如何在spring boot中用HttpHeaders下载excel文件？

在Spring Boot中使用HttpHeaders下载Excel文件的步骤如下：

首先，确保你已经引入了相关的依赖。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>

创建一个Controller类，并添加一个用于下载Excel文件的方法。例如：

import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import java.io.ByteArrayOutputStream;
import java.io.IOException;

@RestController
public class ExcelController {

    @GetMapping("/download")
    public ResponseEntity<byte[]> downloadExcel() throws IOException {
        // 创建一个工作簿
        Workbook workbook = new XSSFWorkbook();
        // 创建一个工作表
        Sheet sheet = workbook.createSheet("Sheet1");
        // 创建一行
        Row row = sheet.createRow(0);
        // 创建单元格并设置值
        Cell cell = row.createCell(0);
        cell.setCellValue("Hello, World!");

        // 将工作簿转换为字节数组
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        workbook.write(outputStream);
        byte[] excelBytes = outputStream.toByteArray();

        // 设置响应头
        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);
        headers.setContentDispositionFormData("attachment", "example.xlsx");

        return new ResponseEntity<>(excelBytes, headers,  HttpStatus.OK);
    }
}