java如何读取excel

读取Excel文件的常用方法

在Java中读取Excel文件通常使用Apache POI或JExcelAPI等库。以下是几种常见的实现方式：

使用Apache POI读取.xlsx文件（Excel 2007+格式）

Apache POI是处理Microsoft Office文档的流行库。对于.xlsx格式，使用XSSFWorkbook类：

import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFRow;
import org.apache.poi.xssf.usermodel.XSSFCell;
import java.io.FileInputStream;

public class ReadExcel {
    public static void main(String[] args) {
        try (FileInputStream file = new FileInputStream("example.xlsx")) {
            XSSFWorkbook workbook = new XSSFWorkbook(file);
            XSSFSheet sheet = workbook.getSheetAt(0);

            for (int i = 0; i <= sheet.getLastRowNum(); i++) {
                XSSFRow row = sheet.getRow(i);
                for (int j = 0; j < row.getLastCellNum(); j++) {
                    XSSFCell cell = row.getCell(j);
                    System.out.print(cell.toString() + "\t");
                }
                System.out.println();
            }
            workbook.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

使用Apache POI读取.xls文件（Excel 97-2003格式）

对于旧版Excel文件，使用HSSFWorkbook类：

import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFCell;
import java.io.FileInputStream;

public class ReadOldExcel {
    public static void main(String[] args) {
        try (FileInputStream file = new FileInputStream("example.xls")) {
            HSSFWorkbook workbook = new HSSFWorkbook(file);
            HSSFSheet sheet = workbook.getSheetAt(0);

            for (int i = 0; i <= sheet.getLastRowNum(); i++) {
                HSSFRow row = sheet.getRow(i);
                for (int j = 0; j < row.getLastCellNum(); j++) {
                    HSSFCell cell = row.getCell(j);
                    System.out.print(cell.toString() + "\t");
                }
                System.out.println();
            }
            workbook.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

使用EasyExcel读取大文件

对于大型Excel文件，阿里巴巴的EasyExcel库更高效：

import com.alibaba.excel.EasyExcel;
import java.util.List;

public class ReadLargeExcel {
    public static void main(String[] args) {
        String fileName = "large_example.xlsx";
        EasyExcel.read(fileName, DemoData.class, new DemoDataListener()).sheet().doRead();
    }
}

class DemoDataListener implements AnalysisEventListener<DemoData> {
    public void invoke(DemoData data, AnalysisContext context) {
        System.out.println(data);
    }
    public void doAfterAllAnalysed(AnalysisContext context) {}
}

处理不同单元格类型

读取单元格时需要处理不同类型的数据：

switch (cell.getCellType()) {
    case STRING:
        System.out.print(cell.getStringCellValue());
        break;
    case NUMERIC:
        System.out.print(cell.getNumericCellValue());
        break;
    case BOOLEAN:
        System.out.print(cell.getBooleanCellValue());
        break;
    default:
        System.out.print("");
}

Maven依赖配置

使用Apache POI需要添加以下依赖：

<dependency>
    <groupId>org.apache.poi</groupId>
    <artifactId>poi</artifactId>
    <version>5.2.3</version>
</dependency>
<dependency>
    <groupId>org.apache.poi</groupId>
    <artifactId>poi-ooxml</artifactId>
    <version>5.2.3</version>
</dependency>

对于EasyExcel：

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>easyexcel</artifactId>
    <version>3.1.3</version>
</dependency>

注意事项

• 处理大文件时考虑使用流式读取（如EasyExcel）
• 关闭工作簿和输入流防止资源泄漏
• 处理空单元格和异常情况
• 考虑使用try-with-resources语句自动关闭资源