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您好我正在尝试从 NFC 标签读取数据。读取数据没有问题。但我必须扫描我的标签两次才能显示数据。当我第一次扫描标签时，它会启动应用程序但不读取数据。所以要读取数据，我必须再次扫描我的标签。那么我应该怎么做才能在我扫描我的标签后立即启动应用程序并从标签中读取数据。该应用程序是从标签中读取数据并更改我的 android 手机的配置文件。这是我的代码.. 谢谢....

public class Read extends Activity {

    Tag detectedTag;
    TextView txtType,txtSize,txtWrite,txtRead;
    Button btn_back;
    NfcAdapter nfcAdapter;
    IntentFilter[] readTagFilters;
    PendingIntent pendingIntent;
    byte[] new_payload;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);

        requestWindowFeature(Window.FEATURE_CUSTOM_TITLE);
        setContentView(R.layout.read);
        getWindow().setFeatureInt(Window.FEATURE_CUSTOM_TITLE, R.layout.custom_title);

         nfcAdapter = NfcAdapter.getDefaultAdapter();
         detectedTag =getIntent().getParcelableExtra(NfcAdapter.EXTRA_TAG);
        txtType  = (TextView) findViewById(R.id.txtType);
        txtSize  = (TextView) findViewById(R.id.txtsize);
        txtRead  = (TextView) findViewById(R.id.txt_read);

        pendingIntent = PendingIntent.getActivity(getApplicationContext(), 0, 
                new Intent(this,getClass()).
                addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);

        IntentFilter tagDetected = new IntentFilter(NfcAdapter.ACTION_TAG_DISCOVERED);
        IntentFilter filter2     = new IntentFilter(NfcAdapter.ACTION_NDEF_DISCOVERED);
        readTagFilters = new IntentFilter[]{tagDetected,filter2};


        btn_back = (Button) findViewById(R.id.btn_back);

        btn_back.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                Intent i = new Intent(getApplicationContext(),NFCTagWriterActivity.class);
                i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                startActivity(i);

            }
        });
    }

    @Override
    protected void onNewIntent(Intent intent) {
        // TODO Auto-generated method stub

        setIntent(intent); 
        if(getIntent().getAction().equals(NfcAdapter.ACTION_TAG_DISCOVERED)){
            detectedTag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);

            readFromTag(getIntent());
        }

        else{
            AlertDialog.Builder builder = new AlertDialog.Builder(getApplicationContext());
            builder.setMessage("Tag Not Detected! Please Bring Tag In Proximity").setCancelable(false).setPositiveButton("OK", new DialogInterface.OnClickListener() {

                @Override
                public void onClick(DialogInterface dialog, int which) {
                    // TODO Auto-generated method stub

                }
            }).show();

            AlertDialog alert = builder.create();
            Toast.makeText(getApplicationContext(), "No Tag Detected", Toast.LENGTH_LONG).show();
        }

    }


    @Override
    protected void onResume() {
        // TODO Auto-generated method stub
        super.onResume();
        nfcAdapter.enableForegroundDispatch(this, pendingIntent, readTagFilters, null);
    }


    public void readFromTag(Intent intent){

        Ndef ndef = Ndef.get(detectedTag);


        try{
            ndef.connect();

            txtType.setText(ndef.getType().toString());
            txtSize.setText(String.valueOf(ndef.getMaxSize()));

            Parcelable[] messages = intent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);

            if (messages != null) {
                NdefMessage[] ndefMessages = new NdefMessage[messages.length];
                for (int i = 0; i < messages.length; i++) {
                    ndefMessages[i] = (NdefMessage) messages[i];
                }
            NdefRecord record = ndefMessages[0].getRecords()[0];

            byte[] payload = record.getPayload();
            int length = payload.length;

            new_payload = new byte[length-3];
            System.arraycopy(payload, 3, new_payload, 0,length-3);

            String text = new String(new_payload);

            txtRead.setText(text);
            Toast.makeText(getApplicationContext(), text, Toast.LENGTH_LONG).show();

            if(text.equalsIgnoreCase("silent")){
                Toast.makeText(getApplicationContext(), text, Toast.LENGTH_LONG).show();
                AudioManager audiomanage = (AudioManager)getSystemService(Context.AUDIO_SERVICE);  
                audiomanage.setRingerMode(AudioManager.RINGER_MODE_SILENT); 
            }
            if(text.equalsIgnoreCase("vibrate")){
                AudioManager audiomanage = (AudioManager)getSystemService(Context.AUDIO_SERVICE);  
                audiomanage.setRingerMode(AudioManager.RINGER_MODE_VIBRATE); 
            }
            if(text.equalsIgnoreCase("normal")){
                AudioManager audiomanage = (AudioManager)getSystemService(Context.AUDIO_SERVICE);  
                audiomanage.setRingerMode(AudioManager.RINGER_MODE_NORMAL); 
            }

            ndef.close();

        }
        }
        catch (Exception e) {
            Toast.makeText(getApplicationContext(),e.toString(), Toast.LENGTH_LONG).show();
        }
    }   
}
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1 回答 1

1

问题是，onNewIntent 没有在 onCreate 方法中调用。想到的快速解决方案是：

在 onCreate 方法中，您可以检查意图类型。如果它是一个标签被发现，你处理它就像在 onNewIntent 中一样。

另一种解决方案是将处理代码放在 onResume 中（如果标记 reding 是您的应用程序所做的全部）并在那里检查意图。

也许有更清洁的解决方案，稍后再考虑一下，但是现在，这应该对您有所帮助。

于 2012-09-24T11:14:57.420 回答