package com.company.poi;

import org.apache.commons.io.FileUtils;
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.File;
import java.io.FileOutputStream;
import java.io.IOException;

public class Poi_WriteXlsxExcel {
    public static void main(String[] args) {
        String[] strings = {"id", "userName", "sex"};
        // 创建excel
        XSSFWorkbook hssfWorkbook = new XSSFWorkbook();
        // 创建sheet表
        XSSFSheet sheet = hssfWorkbook.createSheet();
        // 创建第一行
        XSSFRow row = sheet.createRow(0);
        XSSFCell cell = null;
        // 插入第一行
        for (int i = 0; i < strings.length; i++){
            cell = row.createCell(i);
            cell.setCellValue(strings[i]);
        }
        // 追加数据
        for (int i = 1; i < 10; i++){
            XSSFRow row1 = sheet.createRow(i);
            XSSFCell cell1 = row1.createCell(0);
            cell1.setCellValue("" + i);
            cell1 = row1.createCell(1);
            cell1.setCellValue("userName" + i);
            cell1 = row1.createCell(2);
            cell1.setCellValue("男");
        }
        // 创建一个excel文件
        File file = new File("E:\\Java_Test\\Poi_test01.xlsx");
        try {
            file.createNewFile();
            // 将excel存入流中
            FileOutputStream stream = FileUtils.openOutputStream(file);
            // 将内容写入
            hssfWorkbook.write(stream);
            stream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}

2.使用Poi读取xlsx格式的Escel

package com.company.poi;

import org.apache.commons.io.FileUtils;
import org.apache.poi.ss.usermodel.Cell;
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.File;
import java.io.IOException;

public class Poi_ReadXlsxExcel {
    public static void main(String[] args) {
        // 引入需要解析的excel文件
        File file = new File("E:\\Java_Test\\Poi_test01.xlsx");

        try {
            // 读取
            XSSFWorkbook xssfWorkbook = new XSSFWorkbook(FileUtils.openInputStream(file));
            // 获取sheet
            XSSFSheet xssfSheet = xssfWorkbook.getSheetAt(0);
            // 获取第一页
            int firstRowNum = 0;
            // 获取最后一页的数
            int lastRowNum = xssfSheet.getLastRowNum();
            for (int i = 0; i < lastRowNum; i++){
                XSSFRow xssfRow = xssfSheet.getRow(i);
                // 获取当前行最后单元格的序号
                int lastCellNum = xssfRow.getLastCellNum();
                for (int j = 0; j < lastCellNum; j++){
                    XSSFCell xssfCell = xssfRow.getCell(j);
                    String value = xssfCell.getStringCellValue();
                    // 当你的excel不只是String类型的时候 使用这个读取方式
//                    xssfCell.setCellType(Cell.CELL_TYPE_STRING);
//                    String value = xssfCell.getRichStringCellValue().getString();
                    System.out.print(value + " ");
                }
                System.out.println();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}