poi – 生成excel时使表头比较醒目、好看

		CellStyle style = sheet.getWorkbook().createCellStyle();
		//置成黄色
		style.setFillForegroundColor(IndexedColors.YELLOW.getIndex());
		style.setFillPattern(CellStyle.SOLID_FOREGROUND);

		//表头的边界线清晰可见
		style.setBorderBottom(HSSFCellStyle.BORDER_THIN);
		style.setBorderTop(HSSFCellStyle.BORDER_THIN);
		style.setBorderRight(HSSFCellStyle.BORDER_THIN);
		style.setBorderLeft(HSSFCellStyle.BORDER_THIN);

		Row header = sheet.createRow(0);
		int columnIndex = 0;
		for (...) {
			Cell cell = createCell(header, columnIndex);
			cell.setCellValue(headerText);
			cell.setCellStyle(style);
			//表头cell的宽度适应文字
			sheet.autoSizeColumn(columnIndex);
			columnIndex++;
		}