将html table 转成 excel

 package com.sun.office.excel;

 /**
  * 跨行元素元数据
  *
  */
 public class CrossRangeCellMeta {

     public CrossRangeCellMeta(int firstRowIndex, int firstColIndex, int rowSpan, int colSpan) {
         super();
         this.firstRowIndex = firstRowIndex;
         this.firstColIndex = firstColIndex;
         this.rowSpan = rowSpan;
         this.colSpan = colSpan;
     }

     private int firstRowIndex;
     private int firstColIndex;
     private int rowSpan;// 跨越行数
     private int colSpan;// 跨越列数

     int getFirstRow() {
         return firstRowIndex;
     }

     int getLastRow() {
         return firstRowIndex + rowSpan - 1;
     }

     int getFirstCol() {
         return firstColIndex;
     }

     int getLastCol() {
         return firstColIndex + colSpan - 1;
     }

     int getColSpan(){
         return colSpan;
     }
 }

package com.sun.office.excel;

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

import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.math.NumberUtils;
import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFCellStyle;
import org.apache.poi.hssf.usermodel.HSSFFont;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.hssf.util.HSSFColor;
import org.apache.poi.ss.util.CellRangeAddress;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;

/**
 * 将html table 转成 excel
 *
 * 记录下来所占的行和列，然后填充合并
 */
public class ConvertHtml2Excel {
    public static void main(String[] args) {
        byte[] bs = null;
        try {
            FileInputStream fis = new FileInputStream(new File(ConvertHtml2Excel.class.getResource("./a.html").getPath()));
            bs = new byte[fis.available()];
            fis.read(bs);
            fis.close();
        } catch (Exception e1) {
            e1.printStackTrace();
        }
        String c = new String(bs);
        HSSFWorkbook wb = table2Excel(c);
        try {
            FileOutputStream fos = new FileOutputStream(new File("1.xls"));
            wb.write(fos);
            fos.flush();
            fos.close();
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

    /**
     * html表格转excel
     *
     * @param tableHtml 如
     *            <table>
     *            ..
     *            </table>
     * @return
     */
    public static HSSFWorkbook table2Excel(String tableHtml) {
        HSSFWorkbook wb = new HSSFWorkbook();
        HSSFSheet sheet = wb.createSheet();
        List<CrossRangeCellMeta> crossRowEleMetaLs = new ArrayList<CrossRangeCellMeta>();
        int rowIndex = 0;
        try {
            Document data = DocumentHelper.parseText(tableHtml);
            // 生成表头
            Element thead = data.getRootElement().element("thead");
            HSSFCellStyle titleStyle = getTitleStyle(wb);
            if (thead != null) {
                List<Element> trLs = thead.elements("tr");
                for (Element trEle : trLs) {
                    HSSFRow row = sheet.createRow(rowIndex);
                    List<Element> thLs = trEle.elements("th");
                    makeRowCell(thLs, rowIndex, row, 0, titleStyle, crossRowEleMetaLs);
                    rowIndex++;
                }
            }
            // 生成表体
            Element tbody = data.getRootElement().element("tbody");
            if (tbody != null) {
                HSSFCellStyle contentStyle = getContentStyle(wb);
                List<Element> trLs = tbody.elements("tr");
                for (Element trEle : trLs) {
                    HSSFRow row = sheet.createRow(rowIndex);
                    List<Element> thLs = trEle.elements("th");
                    int cellIndex = makeRowCell(thLs, rowIndex, row, 0, titleStyle, crossRowEleMetaLs);
                    List<Element> tdLs = trEle.elements("td");
                    makeRowCell(tdLs, rowIndex, row, cellIndex, contentStyle, crossRowEleMetaLs);
                    rowIndex++;
                }
            }
            // 合并表头
            for (CrossRangeCellMeta crcm : crossRowEleMetaLs) {
                sheet.addMergedRegion(new CellRangeAddress(crcm.getFirstRow(), crcm.getLastRow(), crcm.getFirstCol(), crcm.getLastCol()));
            }
        } catch (DocumentException e) {
            e.printStackTrace();
        }

