2
我有一个应用程序，似乎工作正常，可以通过NFC完美地传输数据。我有一项主要活动，一项传输数据的活动以及一项接收数据的不同活动。在NFC接收时保持当前活动
发件人活动效果很好，但是当接收者获得NFC意图时，它会将应用程序重新启动回主要活动。
我不完全确定这是为什么。除非用户已经在该活动中，并且如果他们是，继续参与该活动并处理NFC意图，否则我希望它会拒绝任何推送。
这里是清单：
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".Timer" />
<activity android:name=".AddSlaves"
android:label="Add Slave Devices"
android:launchMode="singleTask">
<intent-filter>
<action android:name="android.nfc.action.NDEF_DISCOVERED" />
<category android:name="android.intent.category.DEFAULT" />
<data android:mimeType="text/plain" />
</intent-filter>
</activity>
<activity android:name=".JoinSrv"
android:launchMode="singleTask">
<intent-filter>
<action android:name="android.nfc.action.NDEF_DISCOVERED" />
<category android:name="android.intent.category.DEFAULT"/>
<data android:mimeType="text/plain" />
</intent-filter>
</activity>
这里是发件人类：
public class JoinSrv extends Activity implements NfcAdapter.OnNdefPushCompleteCallback, NfcAdapter.CreateNdefMessageCallback {
//The array lists to hold our messages
private ArrayList<String> messagesToSendArray = new ArrayList<>();
private ArrayList<String> messagesReceivedArray = new ArrayList<>();
//Text boxes to add and display our messages
private NfcAdapter mNfcAdapter;
//Save our Array Lists of Messages for if the user navigates away
@Override
public void onSaveInstanceState(@NonNull Bundle savedInstanceState) {
super.onSaveInstanceState(savedInstanceState);
savedInstanceState.putStringArrayList("messagesToSend", messagesToSendArray);
savedInstanceState.putStringArrayList("lastMessagesReceived", messagesReceivedArray);
}
//Load our Array Lists of Messages for when the user navigates back
@Override
public void onRestoreInstanceState(@NonNull Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
messagesToSendArray = savedInstanceState.getStringArrayList("messagesToSend");
messagesReceivedArray = savedInstanceState.getStringArrayList("lastMessagesReceived");
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_join_srv);
//Check if NFC is available on device
mNfcAdapter = NfcAdapter.getDefaultAdapter(this);
if (mNfcAdapter != null) {
//Handle some NFC initialization here
} else {
Toast.makeText(this, "NFC not available on this device",
Toast.LENGTH_SHORT).show();
}
//Check if NFC is available on device
mNfcAdapter = NfcAdapter.getDefaultAdapter(this);
if (mNfcAdapter != null) {
//This will refer back to createNdefMessage for what it will send
mNfcAdapter.setNdefPushMessageCallback(this, this);
//This will be called if the message is sent successfully
mNfcAdapter.setOnNdefPushCompleteCallback(this, this);
}
}
@Override
public NdefMessage createNdefMessage(NfcEvent event) {
//This will be called when another NFC capable device is detected.
//We'll write the createRecords() method in just a moment
NdefRecord[] recordsToAttach = createRecords();
//When creating an NdefMessage we need to provide an NdefRecord[]
return new NdefMessage(recordsToAttach);
}
@Override
public void onNdefPushComplete(NfcEvent event) {
//This is called when the system detects that our NdefMessage was
//Successfully sent.
messagesToSendArray.clear();
}
public NdefRecord[] createRecords() {
NdefRecord[] records = new NdefRecord[1];
//To Create Messages Manually if API is less than
if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN) {
byte[] payload = "192.168.1.100".
getBytes(Charset.forName("UTF-8"));
NdefRecord record = new NdefRecord(
NdefRecord.TNF_WELL_KNOWN, //Our 3-bit Type name format
NdefRecord.RTD_TEXT, //Description of our payload
new byte[0], //The optional id for our Record
payload); //Our payload for the Record
records[1] = record;
}
//Api is high enough that we can use createMime, which is preferred.
else {
byte[] payload = "192.168.1.100".
