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我正在尝试将 Android Beam 合并到我的应用程序中。但是，我需要为我的应用扩展另一个类而不是 Activity。当我尝试这样做时：

public class SomeClass extends AnotherActivity implements
            CreateNdefMessageCallback{

Android Beam 根本不工作，Touch to Beam 不显示。但是，当我这样做时：

public class SomeClass extends Activity implements
            CreateNdefMessageCallback{

Android Beam 工作正常。AnotherActivity 扩展了一些其他活动，这些活动最终扩展了 Activity 本身，所以我不知道为什么 Android Beam 在第一种情况下不起作用。有谁知道为什么会这样？

这是更多原始的 Android Beam 不工作代码供参考。

import android.app.Activity;
import android.content.Intent;
import android.nfc.NdefMessage;
import android.nfc.NdefRecord;
import android.nfc.NfcAdapter;
import android.nfc.NfcAdapter.CreateNdefMessageCallback;
import android.nfc.NfcEvent;
import android.os.Bundle;
import android.os.Handler;
import android.os.Parcelable;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import android.view.View;
import android.view.View.OnClickListener;

public class SomeClass extends AnotherActivity implements
        CreateNdefMessageCallback{
    NfcAdapter mNfcAdapter;
    TextView mInfoText;
    private static final int MESSAGE_SENT = 1;
    private NdefMessage message;
    private TextView textView;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Check for available NFC Adapter
        mNfcAdapter = NfcAdapter.getDefaultAdapter(this);

        if (mNfcAdapter == null) {
            Toast.makeText(this, "NFC is not available", Toast.LENGTH_LONG)
                    .show();
            finish();
            return;
        }

        // Register callback to set NDEF message
        mNfcAdapter.setNdefPushMessageCallback(this, this);

    }

    /**
     * Implementation for the CreateNdefMessageCallback interface
     */

    @Override
    public NdefMessage createNdefMessage(NfcEvent event) {
        String text = ("Beam me up, Android!\n\n" +
                "Beam Time: " + System.currentTimeMillis());
        NdefMessage msg = new NdefMessage(
                new NdefRecord[] {
                    NdefRecord.createMime(
                            "application/vnd.com.example.android.beam",
                            text.getBytes())
                });
        return msg;
    }


    @Override
    public void onResume() {
        super.onResume();
        // Check to see that the Activity started due to an Android Beam
        if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(getIntent().getAction())) {
            processIntent(getIntent());
        }
    }

    @Override
    public void onNewIntent(Intent intent) {
        // onResume gets called after this to handle the intent
        setIntent(intent);
    }

    /**
     * Parses the NDEF Message from the intent and prints to the TextView
     */
    void processIntent(Intent intent) {
        Parcelable[] rawMsgs = intent
                .getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);
        // only one message sent during the beam
        NdefMessage msg = (NdefMessage) rawMsgs[0];
        // record 0 contains the MIME type, record 1 is the AAR, if present
        mInfoText.setText(new String(msg.getRecords()[0].getPayload()));
    }
}

