poi 生成excel文件.xls或者.xls实例，包括日期写入处理

import java.io.File;
import java.io.FileOutputStream;
import java.util.Date;

import org.apache.poi.hssf.usermodel.HSSFCellStyle;
import org.apache.poi.hssf.usermodel.HSSFDataFormat;
import org.apache.poi.hssf.usermodel.HSSFFont;
import org.apache.poi.hssf.util.HSSFColor;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.CellStyle;
import org.apache.poi.ss.usermodel.Font;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

public class ExportExcel {

<span style="white-space:pre">	</span>private String excelPath = "E://haha.xlsx";

    public static void main(String[] args) throws Exception{
    	ExportExcel excel = new ExportExcel();
        if(excel.createExcelFile()) {
            System.out.println("data.xlsx is created successfully.");
        }
    }
    public boolean createExcelFile() {
   	 int flag=0;
        boolean isCreateSuccess = false;
        Workbook workbook = null;
        try {
            workbook = new XSSFWorkbook();
        }catch(Exception e) {
            System.out.println("It cause Error on CREATING excel workbook: ");
            e.printStackTrace();
        }
        if(workbook != null) {
            Sheet sheet = workbook.createSheet("testdata");
            Row row0 = sheet.createRow(0);
            row0.setHeight((short)1000);//设置单元格宽和高
            sheet.setColumnWidth((short) 0, (short) 250);
            for(int i = 0; i < 13; i++) {
                Cell cell_1 = row0.createCell(i, Cell.CELL_TYPE_STRING);
                flag=0;
                CellStyle style = getStyle(workbook,flag,0);
                cell_1.setCellStyle(style);
                //此处是用来设置第一行标题
                switch (i) {
					case 0:
						cell_1.setCellValue("主题(Subject)");
						break;
					case 1:
						cell_1.setCellValue("用例引入ID");
						break;
					case 2:
						cell_1.setCellValue("用例修改状态");
						break;
					case 3:
						cell_1.setCellValue("用例名称");
						break;
					case 4:
						cell_1.setCellValue("用例等级");
						break;
					case 5:
						cell_1.setCellValue("预置条件");
						break;
					case 6:
						cell_1.setCellValue("操作步骤");
						break;
					case 7:
						cell_1.setCellValue("预期结果");
						break;
					case 8:
						cell_1.setCellValue("注释");
						break;
					case 9:
						cell_1.setCellValue("设计者");
						break;
					case 10:
						cell_1.setCellValue("用例修改者");
						break;
					case 11:
						cell_1.setCellValue("用例编写时间");
						break;
					case 12:
						cell_1.setCellValue("用例修改时间");
						break;
             }
                sheet.autoSizeColumn(i);
            }

            for (int rowNum = 1; rowNum < 20; rowNum++) {
                Row row = sheet.createRow(rowNum);
                row.setHeight((short)1500);
                for(int i = 0; i < 13; i++) {
               	 flag=1;
               	 CellStyle style = getStyle(workbook,flag,i);
		            Cell cell = row.createCell(i, Cell.CELL_TYPE_STRING);
		            cell.setCellStyle(style);
		            switch (i) {
						case 0:
							cell.setCellValue("hhh");
							break;
						case 1:
							cell.setCellValue(1212);
							break;
						case 2:
							cell.setCellValue("qqq");
							break;
						case 3:
							cell.setCellValue("dddd");
							break;
						case 4:
							cell.setCellValue("level_2");
							break;
						case 5:
							cell.setCellValue("ssss");
							break;
						case 6:
							cell.setCellValue("sss");
							break;
						case 7:
							cell.setCellValue("ggg");
							break;
						case 8:
							cell.setCellValue("hhh");
							break;
						case 9:
							cell.setCellValue("jjj");
							break;
						case 10:
							cell.setCellValue("kkjl");
							break;
						case 11:
							cell.setCellValue(new Date());
							break;
						case 12:
							cell.setCellValue(new Date());
							break;
						}
                }
            }
            try {
                FileOutputStream outputStream = new FileOutputStream(excelPath);
                workbook.write(outputStream);
                outputStream.flush();
                outputStream.close();
                isCreateSuccess = true;
            } catch (Exception e) {
                System.out.println("It cause Error on WRITTING excel workbook: ");
                e.printStackTrace();
            }
        }
        File sss = new File(excelPath);
        System.out.println(sss.getAbsolutePath());
        return isCreateSuccess;
    }
    private CellStyle getStyle(Workbook workbook,int flag,int i){//flag是用来判断是否是标题，从而来设置不同的标题，i是用来判断是某列，来对某列的样式进行设定
        CellStyle style = workbook.createCellStyle();
        style.setAlignment(CellStyle.ALIGN_CENTER); 
        style.setVerticalAlignment(CellStyle.VERTICAL_CENTER);
        style.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);//给单元格设置底色，如果要给单元格设置颜色，必须先设置底色才行，否则颜色出不来
        if(flag==0){
       	 style.setFillForegroundColor(HSSFColor.GREY_25_PERCENT.index);//设置标题颜色
        }else {
       	 style.setFillForegroundColor(HSSFColor.PALE_BLUE.index);//设置正文背景色
		}

        if(i==11||i==12){//因为第12行13行是要写入日期，所要预先设置日期格式，然后直接设置，注意是date类型
			style.setDataFormat(HSSFDataFormat.getBuiltinFormat("m/d/yy"));//设置日期格式
		}

        // 设置单元格字体
        Font headerFont = workbook.createFont(); // 字体
        headerFont.setFontHeightInPoints((short)14);
        if(flag==0){
       	 headerFont.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);//粗体显示
        }
        headerFont.setFontName("宋体");
        style.setFont(headerFont);
        style.setWrapText(true);

        // 设置单元格边框及颜色
        style.setBorderBottom(HSSFCellStyle.BORDER_THIN); //下边框
        style.setBorderLeft(HSSFCellStyle.BORDER_THIN);//左边框
        style.setBorderTop(HSSFCellStyle.BORDER_THIN);//上边框
        style.setBorderRight(HSSFCellStyle.BORDER_THIN);//右边框
        style.setWrapText(true);
        return style;
    }

}