uniapp中使用WebSocket问题

  this.socket = new WebSocket('ws://网址');
  this.socket.onopen = () => {
    console.log('WebSocket连接已打开');
    // 绑定群组
    let params = {
      form_id: '602',
      type: 'group',
      data: '602'
    };
    this.socket.send(JSON.stringify(params));
  };
  this.socket.onmessage = event => {
    console.log('收到消息：', event.data);
  };

** 上面代码可以收到消息， 下面代码收不到消息是怎么回事啊？**

  this.socketTask = uni.connectSocket({
    url: 'ws://地址',
    success: () => {
      console.log('WebSocket连接成功');
    },
    fail: () => {
      console.log('WebSocket连接失败');
    }
  });
  this.socketTask.onOpen(() => {
    console.log('WebSocket连接已打开');
    // 绑定群组
    let params = {
      form_id: '602',
      type: 'group',
      data: '602'
    };
    this.socketTask.send(JSON.stringify(params));
  });
  this.socketTask.onMessage(res => {
    const message = JSON.parse(res.data);
    console.log('message', message);
  });