后端

@GetMapping("/test")
public void test( HttpServletResponse response) {
    response.addHeader("test-header-title", Base64.getEncoder().encodeToString("强调".getBytes(StandardCharsets.UTF_8)));
}

前端

let value = res.headers["test-header-title"]
let title = new TextDecoder().decode(Uint8Array.from(atob(value), (c) => c.charCodeAt(0)))