Apache POI单元格读取指南：理解层级结构与正确导航

import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.ss.usermodel.WorkbookFactory;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

// 假设有一个Excel文件路径
File excelFile = new File("path/to/your/excel.xlsx");
Workbook workbook = null;
try (FileInputStream fis = new FileInputStream(excelFile)) {
    workbook = WorkbookFactory.create(fis);
} catch (IOException e) {
    System.err.println("文件读取或创建工作簿时发生IO错误: " + e.getMessage());
    e.printStackTrace();
} catch (Exception e) {
    System.err.println("创建工作簿时发生未知错误: " + e.getMessage());
    e.printStackTrace();
}

if (workbook == null) {
    System.out.println("无法加载工作簿，请检查文件路径和权限。");
    return;
}

import org.apache.poi.ss.usermodel.Sheet;

Sheet sheet = workbook.getSheetAt(0); // 获取第一个工作表 (索引为0)
// 或者通过名称获取：
// Sheet sheet = workbook.getSheet("Sheet1");

if (sheet == null) {
    System.out.println("指定的工作表不存在，请检查索引或名称。");
    // 关闭工作簿以释放资源
    try { workbook.close(); } catch (IOException e) { e.printStackTrace(); }
    return;
}

import org.apache.poi.ss.usermodel.Row;

int rowIndex = 2; // 例如，获取第三行 (索引为2)
Row row = sheet.getRow(rowIndex);

if (row == null) {
    System.out.println("指定行不存在，可能为空行或超出范围。");
    // 关闭工作簿
    try { workbook.close(); } catch (IOException e) { e.printStackTrace(); }
    return;
}

import org.apache.poi.ss.usermodel.Cell;

int cellIndex = 3; // 例如，获取第四列的单元格 (索引为3)
Cell cell = row.getCell(cellIndex);

if (cell == null) {
    System.out.println("指定单元格不存在，可能为空单元格。");
    // 关闭工作簿
    try { workbook.close(); } catch (IOException e) { e.printStackTrace(); }
    return;
}

// 简单打印单元格值
System.out.println("Cell value is: " + cell.toString());

// 更健壮的类型判断和值获取
switch (cell.getCellType()) {
    case STRING:
        System.out.println("String value: " + cell.getStringCellValue());
        break;
    case NUMERIC:
        if (org.apache.poi.ss.usermodel.DateUtil.isCellDateFormatted(cell)) {
            System.out.println("Date value: " + cell.getDateCellValue());
        } else {
            System.out.println("Numeric value: " + cell.getNumericCellValue());
        }
        break;
    case BOOLEAN:
        System.out.println("Boolean value: " + cell.getBooleanCellValue());
        break;
    case FORMULA:
        System.out.println("Formula value: " + cell.getCellFormula());
        // 如果需要计算公式结果，可以使用FormulaEvaluator
        // FormulaEvaluator evaluator = workbook.getCreationHelper().createFormulaEvaluator();
        // System.out.println("Evaluated formula value: " + evaluator.evaluate(cell).getStringValue());
        break;
    case BLANK:
        System.out.println("Blank cell.");
        break;
    case ERROR:
        System.out.println("Error cell.");
        break;
    default:
        System.out.println("Unknown cell type.");
}

// 完成操作后，关闭工作簿
try {
    workbook.close();
} catch (IOException e) {
    e.printStackTrace();
}