如何通过ajax使用Springboot @RestController下载文件

@RestController
public class FileDownloadController {

    @GetMapping("/download/{filename}")
    public ResponseEntity<byte[]> downloadFile(@PathVariable String filename) {
        try {
            // 根据文件名获取文件的绝对路径
            String filePath = "path/to/files/" + filename;
            File file = new File(filePath);

            // 设置Content-Disposition头部信息，指定文件名和下载方式
            HttpHeaders headers = new HttpHeaders();
            headers.setContentDispositionFormData("attachment", filename);

            // 将文件内容以字节数组的形式返回
            return ResponseEntity.ok()
                    .headers(headers)
                    .contentLength(file.length())
                    .contentType(MediaType.APPLICATION_OCTET_STREAM)
                    .body(Files.readAllBytes(file.toPath()));
        } catch (IOException e) {
            // 处理可能出现的异常
            e.printStackTrace();
            return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).build();
        }
    }
}

$.ajax({
    url: "/download/filename.txt",
    method: "GET",
    xhrFields: {
        responseType: 'blob'
    },
    success: function(data) {
        var blob = new Blob([data]);
        var url = URL.createObjectURL(blob);
        var a = document.createElement('a');
        a.href = url;
        a.download = "filename.txt";
        document.body.appendChild(a);
        a.click();
        document.body.removeChild(a);
    }
});