java的实体类固定如何获取多的xlsx的所有数据

要获取多个xlsx文件的所有数据，可以使用Apache POI库来读取Excel文件。具体步骤如下：

1. 引入Apache POI库的依赖，例如在Maven项目中可以添加以下依赖：

<dependency>
    <groupId>org.apache.poi</groupId>
    <artifactId>poi-ooxml</artifactId>
    <version>4.1.2</version>
</dependency>

2. 创建一个Excel文件读取器，例如：

import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

public class ExcelReader {
    public static List<List<String>> readExcel(File file) throws IOException {
        List<List<String>> data = new ArrayList<>();
        try (FileInputStream inputStream = new FileInputStream(file)) {
            Workbook workbook = new XSSFWorkbook(inputStream);
            Sheet sheet = workbook.getSheetAt(0);
            for (int rowIndex = 0; rowIndex <= sheet.getLastRowNum(); rowIndex++) {
                Row row = sheet.getRow(rowIndex);
                if (row == null) {
                    continue;
                }
                List<String> rowData = new ArrayList<>();
                for (int columnIndex = 0; columnIndex < row.getLastCellNum(); columnIndex++) {
                    Cell cell = row.getCell(columnIndex, Row.MissingCellPolicy.RETURN_BLANK_AS_NULL);
                    String cellValue = "";
                    if (cell != null) {
                        switch (cell.getCellType()) {
                            case STRING:
                                cellValue = cell.getStringCellValue();
                                break;
                            case NUMERIC:
                                cellValue = String.valueOf(cell.getNumericCellValue());
                                break;
                            case BOOLEAN:
                                cellValue = String.valueOf(cell.getBooleanCellValue());
                                break;
                            case FORMULA:
                                cellValue = String.valueOf(cell.getCellFormula());
                                break;
                            default:
                                cellValue = "";
                        }
                    }
                    rowData.add(cellValue);
                }
                data.add(rowData);
            }
        }
        return data;
    }
}

3. 遍历所有要读取的Excel文件，例如：

import java.io.File;
import java.io.IOException;
import java.util.List;

public class Main {
    public static void main(String[] args) throws IOException {
        File[] files = new File("./data").listFiles();
        for (File file : files) {
            if (file.isFile() && file.getName().endsWith(".xlsx")) {
                List<List<String>> data = ExcelReader.readExcel(file);
                System.out.println("File: " + file.getName());
                for (List<String> rowData : data) {
                    System.out.println(rowData);
                }
                System.out.println();
            }
        }
    }
}

其中，"./data"是存放所有要读取的Excel文件的目录。