将RichText与TextSpan和GestureRecognizer一起使用。使用GestureRecognizer它可以检测 点击 ， 双击 ， 长按 等。

Widget build(BuildContext context) {
    TextStyle defaultStyle = TextStyle(color: Colors.grey, fontSize: 20.0);
    TextStyle linkStyle = TextStyle(color: Colors.blue);
    return RichText(
      text: TextSpan(
        style: defaultStyle,
        children: <TextSpan>[
          TextSpan(text: 'By clicking Sign Up, you agree to our '),
          TextSpan(
              text: 'Terms of Service',
              style: linkStyle,
              recognizer: TapGestureRecognizer()
                ..onTap = () {
                  print('Terms of Service"');
                }),
          TextSpan(text: ' and that you have read our '),
          TextSpan(
              text: 'Privacy Policy',
              style: linkStyle,
              recognizer: TapGestureRecognizer()
                ..onTap = () {
                  print('Privacy Policy"');
                }),
        ],
      ),
    );
  }