POI进行跨行需要用到对象HSSFSheet对象，现在就当我们程序已经定义了一个HSSFSheet对象sheet。

跨第1行第1个到第2个单元格的操作为 
sheet.addMergedRegion(new Region(0,(short)0,0,(short)1));

跨第1行第1个到第2行第1个单元格的操作为 
sheet.addMergedRegion(new Region(0,(short)0,1,(short)0));

重点注意事项： 
1.单元格CELL和ROW对象下标都是从0开始的。 
2.单元格合并时Region(1,2,3,4)第1个值的行号必须要比3位置的行号小，如果大于3就不能正常合并单元格 
3.合并单元格的时候要合并的单单元格必须先创建，这样方便后面再次获取这个单元格来填充数据，主要就是因为合并时不能由后向前进行合并引起的。

import java.io.IOException;

import org.apache.poi.hssf.usermodel.HSSFCell;

import org.apache.poi.hssf.usermodel.HSSFCellStyle;

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.Region;

public class ExcelTest {

/**

* @param args

*/

public static void main(String[] args) throws IOException {

try {

HSSFWorkbook wb = new HSSFWorkbook();

HSSFSheet sheet = wb.createSheet("new   sheet");

HSSFCellStyle style = wb.createCellStyle(); // 样式对象

style.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER);// 垂直

style.setAlignment(HSSFCellStyle.ALIGN_CENTER);// 水平

HSSFRow row = sheet.createRow((short) 0);

HSSFRow row2 = sheet.createRow((short) 1);

sheet.addMergedRegion(new Region(0, (short) 0, 1, (short) 0));

HSSFCell ce = row.createCell((short) 0);

ce.setEncoding(HSSFCell.ENCODING_UTF_16);// 中文处理

ce.setCellValue("项目\\日期"); // 表格的第一行第一列显示的数据

ce.setCellStyle(style); // 样式，居中

int num = 0;

for (int i = 0; i < 9; i++) { // 循环9次，每一次都要跨单元格显示

// 计算从那个单元格跨到那一格

int celln = 0;

int celle = 0;

if (i == 0) {

celln = 0;

celle = 1;

} else {

celln = (i * 2);

celle = (i * 2 + 1);

}

// 单元格合并

// 四个参数分别是：起始行，起始列，结束行，结束列

sheet.addMergedRegion(new Region(0, (short) (celln + 1), 0,

(short) (celle + 1)));

HSSFCell cell = row.createCell((short) (celln + 1));

cell.setCellValue("merging" + i); // 跨单元格显示的数据

cell.setCellStyle(style); // 样式

// 不跨单元格显示的数据，如：分两行，上一行分别两格为一格，下一行就为两格，“数量”，“金额”

HSSFCell cell1 = row2.createCell((short) celle);

HSSFCell cell2 = row2.createCell((short) (celle + 1));

cell1.setEncoding(HSSFCell.ENCODING_UTF_16);

cell1.setCellValue("数量");

cell1.setCellStyle(style);

cell2.setEncoding(HSSFCell.ENCODING_UTF_16);

cell2.setCellValue("金额");

cell2.setCellStyle(style);

num++;

}

// 在后面加上合计百分比

// 合计 在最后加上，还要跨一个单元格

sheet.addMergedRegion(new Region(0, (short) (2 * num + 1), 0,

(short) (2 * num + 2)));

HSSFCell cell = row.createCell((short) (2 * num + 1));

cell.setEncoding(HSSFCell.ENCODING_UTF_16);

cell.setCellValue("合计");

cell.setCellStyle(style);

HSSFCell cell1 = row2.createCell((short) (2 * num + 1));

HSSFCell cell2 = row2.createCell((short) (2 * num + 2));

cell1.setEncoding(HSSFCell.ENCODING_UTF_16);

cell1.setCellValue("数量");

cell1.setCellStyle(style);

cell2.setEncoding(HSSFCell.ENCODING_UTF_16);

cell2.setCellValue("金额");

cell2.setCellStyle(style);

// 百分比 同上

sheet.addMergedRegion(new Region(0, (short) (2 * num + 3), 0,

(short) (2 * num + 4)));

HSSFCell cellb = row.createCell((short) (2 * num + 3));

cellb.setEncoding(HSSFCell.ENCODING_UTF_16);

cellb.setCellValue("百分比");

cellb.setCellStyle(style);

HSSFCell cellb1 = row2.createCell((short) (2 * num + 3));

HSSFCell cellb2 = row2.createCell((short) (2 * num + 4));

cellb1.setEncoding(HSSFCell.ENCODING_UTF_16);

cellb1.setCellValue("数量");

cellb1.setCellStyle(style);

cellb2.setEncoding(HSSFCell.ENCODING_UTF_16);

cellb2.setCellValue("金额");

cellb2.setCellStyle(style);

/***这里是问题的关键，将这个工作簿写入到一个流中就可以输出相应的名字，这里需要写路径就ok了。

FileOutputStream fileOut = new FileOutputStream("workbook.xls");

wb.write(fileOut);

fileOut.close();

**/

/**第二种是输出到也面中的excel名称

* pName="栏目统计表";

response.reset();

response.setContentType("application/x-msdownload");

response.setHeader("Content-Disposition","attachment; filename="+new String(pName.getBytes("gb2312"),"ISO-8859-1")+".xls");

ServletOutputStream outStream=null;

try{

outStream = response.getOutputStream();

wb.write(outStream);

}catch(Exception e)

{

e.printStackTrace();

}finally{

outStream.close();

}

* */

System.out.print("OK");

} catch (Exception ex) {

ex.printStackTrace();

}

}

}