JAVA restemplate 通过application/x-www-form-urlencoded访问

试了好几种方法都不行，要么返回空，要么报错。
最后就这种方法可以返回数据。      


  MultiValueMap<String, Object> psp = new LinkedMultiValueMap<>();
        psp.add("aaa", "xxxxx");
        psp.add("bbb", "xxxxxxxxxxxxx");
        psp.add("ccc", "xxxxxxxxx");
        psp.add("ddd", "xxxxxxxxxxxxxx");
        HttpHeaders headers = new HttpHeaders();
        headers.add("Content-Type", "application/x-www-form-urlencoded");
        HttpEntity<MultiValueMap<String, Object>> r = new HttpEntity<>(psp, headers);
        Map responseMessage = getInstance("utf-8").postForObject(PushServiceTypeConfig.MD_PUSH_URL1_PRODUCT, r, Map.class);
        System.out.println("输出了--------------------------------");
        System.out.println(responseMessage);

/**
 * 创建指定字符集的RestTemplate
 *
 * @param charset 编码
 * @return 返回结果
 */
public static RestTemplate getInstance(String charset) {
    RestTemplate restTemplate = new RestTemplate();
    restTemplate.getMessageConverters().add(new StringHttpMessageConverter(Charset.forName(charset)));
    return restTemplate;
}