poi处理excel2007和处理excel2003文件

import org.apache.log4j.Logger;
import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFDateUtil;
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.xssf.usermodel.XSSFCell;
import org.apache.poi.xssf.usermodel.XSSFRow;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.text.DecimalFormat;
import java.text.SimpleDateFormat;
import java.util.ArrayList;


public class ExcelUtil {
    static Logger logger = Logger.getLogger(ExcelUtil.class);
    /**
     * 默认单元格内容为数字时格式
     */
    private static DecimalFormat df = new DecimalFormat("0");
    /**
     * 默认单元格格式化日期字符串
     */
    private static SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    /**
     * 格式化数字
     */
    private static DecimalFormat nf = new DecimalFormat("0.00");

    public static ArrayList> readExcel(File file) {
        if (file == null) {
            return null;
        }
        if (file.getName().toLowerCase().endsWith("xlsx")) {
            //处理ecxel2007
            return readExcel2007(file);
        } else {
            //处理ecxel2003
            return readExcel2003(file);
        }
    }

    /**
     * @param file
     * @return 将返回结果存储在ArrayList内，存储结构与二位数组类似
     * lists.get(0).get(0)表示过去Excel中0行0列单元格
     */
    public static ArrayList> readExcel2003(File file) {
        try {
            ArrayList> rowList = new ArrayList>();
            ArrayList