Java如何实现生成报表并将其导出为Excel

<dependencies>
    <!-- Apache POI for Excel (xlsx) -->
    <dependency>
        <groupId>org.apache.poi</groupId>
        <artifactId>poi-ooxml</artifactId>
        <version>5.2.3</version>
    </dependency>
    <!-- Apache POI for Excel (xls) -->
    <dependency>
        <groupId>org.apache.poi</groupId>
        <artifactId>poi</artifactId>
        <version>5.2.3</version>
    </dependency>
</dependencies>

import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
 
import java.io.*;
import java.util.*;
 
public class ExcelExportExample {
 
    public static void main(String[] args) {
        // 示例数据：可以从数据库、文件等获取
        List<Map<String, Object>> data = getData();
 
        // 创建Excel文件
        try (FileOutputStream fileOut = new FileOutputStream("report.xlsx")) {
            Workbook workbook = new XSSFWorkbook(); // 创建Excel工作簿
            Sheet sheet = workbook.createSheet("Report"); // 创建工作表
 
            // 创建表头
            createHeaderRow(sheet);
 
            // 填充数据
            fillData(sheet, data);
 
            // 将Excel文件写入磁盘
            workbook.write(fileOut);
            System.out.println("Excel file generated successfully.");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
 
    // 创建表头
    private static void createHeaderRow(Sheet sheet) {
        Row headerRow = sheet.createRow(0); // 表头行
        String[] columns = {"ID", "Name", "Age", "Department"};
 
        for (int i = 0; i < columns.length; i++) {
            Cell cell = headerRow.createCell(i);
            cell.setCellValue(columns[i]);
            // 设置表头字体为粗体
            CellStyle style = sheet.getWorkbook().createCellStyle();
            Font font = sheet.getWorkbook().createFont();
            font.setBold(true);
            style.setFont(font);
            cell.setCellStyle(style);
        }
    }
 
    // 填充数据到Excel表格
    private static void fillData(Sheet sheet, List<Map<String, Object>> data) {
        int rowNum = 1; // 从第二行开始填充数据
        for (Map<String, Object> rowData : data) {
            Row row = sheet.createRow(rowNum++);
            int cellNum = 0;
 
            // 填充每一列的数据
            row.createCell(cellNum++).setCellValue((Integer) rowData.get("id"));
            row.createCell(cellNum++).setCellValue((String) rowData.get("name"));
            row.createCell(cellNum++).setCellValue((Integer) rowData.get("age"));
            row.createCell(cellNum++).setCellValue((String) rowData.get("department"));
        }
    }
 
    // 示例数据，可以从数据库获取
    private static List<Map<String, Object>> getData() {
        List<Map<String, Object>> data = new ArrayList<>();
 
        // 模拟一些数据
        Map<String, Object> row1 = new HashMap<>();
        row1.put("id", 1);
        row1.put("name", "John Doe");
        row1.put("age", 30);
        row1.put("department", "IT");
 
        Map<String, Object> row2 = new HashMap<>();
        row2.put("id", 2);
        row2.put("name", "Jane Smith");
        row2.put("age", 25);
        row2.put("department", "HR");
 
        data.add(row1);
        data.add(row2);
 
        return data;
    }
}