springboot数据库导出excel

Spring Boot可以使用Apache POI库将数据库数据导出为Excel文件。以下是实现步骤：

1. 添加Apache POI库的依赖

在pom.xml文件中添加以下依赖：

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

2. 创建Excel文件

使用Apache POI库创建Excel文件，可以使用以下代码：

Workbook workbook = new XSSFWorkbook();
Sheet sheet = workbook.createSheet("Sheet1");
Row headerRow = sheet.createRow(0);
headerRow.createCell(0).setCellValue("ID");
headerRow.createCell(1).setCellValue("Name");
headerRow.createCell(2).setCellValue("Age");

List<User> userList = userService.getAllUsers();
int rowNum = 1;
for (User user : userList) {
    Row row = sheet.createRow(rowNum++);
    row.createCell(0).setCellValue(user.getId());
    row.createCell(1).setCellValue(user.getName());
    row.createCell(2).setCellValue(user.getAge());
}

FileOutputStream fileOut = new FileOutputStream("userList.xlsx");
workbook.write(fileOut);
fileOut.close();
workbook.close();

3. 导出Excel文件

使用Spring Boot的RestController注解创建一个RESTful API，将Excel文件作为响应返回给客户端，可以使用以下代码：

@GetMapping("/export")
public void exportToExcel(HttpServletResponse response) throws IOException {
    response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
    response.setHeader("Content-Disposition", "attachment; filename=userList.xlsx");

    Workbook workbook = new XSSFWorkbook();
    Sheet sheet = workbook.createSheet("Sheet1");
    Row headerRow = sheet.createRow(0);
    headerRow.createCell(0).setCellValue("ID");
    headerRow.createCell(1).setCellValue("Name");
    headerRow.createCell(2).setCellValue("Age");

    List<User> userList = userService.getAllUsers();
    int rowNum = 1;
    for (User user : userList) {
        Row row = sheet.createRow(rowNum++);
        row.createCell(0).setCellValue(user.getId());
        row.createCell(1).setCellValue(user.getName());
        row.createCell(2).setCellValue(user.getAge());
    }

    OutputStream outputStream = response.getOutputStream();
    workbook.write(outputStream);
    outputStream.close();
    workbook.close();
}

在浏览器中访问http://localhost:8080/export，将会下载名为userList.xlsx的Excel文件。