基于主机的卡仿真或 HCE

Question

我想编写一个可以存储唯一 ID 的程序，然后将其作为 NFC 标签共享。我完全想编写可以使用移动设备而不是智能卡的程序。

我在许多网站和这里都读到过它，但我不明白如何将 ID 推送到我的应用程序以及如何通过 NFC 读取器设备共享此 ID

我不知道code below 是做什么的，他们的特点是什么

public class MainActivity extends Activity {

  public void onCreate(Bundle savedInstanceState) {
    pendingIntent = PendingIntent.getActivity(this, 0, new Intent(this,
                getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);
    filters = new IntentFilter[] { new IntentFilter(
                NfcAdapter.ACTION_TECH_DISCOVERED) };
    techLists = new String[][] { { "android.nfc.tech.IsoPcdA" } };
  }

  public void onResume() {
    super.onResume();
    if (adapter != null) {
      adapter.enableForegroundDispatch(this, pendingIntent, filters,
                    techLists);
    }
  }

  public void onPause() {
    super.onPause();
    if (adapter != null) {
      adapter.disableForegroundDispatch(this);
    }
  }

}

Answer 1

我建议您阅读有关 NFC 和 Android 的 ForegroundDispatcher 的更多信息。 首先，我将在基线中描述这段代码在做什么。

public class MainActivity extends Activity {

  public void onCreate(Bundle savedInstanceState) {

    //Here you define an intent that will be raised when a tag is received.
    pendingIntent = PendingIntent.getActivity(this, 0, new Intent(this,
                getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);

    //These are the tag conditions to throw the intent of above.
    //ACTION_TECH_DISCOVERED means the tag need to be of the type defined in the techlist.      
    filters = new IntentFilter[] { new IntentFilter(
                NfcAdapter.ACTION_TECH_DISCOVERED) };

    //As the name already says, this is your techlist
    techLists = new String[][] { { "android.nfc.tech.IsoPcdA" } };


  }

  public void onResume() {
    super.onResume();
    if (adapter != null) {

      //This enabled the foreground dispatching
      //It means that when a tag is detected of the type `IsoPcdA`. The `pendingIntent` will be given to the current activity
      adapter.enableForegroundDispatch(this, pendingIntent, filters,
                    techLists);
    }
  }

  public void onPause() {
    super.onPause();
    if (adapter != null) {

      //This is to disable the foreground dispatching. You don't want to send this intents to this activity when it isn't active
      adapter.disableForegroundDispatch(this);
    }
  }

}

由于这个ForegroundDispatching 抛出了一个新的intent，你需要重写onNewIntent 方法。 在这里您可以读取（和写入）标签。

@Override
public void onNewIntent(Intent intent)
{
    // Get the tag from the given intent
    Tag t = (Tag)intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);   
}       

祝你好运！

顺便说一句：这不是 HCE！上面的代码是一个读/写模式的例子，你可以读（或写）标签。