getBytes(Charset.forName("UTF-8"));
NdefRecord record = NdefRecord.createMime("text/plain",payload);
records[1] = record;
}
records[messagesToSendArray.size()] =
NdefRecord.createApplicationRecord(getPackageName());
return records;
}
private void handleNfcIntent(Intent NfcIntent) {
if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(NfcIntent.getAction())) {
Parcelable[] receivedArray =
NfcIntent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);
if (receivedArray != null) {
messagesReceivedArray.clear();
NdefMessage receivedMessage = (NdefMessage) receivedArray[0];
NdefRecord[] attachedRecords = receivedMessage.getRecords();
for (NdefRecord record : attachedRecords) {
String string = new String(record.getPayload());
//Make sure we don't pass along our AAR (Android Application Record)
if (string.equals(getPackageName())) {
continue;
}
messagesReceivedArray.add(string);
}
Toast.makeText(this, "Received " + messagesReceivedArray.size() +
" Messages", Toast.LENGTH_LONG).show();
} else {
Toast.makeText(this, "Received Blank Parcel", Toast.LENGTH_LONG).show();
}
}
}
@Override
public void onNewIntent(Intent intent) {
handleNfcIntent(intent);
}
@Override
public void onResume() {
super.onResume();
handleNfcIntent(getIntent());
}
}
这里是接收机类：
public class AddSlaves extends Activity implements NfcAdapter.OnNdefPushCompleteCallback, NfcAdapter.CreateNdefMessageCallback{
//The array lists to hold our messages
private ArrayList<String> messagesToSendArray = new ArrayList<>();
private ArrayList<String> messagesReceivedArray = new ArrayList<>();
//Text boxes to add and display our messages
private EditText txtBoxAddMessage;
private TextView txtReceivedMessages;
private TextView txtMessagesToSend;
private NfcAdapter mNfcAdapter;
private void updateTextViews() {
txtReceivedMessages.setText("Messages Received:\n");
//Populate our list of messages we have received
if (messagesReceivedArray.size() > 0) {
for (int i = 0; i < messagesReceivedArray.size(); i++) {
txtReceivedMessages.append(messagesReceivedArray.get(i));
txtReceivedMessages.append("\n");
}
}
}
//Save our Array Lists of Messages for if the user navigates away
@Override
public void onSaveInstanceState(@NonNull Bundle savedInstanceState) {
super.onSaveInstanceState(savedInstanceState);
savedInstanceState.putStringArrayList("lastMessagesReceived",messagesReceivedArray);
}
//Load our Array Lists of Messages for when the user navigates back
@Override
public void onRestoreInstanceState(@NonNull Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
messagesReceivedArray = savedInstanceState.getStringArrayList("lastMessagesReceived");
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_add_slaves);
txtReceivedMessages = (TextView) findViewById(R.id.txtMessagesReceived);
Button btnAddMessage = (Button) findViewById(R.id.buttonAddMessage);
//Check if NFC is available on device
mNfcAdapter = NfcAdapter.getDefaultAdapter(this);
if(mNfcAdapter != null) {
//Handle some NFC initialization here
}
else {
Toast.makeText(this, "NFC not available on this device",
Toast.LENGTH_SHORT).show();
}
//Check if NFC is available on device
mNfcAdapter = NfcAdapter.getDefaultAdapter(this);
if(mNfcAdapter != null) {
//This will refer back to createNdefMessage for what it will send
mNfcAdapter.setNdefPushMessageCallback(this, this);
//This will be called if the message is sent successfully
mNfcAdapter.setOnNdefPushCompleteCallback(this, this);
}
}
@Override
public NdefMessage createNdefMessage(NfcEvent event) {
//This will be called when another NFC capable device is detected.
return null;
}
@Override
public void onNdefPushComplete(NfcEvent event) {
//This is called when the system detects that our NdefMessage was
//Successfully sent.
messagesToSendArray.clear();
}
private void handleNfcIntent(Intent NfcIntent) {
if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(NfcIntent.getAction())) {
Parcelable[] receivedArray =
NfcIntent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);
if(receivedArray != null) {
messagesReceivedArray.clear();
NdefMessage receivedMessage = (NdefMessage) receivedArray[0];
NdefRecord[] attachedRecords = receivedMessage.getRecords();
for (NdefRecord record:attachedRecords) {
String string = new String(record.getPayload());
//Make sure we don't pass along our AAR (Android Application Record)
if (string.equals(getPackageName())) { continue; }
messagesReceivedArray.add(string);
}
Toast.makeText(this, "Received " + messagesReceivedArray.size() +
" Messages", Toast.LENGTH_LONG).show();
updateTextViews();
}
else {
Toast.makeText(this, "Received Blank Parcel", Toast.LENGTH_LONG).show();
}
}
}
@Override
public void onNewIntent(Intent intent) {
handleNfcIntent(intent);
}
@Override
public void onResume() {
super.onResume();
updateTextViews();
handleNfcIntent(getIntent());
}
}
我猜你的问题是由于'singleTask'启动模式。你为什么指定？请解释您的应用程序导航。 –
此外，您还有2项活动可以处理'NDEF_DISCOVERED'动作。这意味着Android在扫描NFC标签时不知道要开始哪一个。你如何处理这个问题？ –