微信高级群发接口 根据分组进行群发消息类型老不对：报错

群发内容 不管是发图文还是文本，都提示 errcode":40008,"errmsg":"invalid message type 怎么搞也发不出去。

 public static String sendMsg(String data){

       String access_token= getAccess_token();
       String action = "https://api.weixin.qq.com/cgi-bin/message/mass/sendall?access_token="+access_token;
       try {
          URL url = new URL(action);
          HttpURLConnection http =   (HttpURLConnection) url.openConnection();    


          http.setRequestMethod("POST");        
          http.setRequestProperty("Content-Type","application/x-www-form-urlencoded");    
          http.setDoOutput(true);        
          http.setDoInput(true);
          System.setProperty("sun.net.client.defaultConnectTimeout", "30000");//连接超时30秒
          System.setProperty("sun.net.client.defaultReadTimeout", "30000"); //读取超时30秒
          http.connect();
          OutputStream os= http.getOutputStream();    
          os.write(data.getBytes("UTF-8"));//传入参数    
          os.flush();
          os.close();


          InputStream is =http.getInputStream();
          int size =is.available();
          byte[] jsonBytes =new byte[size];
          is.read(jsonBytes);
          String message=new String(jsonBytes,"UTF-8");
          return message;
          } catch (MalformedURLException e) {
              e.printStackTrace();
          } catch (IOException e) {
              e.printStackTrace();
          }    
       return "失败";
  }
 
 public static void main(String[] args) throws Exception
 {

String data="{\"filter\":{\"is_to_all\":false\"group_id\":\"0\"},\"text\":{\"content\":\"CONTENT\"},\"msgtype\":\"text\"}";      


String result = sendMsg(data);
                         System.out.println(result);


 }

有没有现成的例子，给个。。。。