poi的excel解析工具类

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import org.apache.commons.lang.StringUtils;
import org.apache.commons.lang.time.DateFormatUtils;
import org.apache.commons.lang.time.DateUtils;
import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFDateUtil;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
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;

import java.io.IOException;
import java.io.InputStream;
import java.text.DecimalFormat;
import java.text.SimpleDateFormat;
import java.util.*;

/**
 * Created by shea on 2018/9/20.
 */
public class ExcelUtil {
    private static DecimalFormat df = new DecimalFormat("0");             //数字格式，防止长数字成为科学计数法形式，或者int变为double形式
    //获取excel解析引擎
    public static Workbook getExcelEngine(String fileName, InputStream in){
        Workbook workbook = null;
        try {
            if(fileName.endsWith("xls")){
                workbook=new HSSFWorkbook(in);
            }else {
                workbook=new XSSFWorkbook(in);
            }
            return workbook;
        }catch (Exception e){
            e.printStackTrace();
        }
        return null;
    }
    //判断单元格类型,返回指定值
    public static String getCellValue(Cell cell){
        int cellType = cell.getCellType();
        String res="";
        switch (cellType){
            case 0:
                if(HSSFDateUtil.isCellDateFormatted(cell)){
                    Date date = cell.getDateCellValue();
                    res = DateFormatUtils.format(date, "yyyy-MM");
                }else {
                    cell.setCellType(0);
                    res =df.format(cell.getNumericCellValue());
                }

                break;
            case 1:
                cell.setCellType(1);
                res = cell.getStringCellValue();
                break;
            case 2://公式---也强转为string
                cell.setCellType(1);
                res = cell.getStringCellValue();
                break;
            case 3://空值
                cell.setCellType(3);
                res = "";
            case 4://布尔值
                cell.setCellType(4);
                res = String.valueOf( cell.getBooleanCellValue());
                break;
            default:
               res="";
                break;
        }
        return res;
    }
    /**
     * 获取指定行列的值
     * @param sheet
     * @param rowNum 行--- 0表示第一行
     * @param colNum 列--- 0表示第一列
     * @return
     */
    public static String getRowCell(Sheet sheet, int rowNum, int colNum){
        Row row = sheet.getRow(rowNum);
        Cell cell = row.getCell(colNum);
        return  getCellValue(cell);
    }

    /**
     * execl解析----统一封装到list
     * @param sheet
     * @param rowBegin 起始行
     * @param colBegin 起始列
     * @param maxRows   最大行
     * @param maxCols  最大列
     * @return
     * @throws IOException
     */
    public static List  adjustExcelParse(Sheet sheet, int rowBegin,int colBegin,int maxRows,int maxCols) {
        //将每一个单元格，设置为 String类型
        //解析
        try {
            Row row;
            Cell cell;
            String[] arr;
            List datas = new ArrayList();
            //判断最大行数是否为-1，若为-1，则取最大行值
            int endRows=sheet.getLastRowNum()+1;
            if(-1!=maxRows){
                endRows=maxRows;
            }
            for(int i=rowBegin-1;i