/**
 * @author: BNTang
 */
@Controller
public class MyFirstController {
    @RequestMapping("/download")
    public ResponseEntity<byte[]> download(HttpSession httpSession) throws Exception {
        // 1.获取 ServletContext
        ServletContext servletContext = httpSession.getServletContext();

        // 2.获取路径
        String realPath = servletContext.getRealPath("/images/zdy.jpg");

        // 3.创建一个输入流
        FileInputStream fileInputStream = new FileInputStream(realPath);
        byte[] bytes = new byte[fileInputStream.available()];

        // 4.将文件流读取到数组当中
        fileInputStream.read(bytes);

        // 5.创建请求头
        HttpHeaders httpHeaders = new HttpHeaders();

        // 6.对文件名进行编码
        String fileEncode = URLEncoder.encode("周冬雨.jpg", "UTF-8");

        // 7.告诉浏览器以附件的形式下载文件
        httpHeaders.add("Content-Disposition", "attachment;filename=" + fileEncode);

        // 8.设置响应码
        HttpStatus httpStatus = HttpStatus.OK;

        ResponseEntity<byte[]> responseEntity = new ResponseEntity<>(bytes, httpHeaders, httpStatus);

        // 9.关闭流
        fileInputStream.close();

        return responseEntity;
    }
}