Maven

     <!--http -->  
      <dependency>
          <groupId>org.apache.httpcomponents</groupId>
          <artifactId>httpclient</artifactId>
          <version>4.5.5</version>
     </dependency> 

随便找了一家短信验证码运营商，
对着提供的api文档
提供api需要的参数

/***
     * 手机端发送信息
     * 
     * @param mobile
     *            机号码，多个号码使用","分割
     * @param msg
     *            短信内容
     * @return 验证码
     */
    public static String smsCodeSend(String mobile) throws Exception {
            //用build方法来创建实例
            CloseableHttpClient  httpClient = HttpClientBuilder.create().build();
            HttpPost httpPost = new HttpPost(Const.REST_URL);
            Date day=new Date();    
            SimpleDateFormat df = new SimpleDateFormat("yyyyMMddHHmmss"); 
            String curTime = df.format(day);
            //加密
            String sig=MD5.md5(Const.ACCOUNT_SID+Const.AUTH_TOKEN+curTime);
            //添加头部信息
            httpPost.addHeader("Content-Type", "application/x-www-form-urlencoded;charset=utf-8");
            List<NameValuePair> nvps = new ArrayList<NameValuePair>();

            nvps.add(new BasicNameValuePair("accountSid", Const.ACCOUNT_SID));
            nvps.add(new BasicNameValuePair("templateid", Const.TEMPLATEID));
            nvps.add(new BasicNameValuePair("to", "186****6643"));
            nvps.add(new BasicNameValuePair("timestamp", curTime));
            nvps.add(new BasicNameValuePair("sig", sig));
            nvps.add(new BasicNameValuePair("param", "12345"));


            httpPost.setEntity(new UrlEncodedFormEntity(nvps, "utf-8"));
            HttpResponse response = httpClient.execute(httpPost);
            String a=EntityUtils.toString(response.getEntity(), "utf-8");
            JSONObject result = new JSONObject( );
            String code = (result!=null?result.get("respCode").toString():null);
            String obj = (result!=null?result.get("respDesc").toString():null);


            return code;
    }

然后，就可以了，就是这么简单