import java.io.FileOutputStream;
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
*/
@SuppressWarnings("deprecation")
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, 2, (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);

FileOutputStream fileOut = new FileOutputStream("workbook.xls");
wb.write(fileOut);
fileOut.close();
System.out.print("OK");
} catch (Exception ex) {
ex.printStackTrace();
}

}

}

======================================================

用到的jar包

poi-3.8.jar
poi-examples-3.8.jar
poi-excelant-3.8.jar
poi-ooxml-3.8.jar
poi-ooxml-schemas-3.8.jar
poi-scratchpad-3.8.jar

======================================================

效果

java 导出excel(复杂案例)