创建一个准备推送到另一个设备上的包含 NdefRecord 的 NdefMessage 对象

调用带有 NdefMessage 类型参数的 setNdefPushMessage() 方法，或者是在Activity的 onCreate()方法中调用 setNdefPushMessageCallback 方法来传递实现 NfcAdapter.CreateNdefMessageCallback 接口的对象。这两个方法都至少需要一个准备要启用Android Beam的Activity，以及一个可选的其他的活跃的Activity列表。

通常，如果你的Activity在任何时候都值推送相同的NDEF消息，那么当两个设备在通信范围内的时候，使用 setNdefPushMessage()就可以了。当你的应用程序要关注应用程序的当前内容，并想要根据用户在你的应用程序中的行为来推送NDEF消息时，就要使用setNdefPushMessageCallback方法。

下列示例代码演示了如何在activity的 onCreate()方法中调用 NfcAdapter.CreateNdefMessageCallback 方法（完整的示例请看 AndroidBeamDemo）。这个示例中还有帮助创建MIME记录的方法：-Create an object that contains ready to push NdefMessage NdefRecord another device

Call setNdefPushMessageCallback method call setNdefPushMessage with NdefMessage type parameter () method, or in the Activity onCreate () method to pass an object to achieve NfcAdapter.CreateNdefMessageCallback interface. Both methods require at least one preparation to enable Android Beam of Activity, and an optional list of other active Activity.

Generally, if your Activity at any time to push the same value NDEF messages, then when the two devices within communication range when using setNdefPushMessage () on it. When your application is going to focus on the current contents of the application, and you want the user behavior in your application to push NDEF message, then use setNdefPushMessageCallback methods.

NfcAdapter.CreateNdefMessageCallback method invocation following sample code demonstrates how the activity s onCreate () method (complete example, see AndroidBeamDemo). This example also help