        return wb;
    }

    /**
     * 生产行内容
     *
     * @return 最后一列的cell index
     */
    /**
     * @param tdLs th或者td集合
     * @param rowIndex 行号
     * @param row POI行对象
     * @param startCellIndex
     * @param cellStyle 样式
     * @param crossRowEleMetaLs 跨行元数据集合
     * @return
     */
    private static int makeRowCell(List<Element> tdLs, int rowIndex, HSSFRow row, int startCellIndex, HSSFCellStyle cellStyle,
            List<CrossRangeCellMeta> crossRowEleMetaLs) {
        int i = startCellIndex;
        for (int eleIndex = 0; eleIndex < tdLs.size(); i++, eleIndex++) {
            int captureCellSize = getCaptureCellSize(rowIndex, i, crossRowEleMetaLs);
            while (captureCellSize > 0) {
                for (int j = 0; j < captureCellSize; j++) {// 当前行跨列处理（补单元格）
                    row.createCell(i);
                    i++;
                }
                captureCellSize = getCaptureCellSize(rowIndex, i, crossRowEleMetaLs);
            }
            Element thEle = tdLs.get(eleIndex);
            String val = thEle.getTextTrim();
            if (StringUtils.isBlank(val)) {
                Element e = thEle.element("a");
                if (e != null) {
                    val = e.getTextTrim();
                }
            }
            HSSFCell c = row.createCell(i);
            if (NumberUtils.isNumber(val)) {
                c.setCellValue(Double.parseDouble(val));
                c.setCellType(HSSFCell.CELL_TYPE_NUMERIC);
            } else {
                c.setCellValue(val);
            }
            c.setCellStyle(cellStyle);
            int rowSpan = NumberUtils.toInt(thEle.attributeValue("rowspan"), 1);
            int colSpan = NumberUtils.toInt(thEle.attributeValue("colspan"), 1);
            if (rowSpan > 1 || colSpan > 1) { // 存在跨行或跨列
                crossRowEleMetaLs.add(new CrossRangeCellMeta(rowIndex, i, rowSpan, colSpan));
            }
            if (colSpan > 1) {// 当前行跨列处理（补单元格）
                for (int j = 1; j < colSpan; j++) {
                    i++;
                    row.createCell(i);
                }
            }
        }
        return i;
    }

    /**
     * 获得因rowSpan占据的单元格
     *
     * @param rowIndex 行号
     * @param colIndex 列号
     * @param crossRowEleMetaLs 跨行列元数据
     * @return 当前行在某列需要占据单元格
     */
    private static int getCaptureCellSize(int rowIndex, int colIndex, List<CrossRangeCellMeta> crossRowEleMetaLs) {
        int captureCellSize = 0;
        for (CrossRangeCellMeta crossRangeCellMeta : crossRowEleMetaLs) {
            if (crossRangeCellMeta.getFirstRow() < rowIndex && crossRangeCellMeta.getLastRow() >= rowIndex) {
                if (crossRangeCellMeta.getFirstCol() <= colIndex && crossRangeCellMeta.getLastCol() >= colIndex) {
                    captureCellSize = crossRangeCellMeta.getLastCol() - colIndex + 1;
                }
            }
        }
        return captureCellSize;
    }

    /**
     * 获得标题样式
     *
     * @param workbook
     * @return
     */
    private static HSSFCellStyle getTitleStyle(HSSFWorkbook workbook) {
        short titlebackgroundcolor = HSSFColor.GREY_25_PERCENT.index;
        short fontSize = 12;
        String fontName = "宋体";
        HSSFCellStyle style = workbook.createCellStyle();
        style.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER);
        style.setAlignment(HSSFCellStyle.ALIGN_CENTER);
        style.setBorderBottom((short) 1);
        style.setBorderTop((short) 1);
        style.setBorderLeft((short) 1);
        style.setBorderRight((short) 1);
        style.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);
        style.setFillForegroundColor(titlebackgroundcolor);// 背景色

        HSSFFont font = workbook.createFont();
        font.setFontName(fontName);
        font.setFontHeightInPoints(fontSize);
        font.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
        style.setFont(font);
        return style;
    }

    /**
     * 获得内容样式
     *
     * @param wb
     * @return
     */
    private static HSSFCellStyle getContentStyle(HSSFWorkbook wb) {
        short fontSize = 12;
        String fontName = "宋体";
        HSSFCellStyle style = wb.createCellStyle();
        style.setBorderBottom((short) 1);
        style.setBorderTop((short) 1);
        style.setBorderLeft((short) 1);
        style.setBorderRight((short) 1);

        HSSFFont font = wb.createFont();
        font.setFontName(fontName);
        font.setFontHeightInPoints(fontSize);
        style.setFont(font);
        return style;
    }
}

基本思路：

　　逐行遍历，记录下单元格所占的行和列，根据行列去填充空格，合并单元格