如何在HTML中调用jar applet文件

Question

我已经用Java复制了一个非常简单的applet（仅是一条书面消息）并创建了一个jar文件。我使用以下代码调用了jar文件，但是当我在浏览器中打开文件时，什么都没有出现（除了标题）。我在犯什么新手错误？

private ResponseEntity<String> exchange(String url, HttpMethod method, HttpEntity<?> httpEntity,
                                           Class<?> class1, Map<String, String> paramMap) {
        ResponseEntity<String> responseEntity = null;
        try {
            responseEntity = restTemplate.exchange(url, method, httpEntity, String.class, paramMap);
        }catch(HttpClientErrorException e) {
            responseEntity = new ResponseEntity<>(e.getResponseBodyAsString(), HttpStatus.BAD_REQUEST);
        }catch(HttpServerErrorException e) {
            responseEntity = new ResponseEntity<>(e.getResponseBodyAsString(), HttpStatus.INTERNAL_SERVER_ERROR);
            throw e;
        }catch(Exception e) {
            responseEntity = new ResponseEntity<>(e.getMessage(), HttpStatus.INTERNAL_SERVER_ERROR);
            throw e;
        }
        return responseEntity;
    }