指定Excel合并列，将列中相邻有相同数据的单元个合并

数据列表导出，并按指定列进行合并

1. 组织参数代码

   String export(rows){
   def list = []
   list.add(['熔炼炉号','材质','钢水总重kg','铸件单重','钢水单重','件数','图号','铸件名称',
             '电炉班组','造型班组','铸造号','化学成分和性能控制代号'
   ])
   rows.each{
       list.add([
               it.furnace,
               it.texture,
               it.total_molten_steel_weight,
               it.rough_weight,
               it.molten_steel_weight,
               it.num,
               it.drawing,
               it.mater_name,
               it.yljz_dept_name,
               it.zxhx_dept_name,
               it.casting,
               it.standard_code
       ])
   }
   //合并列
   def megeIndex = null
   megeIndex = [0,1,2,11]
   }

2. 计算同一列相同值，并对其它值求和

   //合并同熔炼炉号的钢水重量
   private void calcTotal(List<Record> castList) {
   def i = -1
   //前一个炉号,不用null避免数据炉号有null
   def pre_furnace = "✾"
   //钢水总重
   def total_molten_steel_weight = 0
   castList.eachWithIndex { it, index ->
       def molten_steel_weight = it.molten_steel_weight
       if(molten_steel_weight==null){
           molten_steel_weight=0
       }
       if (it.furnace == pre_furnace && it.furnace!=null) {
           total_molten_steel_weight += molten_steel_weight
       } else {
           if (index > 0) {
               castList[index - 1].total_molten_steel_weight = total_molten_steel_weight
           }
           i++
           pre_furnace = it.furnace
           total_molten_steel_weight = molten_steel_weight
       }
       if (index == castList.size() - 1) {
           castList[index].total_molten_steel_weight = total_molten_steel_weight
       }
   }
   if (castList != null && castList.size() > 0) {
       def reverseList = castList.reverse();
       reverseList.eachWithIndex { it, index ->
           if (it.total_molten_steel_weight == null && index > 0) {
               it.total_molten_steel_weight = reverseList[index - 1].total_molten_steel_weight
           }
       }
   }
   }

3. 导出excel代码

   /**
   * 导出excel
   * @param list 数据列，第一行是表头   
   * @param path 文件存放路径   
   * @param mergeIndex 需要合并的列号
   */
   public static void ExportExcel(List<Object> list, String path, List<Integer> mergeIndex) {
   File dbfFile = new File(path);
   FileOutputStream out = null;
   Workbook wb = null;
   try {
       if (!dbfFile.exists() || dbfFile.isDirectory()) {
           dbfFile.createNewFile();
       }
       out = new FileOutputStream(dbfFile);
       if (path.toLowerCase().endsWith(".xls")) {
           wb = new HSSFWorkbook();
       } else {
           wb = new XSSFWorkbook();
       }
       boolean mergeList = mergeIndex!=null&&mergeIndex.size()>0;
       Sheet sheet = wb.createSheet("Sheet1");
       sheet.setDefaultColumnWidth(15);
       sheet.setDefaultRowHeight((short) (20 * 20));
       CellStyle style = wb.createCellStyle();
       style.setAlignment(CellStyle.ALIGN_CENTER);
       style.setVerticalAlignment(CellStyle.VERTICAL_CENTER);
       //存储合并的比对值:key 列,value[0] 比对值,value[1] 起始行
       HashMap<Integer,Object[]> compareMap = new HashMap<>();
       for (int r = 0; r < list.size(); r++) {
           List dataRow = (List) list.get(r);
           if (dataRow != null) {
               Row row = sheet.createRow(r);
               for (int c = 0; c < dataRow.size(); c++) {
                   Object dataCell = dataRow.get(c);
                   if (dataCell != null) {
                       Cell cell = row.createCell(c);
                       cell.setCellStyle(style);
                       cell.setCellValue(dataCell.toString());
                   }
                   //判断列是否要合并
                   if(mergeList&&mergeIndex.contains(c) && r>0){
                       Object[] compare = compareMap.get(c);
                       if(compare!=null){//该列有比对值
                           if(!compare[0].equals(dataCell)){//当前值和比对值不同,则将前面列进行合并
                               //合并单元格范围
                               CellRangeAddress cra=new CellRangeAddress((int) compare[1],r-1,c,c);
                               sheet.addMergedRegion(cra);
                               if(dataCell==null){//当前值为空则移除比对值
                                   compareMap.remove(c);
                               }else {//替换比对值
                                   compareMap.put(c,new Object[]{dataCell,r});
                               }
                           }
                       }else if(dataCell!=null){
                           //该列没有比对值，且当前值不为空，则将当前值存为比对值供后面比对
                           compareMap.put(c,new Object[]{dataCell,r});
                       }
                       //如果当前行是最后一行，直接合并
                       if(r==list.size()-1 && compare!=null){
                           //合并单元格范围
                           CellRangeAddress cra=new CellRangeAddress((int) compare[1],r-1,c,c);
                           sheet.addMergedRegion(cra);
                       }
                   }
               }
           }
       }
       wb.write(out);
   } catch (IOException e) {
       e.printStackTrace();
   } finally {
       if(wb!=null){
           try {
               wb.close();
           } catch (IOException e) {
               e.printStackTrace();
           }
       }
       if(out!=null){
           try {
               out.close();
           } catch (IOException e) {
               e.printStackTrace();
           }
       }
   }
   }