++;
            }
        }
        // 填充数据
        List<Map<String, String>> rowList = new ArrayList<>();
        for (int i = 0; i < 6; i++) {
            Map<String, String> m = new HashMap<String, String>();
            if (i<4){
                m.put("unit", "A单位");
                m.put("dept", "部门" + i);
            }else {
                m.put("unit", "B单位");
                m.put("dept", "部门" + i);
            }
            for (int j = 0; j < count; j++) {
                m.put("sl"+j, String.valueOf(j));
                m.put("df"+j, String.valueOf(j+i));
            }
            rowList.add(m);
        }
        ExcelPoiUtil excelTool = new ExcelPoiUtil("实体类（entity）多级表头表格");
        Map<String,String> param = ImmutableMap.<String, String>builder().put("id", "id").put("pid", "pid")
                .put("content", "content").put("fieldName", "fieldName").put("width", "width").build();
        List<ColEntity> titleData = excelTool.colEntityTransformer(titleList, param, "title");
        //HSSFWorkbook workbook = excelTool.exportWorkbook(titleData, rowList,Arrays.asList(0));
        //excelTool.save(workbook,"C:\\Users\\Administrator\\Desktop\\多级表头Obj2.xlsx");
        heads.put("实体类（entity）多级表头表格2",titleData);// 每个sheet的表头，sheet名称为key
        datas.put("实体类（entity）多级表头表格2",rowList);// 每个sheet的内容，sheet名称为key
        types.put("实体类（entity）多级表头表格2",0);// 每个sheet的样式类型，sheet名称为key
        mergeIndexs.put("实体类（entity）多级表头表格2",Arrays.asList(0));// 每个sheet的默认行高，sheet名称为key
    }

    public static void 纵向合并单元格() throws Exception {
        List<Map<String,String>> titleList=new ArrayList<>();
        Map<String,String> titleMap=new HashMap<String,String>();
        titleMap.put("id","11");titleMap.put("pid","0");titleMap.put("content","登录名");titleMap.put("fieldName","u_login_id");titleMap.put("width","20");
        Map<String,String> titleMap1=new HashMap<String,String>();
        titleMap1.put("id","1");titleMap1.put("pid","0");titleMap1.put("content","姓名");titleMap1.put("fieldName","u_name");titleMap1.put("width","20");
        Map<String,String> titleMap2=new HashMap<String,String>();
        titleMap2.put("id","2");titleMap2.put("pid","0");titleMap2.put("content","角色加部门");titleMap2.put("fieldName",null);titleMap2.put("width","20");
        Map<String,String> titleMap3=new HashMap<String,String>();
        titleMap3.put("id","3");titleMap3.put("pid","2");titleMap3.put("content","角色");titleMap3.put("fieldName","u_role");titleMap3.put("width","15");
        Map<String,String> titleMap4=new HashMap<String,String>();
        titleMap4.put("id","4");titleMap4.put("pid","2");titleMap4.put("content","部门");titleMap4.put("fieldName","u_dep");titleMap4.put("width","15");
        Map<String,String> titleMap5=new HashMap<String,String>();
        titleMap5.put("id","22");titleMap5.put("pid","0");titleMap5.put("content","角色加部门1");titleMap5.put("fieldName",null);titleMap5.put("width","20");
        Map<String,String> titleMap6=new HashMap<String,String>();
        titleMap6.put("id","22_1");titleMap6.put("pid","22");titleMap6.put("content","角色1");titleMap6.put("fieldName","u_role");titleMap6.put("width","10");
        Map<String,String> titleMap7=new HashMap<String,String>();
        titleMap7.put("id","22_2");titleMap7.put("pid","22");titleMap7.put("content","部门1");titleMap7.put("fieldName","u_dep");titleMap7.put("width","10");
        titleList.add(titleMap); titleList.add(titleMap1); titleList.add(titleMap2); titleList.add(titleMap3); titleList.add(titleMap4);
        titleList.add(titleMap5); titleList.add(titleMap6); titleList.add(titleMap7);
        // 单级的 行内数据
        List<Map<String, String>> rowList = new ArrayList<>();
        for (int i = 0; i < 10; i++) {
            Map<String, String> m = new HashMap<String, String>();
            m.put("u_login_id", "登录名zx" + i);
            if (i<6){
                m.put("u_login_id", "登录名zx1");
                m.put("u_name", i<3?"张三":"李四");

            }else {
                m.put("u_login_id", "登录名zx2");
                m.put("u_name", i<9?"王五":"赵六");
            }
            m.put("u_role", "角色" + i);
            m.put("u_dep", "部门" + i);
            m.put("u_type", "用户类型" + i);
            rowList.add(m);
        }
        ExcelPoiUtil excelTool = new ExcelPoiUtil("纵向合并单元格");
        Map<String,String> param = ImmutableMap.<String, String>builder().put("id", "id").put("pid", "pid")
                .put("content", "content").put("fieldName", "fieldName").put("width", "width").build();
        List<ColEntity> titleData = excelTool.colEntityTransformer(titleList,param, "0");
        //HSSFWorkbook workbook = excelTool.exportWorkbook(titleData, rowList,Arrays.asList(0,1));
        //excelTool.save(workbook,"C:\\Users\\Administrator\\Desktop\\纵向合并单元格.xlsx");
        heads.put("纵向合并单元格",titleData);// 每个sheet的表头，sheet名称为key
        datas.put("纵向合并单元格",rowList);// 每个sheet的内容，sheet名称为key
        types.put("纵向合并单元格",0);// 每个sheet的样式类型，sheet名称为key
        mergeIndexs.put("纵向合并单元格",Arrays.asList(0,1));// 每个sheet的默认行高，sheet名称为key
    }
}

最后

以上，终于是把项目里要的表格给导出来了！

实现代码的结构如图：

源码在这

最后感谢 这篇文章 的作者，也感谢这文章评论区提出bug的用户