我在 DDMS LogCat 中检查了两者之间的差异。这是使用 AnotherActivity 的日志（NFC 不起作用）

07-14 13:53:10.317: W/NFC-LLC(608): LLC length mis-match
07-14 13:53:12.747: I/NFC-HCI(608): I'm P2P Passive Target @ 212 kb/s
07-14 13:53:12.754: D/NFCJNI(608): Discovered P2P Initiator
07-14 13:53:12.754: D/NFCJNI(608): 46 
07-14 13:53:12.754: D/NFCJNI(608): 66 
07-14 13:53:12.754: D/NFCJNI(608): 6d 
07-14 13:53:12.754: D/NFCJNI(608): 01 
07-14 13:53:12.754: D/NFCJNI(608): 01 
07-14 13:53:12.754: D/NFCJNI(608): 11 
07-14 13:53:12.754: D/NFCJNI(608): 03 
07-14 13:53:12.754: D/NFCJNI(608): 02 
07-14 13:53:12.754: D/NFCJNI(608): 00 
07-14 13:53:12.754: D/NFCJNI(608): 13 
07-14 13:53:12.754: D/NFCJNI(608): 04 
07-14 13:53:12.754: D/NFCJNI(608): 01 
07-14 13:53:12.754: D/NFCJNI(608): 96 
07-14 13:53:12.754: D/NfcService(608): LLCP Activation message
07-14 13:53:12.762: I/NFCJNI(608): LLCP Link activated (LTO=150, MIU=128, OPTION=0x00, WKS=0x13)
07-14 13:53:12.762: I/NfcP2pLinkManager(608): LLCP activated
07-14 13:53:12.762: D/NfcP2pLinkManager(608): onP2pInRange()
07-14 13:53:12.778: D/NfcP2pLinkManager(608): onP2pSendConfirmationRequested()
07-14 13:53:12.934: I/NfcExecutionEnvironment(2915): NFCEE.open locked: stack=[NfcEventServiceWorker] openTid=263 nfceeOpened=false tryLock=0ms
07-14 13:53:12.942: D/NFCJNI(608): Unable to open SE connection, device already connected to a P2P peer or a Tag
07-14 13:53:13.950: D/NFCJNI(608): Unable to open SE connection, device already connected to a P2P peer or a Tag
07-14 13:53:14.958: D/NFCJNI(608): Unable to open SE connection, device already connected to a P2P peer or a Tag
07-14 13:53:15.965: D/NFCJNI(608): Unable to open SE connection, device already connected to a P2P peer or a Tag
07-14 13:53:16.981: D/NFCJNI(608): Unable to open SE connection, device already connected to a P2P peer or a Tag
07-14 13:53:17.989: D/NFCJNI(608): Unable to open SE connection, device already connected to a P2P peer or a Tag
07-14 13:53:18.997: D/NFCJNI(608): Unable to open SE connection, device already connected to a P2P peer or a Tag
07-14 13:53:20.012: D/NFCJNI(608): Unable to open SE connection, device already connected to a P2P peer or a Tag
07-14 13:53:20.801: I/NFCJNI(608): LLCP Link deactivated
07-14 13:53:20.809: D/NfcService(608): LLCP Link Deactivated message. Restart polling loop.
07-14 13:53:20.809: I/NfcP2pLinkManager(608): LLCP deactivated.
07-14 13:53:21.184: E/NfcExecutionEnvironment(2915): NFCEE.open() re-enabling card emulation
07-14 13:53:21.192: I/NfcAdapterExtras(2915): Wakelock WakeLock{41439a78 held=true, refCount=1} acquired 1405364001194 ms
07-14 13:53:21.192: I/NfcAdapterExtras(2915): Wakelock WakeLock{41439a78 held=true, refCount=1} released 1405364001198 ms elapsed 4 ms
07-14 13:53:21.192: I/NfcAdapterExtras(2915): Wakelock WakeLock{41439a78 held=true, refCount=1} acquired 1405364001199 ms
07-14 13:53:21.200: I/NfcAdapterExtras(2915): Wakelock WakeLock{41439a78 held=true, refCount=1} released 1405364001202 ms elapsed 3 ms
07-14 13:53:21.200: I/NfcExecutionEnvironment(2915): NFCEE.open  ++: stack=[NfcEventServiceWorker, SecureElement] openTid=263 nfceeOpened=true holdCount=2
07-14 13:53:21.200: I/NfcExecutionEnvironment(2915): NFCEE.open  ++: stack=[NfcEventServiceWorker, SecureElement, SecureElement] openTid=263 nfceeOpened=true holdCount=3
07-14 13:53:21.200: I/NfcExecutionEnvironment(2915): NFCEE.open  ++: stack=[NfcEventServiceWorker, SecureElement, SecureElement, ControllerApplet] openTid=263 nfceeOpened=true holdCount=4
07-14 13:53:21.262: I/NfcExecutionEnvironment(2915): NFCEE.close --: stack=[NfcEventServiceWorker, SecureElement, SecureElement, ControllerApplet] openTid=263 nfceeOpened=true holdCount=4
07-14 13:53:21.262: I/NfcExecutionEnvironment(2915): NFCEE.close --: stack=[NfcEventServiceWorker, SecureElement, SecureElement] openTid=263 nfceeOpened=true holdCount=3
07-14 13:53:21.262: I/NfcExecutionEnvironment(2915): NFCEE.close --: stack=[NfcEventServiceWorker, SecureElement] openTid=263 nfceeOpened=true holdCount=2
07-14 13:53:21.262: W/NfcEventServiceWorker(2915): Payments are activated failure: com.google.android.apps.embeddedse.iso7816.SecureElementAppletFileNotFoundException: ControllerApplet: SELECT a0000004762010: statusWord=0x6a82 (File Not Found)
07-14 13:53:21.262: I/NfcExecutionEnvironment(2915): NFCEE.open  ++: stack=[NfcEventServiceWorker, MifareManagerImpl] openTid=263 nfceeOpened=true holdCount=2
07-14 13:53:21.270: I/NfcExecutionEnvironment(2915): NFCEE.open  ++: stack=[NfcEventServiceWorker, MifareManagerImpl, MifareManagerImpl] openTid=263 nfceeOpened=true holdCount=3
07-14 13:53:21.270: I/NfcExecutionEnvironment(2915): NFCEE.close --: stack=[NfcEventServiceWorker, MifareManagerImpl, MifareManagerImpl] openTid=263 nfceeOpened=true holdCount=3
07-14 13:53:21.270: I/NfcExecutionEnvironment(2915): NFCEE.open  ++: stack=[NfcEventServiceWorker, MifareManagerImpl, MifareApplet] openTid=263 nfceeOpened=true holdCount=3
07-14 13:53:21.340: I/NfcExecutionEnvironment(2915): NFCEE.close --: stack=[NfcEventServiceWorker, MifareManagerImpl, MifareApplet] openTid=263 nfceeOpened=true holdCount=3
07-14 13:53:21.348: I/NfcExecutionEnvironment(2915): NFCEE.close --: stack=[NfcEventServiceWorker, MifareManagerImpl] openTid=263 nfceeOpened=true holdCount=2
07-14 13:53:21.364: D/NfcService(608): NFC-EE ON
07-14 13:53:21.372: D/NfcService(608): NFC-C ON
07-14 13:53:21.395: I/NfcExecutionEnvironment(2915): NFCEE.close closed: stack=[NfcEventServiceWorker] openTid=263 nfceeOpened=true tryLock=0ms session=8460ms
07-14 13:53:21.559: D/NfcP2pLinkManager(608): Debounce timeout
07-14 13:53:21.559: D/NfcP2pLinkManager(608): onP2pOutOfRange()
07-14 13:53:21.770: I/NfcEventServiceWorker(2915): Waiting ...
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1 回答 1

2

我发现了问题。在 AnotherActivity （或者在我的情况下，类 C，其中 AnotherActivity 扩展 A，扩展 B，扩展 C）我有以下代码行。

getWindow().setFlags(LayoutParams.FLAG_SECURE, LayoutParams.FLAG_SECURE);

这将禁用对 Android Beam UI（“Touch to Beam”）功能至关重要的屏幕截图。如果没有 UI，Android Beam 将根本无法工作。解决方案是在 AnotherActivity 中执行以下操作：

getWindow().clearFlags(LayoutParams.FLAG_SECURE);

现在一切正常。

于 2014-07-17T17:43:30.237 回答