使用poi导出excel 一张表 三个sheet 数据为三个不同的对象集合 写个案例

好的，下面是使用poi导出excel的案例代码，该excel文件包含三个sheet，每个sheet分别对应三个不同的对象集合。

import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

public class ExcelExport {
    public static void main(String[] args) {
        List<User> userList = new ArrayList<>();
        List<Car> carList = new ArrayList<>();
        List<Book> bookList = new ArrayList<>();

        // 生成测试数据
        for (int i = 1; i <= 10; i++) {
            User user = new User(i, "User" + i, 20 + i);
            userList.add(user);

            Car car = new Car(i, "Brand" + i, "Model" + i);
            carList.add(car);

            Book book = new Book(i, "Book" + i, "Author" + i);
            bookList.add(book);
        }

        try (Workbook workbook = new XSSFWorkbook()) {
            // 创建三个sheet
            Sheet userSheet = workbook.createSheet("User");
            Sheet carSheet = workbook.createSheet("Car");
            Sheet bookSheet = workbook.createSheet("Book");

            // 导出用户数据
            int rowNum = 0;
            Row userHeader = userSheet.createRow(rowNum++);
            userHeader.createCell(0).setCellValue("ID");
            userHeader.createCell(1).setCellValue("Name");
            userHeader.createCell(2).setCellValue("Age");

            for (User user : userList) {
                Row row = userSheet.createRow(rowNum++);
                row.createCell(0).setCellValue(user.getId());
                row.createCell(1).setCellValue(user.getName());
                row.createCell(2).setCellValue(user.getAge());
            }

            // 导出汽车数据
            rowNum = 0;
            Row carHeader = carSheet.createRow(rowNum++);
            carHeader.createCell(0).setCellValue("ID");
            carHeader.createCell(1).setCellValue("Brand");
            carHeader.createCell(2).setCellValue("Model");

            for (Car car : carList) {
                Row row = carSheet.createRow(rowNum++);
                row.createCell(0).setCellValue(car.getId());
                row.createCell(1).setCellValue(car.getBrand());
                row.createCell(2).setCellValue(car.getModel());
            }

            // 导出书籍数据
            rowNum = 0;
            Row bookHeader = bookSheet.createRow(rowNum++);
            bookHeader.createCell(0).setCellValue("ID");
            bookHeader.createCell(1).setCellValue("Name");
            bookHeader.createCell(2).setCellValue("Author");

            for (Book book : bookList) {
                Row row = bookSheet.createRow(rowNum++);
                row.createCell(0).setCellValue(book.getId());
                row.createCell(1).setCellValue(book.getName());
                row.createCell(2).setCellValue(book.getAuthor());
            }

            // 写入到文件
            try (FileOutputStream outputStream = new FileOutputStream("test.xlsx")) {
                workbook.write(outputStream);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

class User {
    private int id;
    private String name;
    private int age;

    public User(int id, String name, int age) {
        this.id = id;
        this.name = name;
        this.age = age;
    }

    public int getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }
}

class Car {
    private int id;
    private String brand;
    private String model;

    public Car(int id, String brand, String model) {
        this.id = id;
        this.brand = brand;
        this.model = model;
    }

    public int getId() {
        return id;
    }

    public String getBrand() {
        return brand;
    }

    public String getModel() {
        return model;
    }
}

class Book {
    private int id;
    private String name;
    private String author;

    public Book(int id, String name, String author) {
        this.id = id;
        this.name = name;
        this.author = author;
    }

    public int getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public String getAuthor() {
        return author;
    }
}

以上代码会生成一个名为 `test.xlsx` 的excel文件，其中包含三个sheet，分别对应三个不同的对象集合。每个sheet中的数据都是从相应的对象集合中生成的，具体的数据格式可以根据需求进行修改。