java下载指定文件并返回给前端返回流文件的实现步骤

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;
import javax.servlet.http.HttpServletResponse;

public class FileDownloadUtil {

    public static void downloadFile(String filePath, String fileName, HttpServletResponse response) throws IOException {
        // 设置响应的Header参数
        response.reset();
        response.setContentType("application/octet-stream");
        response.setHeader("Content-Disposition", "attachment;filename=" + fileName);

        // 读取文件内容并将其转换为字节数组
        FileInputStream fis = new FileInputStream(filePath);
        BufferedInputStream bis = new BufferedInputStream(fis);
        byte[] buffer = new byte[bis.available()];
        bis.read(buffer);

        // 设置文件的MIME类型
        response.setContentType("application/octet-stream");

        // 设置响应的Content-Disposition头部信息
        response.setHeader("Content-Disposition", "attachment;filename=" + fileName);

        // 将字节数组写入响应的输出流
        OutputStream os = response.getOutputStream();
        BufferedOutputStream bos = new BufferedOutputStream(os);
        bos.write(buffer);
        bos.flush();

        // 关闭输出流
        bos.close();
        bis.close();
    }
}