通过接口得到json数据

private Optional<String> getResponseJson(RestApi restApi){
    try {
        HttpHeaders httpHeaders = new HttpHeaders();
        httpHeaders.setContentType(MediaType.APPLiCATION_JSON);
        if(Optional.ofNullable(restApi.getAuthorizaton()).isPresent()){
            httpHeaders.add("Authorization",restApi.getAuthrization());
        }
        HttpEntity<String> requestEntity = new HttpEntity<>(null,httpHeaders);
        ResponeseEntity<String> responseEntity = restTemplate.exchange(restApi.getUrl(),restApi.getHttpMethod(),requestEntity,String.class);
        return Optional.of(responseEntity.getBody());

    }catch (Exception e){
        log.error();
        return Optional.empty();
    }
}
private Optional<String> getResponseJson(RestApi restApi,DataMapping dataMapping,Map<String,Object> params){
    try {
        HttpHeaders httpHeaders = new HttpHeaders();
        httpHeaders.setContentType(MediaType.APPLiCATION_JSON);
        if(Optional.ofNullable(restApi.getAuthorizaton()).isPresent()){
            httpHeaders.add("Authorization",restApi.getAuthrization());
        }
        Map<String,Object> data = new HashMap<>();
        if(dataMapping.getSourceDimCode() instanceof  Map){
            data.put((Map)dataMapping.getSourceDimCode());
        }else{
            data.putAll("sourceDimCode",dataMapping.getSourceDimCode());
        }
        if(Optional.ofNullable(params).isPresent()){
            data.putAll(params);
        }
        String body = render(Optional.ofNullable(restApi.getBody()).orElse(""),data);
        String url = render(restApi.getUrl(),data);
        HttpEntity<String> requestEntity = new HttpEntity<>(body,httpHeaders);
        ResponeseEntity<String> responseEntity = restTemplate.exchange(restApi.getUrl(),restApi.getHttpMethod(),requestEntity,String.class);
        return Optional.of(responseEntity.getBody());

    }catch (Exception e){
        log.error();
        return Optional.empty();
    }
}

private String render(String template,Map<String,Object> data){
    try {
        StringTemplateResourceLoader  resourceLoader = new StringTemplateResourceLoader();
        Configuration cfg = Configuration.defaultConfiguration();
        GroupTemplate gt = new GroupTemplate(resourceLoader,cfg);
        org.beetl.core.Template t = gt.getTemplate(template);
        t.binding(data);
        String str = t.render();
        return str;
        
    }catch (IoException e){
        throw  new AppException();
    }
}