RestTemplate请求时设置请求头，请求参数，请求体。

public static <T> ResponseEntity<T> request(String url,
                                            HttpMethod httpMethod,
                                            Class<T> responseType,
                                            Map<String,String> headers,
                                            Map<String,String> params,
                                            Map<String,String> body) {
    

        //设置请求参数
        MultiValueMap<String, String> paramsMap = new LinkedMultiValueMap<>();

        if(CollUtil.isNotEmpty(params)){
    
            params.forEach(paramsMap::add);
        }

        UriComponentsBuilder builder = UriComponentsBuilder.fromHttpUrl(url);
        URI uri = builder.queryParams(paramsMap).build().encode().toUri();

        // 设置请求头
        HttpHeaders httpHeaders = new HttpHeaders();
        // 传递请求体时必须设置
        httpHeaders.add("Content-Type", "application/json");

        if( CollUtil.isNotEmpty(headers) ){
    
            headers.forEach(httpHeaders::add);
        }

        // 设置请求头和请求体
        HttpEntity<String> httpEntity = new HttpEntity<>(JSONUtil.toJsonStr(body), httpHeaders);

        return restTemplate.exchange(uri,httpMethod,httpEntity,responseType);
    }