java-poi操作笔记

row表示行，cell表示row中的第几个cell

package sample.Utils;

import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.DateUtil;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;

public  class excelUtils {

    //读取excel
    public static Workbook readExcel(String filePath){
        Workbook wb = null;
        if(filePath==null){
            return null;
        }
        String extString = filePath.substring(filePath.lastIndexOf("."));
        InputStream is = null;
        try {
            is = new FileInputStream(filePath);
            if(".xls".equals(extString)){
                return wb = new HSSFWorkbook(is);
            }else if(".xlsx".equals(extString)){
                return wb = new XSSFWorkbook(is);
            }else{
                return wb = null;
            }

        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return wb;
    }
    public static Object getCellFormatValue(Cell cell){
        Object cellValue = null;
        if(cell!=null){
            //判断cell类型
            switch(cell.getCellType()){
                case Cell.CELL_TYPE_NUMERIC:{
                    cellValue = String.valueOf(cell.getNumericCellValue());
                    break;
                }
                case Cell.CELL_TYPE_FORMULA:{
                    //判断cell是否为日期格式
                    if(DateUtil.isCellDateFormatted(cell)){
                        //转换为日期格式YYYY-mm-dd
                        cellValue = cell.getDateCellValue();
                    }else{
                        //数字
                        cellValue = String.valueOf(cell.getNumericCellValue());
                    }
                    break;
                }
                case Cell.CELL_TYPE_STRING:{
                    cellValue = cell.getRichStringCellValue().getString();
                    break;
                }
                default:
                    cellValue = "";
            }
        }else{
            cellValue = "";
        }
        return cellValue;
    }
  public static void writeExcel(String filePath,String sheet1Name,int row1,int one,int two,int three,int four, String onecontent,String twocontent,String threecontent,String fourcontent){
        FileInputStream inputStream = null;
        try {
            inputStream = new FileInputStream(filePath);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }

        Workbook workbook = null;
        try {
            workbook = new XSSFWorkbook(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
        Sheet sheet = workbook.getSheet(sheet1Name);
        Row row = sheet.createRow(row1);

        Cell cell1 =  row.createCell(one);
        cell1.setCellValue(onecontent);

        Cell cell24 =  row.createCell(two);
        cell24.setCellValue(twocontent);

        Cell cell25 =  row.createCell(three);
        cell25.setCellValue(threecontent);

        Cell cell26 =  row.createCell(four);
        cell26.setCellValue(fourcontent);

        // 写入数据
        try (FileOutputStream outputStream = new FileOutputStream(filePath)) {
            workbook.write(outputStream);
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (workbook != null) {
                    workbook.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

}