<dependencies>
    <!-- 舊的 .xls -->
    <!--<dependency>
      <groupId>org.apache.poi</groupId>
      <artifactId>poi</artifactId>
      <version>3.17</version>
    </dependency>-->
    <!-- 新的 .xlsx -->
    <dependency>
      <groupId>org.apache.poi</groupId>
      <artifactId>poi-ooxml</artifactId>
      <version>3.17</version>
    </dependency>
  </dependencies>

import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

import java.io.FileInputStream;
import java.io.IOException;

public class PoiTest {
  public static void main(String[] args) throws IOException {
    FileInputStream is = new FileInputStream("src/main/resources/test.xlsx");
    XSSFWorkbook workbook = new XSSFWorkbook(is);
    //讀取Sheet
    Sheet sheet = workbook.getSheetAt(0);
    Row row = sheet.getRow(0);
    //獲取最大行數
    int rownum = sheet.getPhysicalNumberOfRows();
    //獲取最大列數
    int colnum = row.getPhysicalNumberOfCells();
    for (int i = 0; i < rownum; i++) {
      //獲取第i行數據
      row = sheet.getRow(i);
      for (int j = 0; j < colnum; j++) {
        Cell cell = row.getCell(j);
        cell.setCellType(CellType.STRING);
        String cellText = cell.getStringCellValue();
        System.out.print(cellText + "\t");
      }
      System.out.println();
    }
  }
}

//獲取單元格
XSSFCell cell = row.getCell(0);
//獲取單元格數據
String cellValue = cell.getStringCellValue();

//獲取單元格
XSSFCell cell = row.getCell(0);
//設置單元格類型
cell.setCellType(CellType.STRING);
//獲取單元格數據
String cellValue = cell.getStringCellValue();