我希望我的 ActivityNFCSender 通过 NFC 向我的 ActivityNFCReceiver 发送一个整数。下面的代码有效。但是有一个问题：建立连接后，两个活动都显示发送提示！但我只希望第一个能够发送（整数）并显示提示。怎么做？
活动NFCSender：
public class ActivityNFCSender extends ActivityBase {
public static final String EXTRA_RES_ID = "res_id";
private NfcAdapter mNfcAdapter;
private int mReservServerId;
@Override
public void onCreate(Bundle savedInstanceState) {
setContentView(R.layout.activity_nfc);
super.onCreate(savedInstanceState);
mReservServerId = getIntent().getIntExtra(EXTRA_RES_ID, 0);
}
public void onResume(){
super.onResume();
mNfcAdapter = NfcAdapter.getDefaultAdapter(this);
if(mNfcAdapter == null){
messageDialogQuit(R.string.error_no_nfc);
}
else if(!mNfcAdapter.isEnabled()){
new AlertDialog.Builder(this).setCancelable(true).setMessage(R.string.error_nfc_off)
.setPositiveButton(R.string.turn_on, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
dialog.dismiss();
Intent settingsIntent = new Intent(Settings.ACTION_SETTINGS);
startActivity(settingsIntent);
}
})
.setNegativeButton(R.string.cancel, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
dialog.dismiss();
finish();
}
})
.create().show();
}
else{
//Set sending
mNfcAdapter.enableForegroundNdefPush(ActivityNFCSender.this, getIntAsNdef(mReservServerId));
}
}
public void onPause(){
if(mNfcAdapter != null && mNfcAdapter.isEnabled()){
mNfcAdapter.disableForegroundNdefPush(this);
}
super.onPause();
}
private NdefMessage getIntAsNdef(int pInt) {
byte[] textBytes = (pInt+"").getBytes(Charset.forName("UTF8"));
NdefRecord textRecord = new NdefRecord(NdefRecord.TNF_MIME_MEDIA, "text/plain".getBytes(), new byte[] {}, textBytes);
return new NdefMessage(new NdefRecord[] {
textRecord
});
}
活动NFC接收器：
public class ActivityNFCReceiver extends ActivityBase {
private NfcAdapter mNfcAdapter;
private PendingIntent mNfcPendingIntent;
private IntentFilter[] mNdefExchangeFilters;
@Override
public void onCreate(Bundle savedInstanceState) {
setContentView(R.layout.activity_nfc);
super.onCreate(savedInstanceState);
((TextView) findViewById(R.id.nfcTVStatus)).setText(R.string.receiving);
}
public void onResume(){
super.onResume();
mNfcAdapter = NfcAdapter.getDefaultAdapter(this);
if(mNfcAdapter == null){
messageDialogQuit(R.string.error_no_nfc);
}
else if(!mNfcAdapter.isEnabled()){
new AlertDialog.Builder(this).setCancelable(true).setMessage(R.string.error_nfc_off)
.setPositiveButton(R.string.turn_on, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
dialog.dismiss();
Intent settingsIntent = new Intent(Settings.ACTION_SETTINGS);
startActivity(settingsIntent);
}
})
.setNegativeButton(R.string.cancel, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
dialog.dismiss();
finish();
}
})
.create().show();
}
else{
mNfcPendingIntent = PendingIntent.getActivity(this, 0, new Intent(this, getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);
// Intent filters for exchanging over p2p.
IntentFilter ndefDetected = new IntentFilter(NfcAdapter.ACTION_NDEF_DISCOVERED);
try {
ndefDetected.addDataType("text/plain");
}
catch (MalformedMimeTypeException e) {
e.printStackTrace();
}
mNdefExchangeFilters = new IntentFilter[] { ndefDetected };
//set receiving
mNfcAdapter.enableForegroundDispatch(ActivityNFCReceiver.this, mNfcPendingIntent, mNdefExchangeFilters, null);
}
}
public void onPause(){
if(mNfcAdapter != null && mNfcAdapter.isEnabled()){
mNfcAdapter.disableForegroundDispatch(ActivityNFCReceiver.this);
}
super.onPause();
}
@Override
protected void onNewIntent(Intent intent) {
if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(intent.getAction())) {
NdefMessage[] msgs = getNdefMessages(intent);
if(msgs.length > 0){
try{
NdefRecord firstRecord = msgs[0].getRecords()[0];
byte[] payload = firstRecord.getPayload();
String str = new String(payload, Charset.forName("UTF8"));
int reservServerId = Integer.parseInt(str);
returnResult(reservServerId);
}
catch(Exception e){
messageDialog(R.string.error_during_NFC);
}
}
}
}
public void onCancelClicked(View pV){
finish();
}
private NdefMessage[] getNdefMessages(Intent intent) {
// Parse the intent
NdefMessage[] msgs = null;
String action = intent.getAction();
if (NfcAdapter.ACTION_TAG_DISCOVERED.equals(action) || NfcAdapter.ACTION_NDEF_DISCOVERED.equals(action)) {
Parcelable[] rawMsgs = intent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);
if (rawMsgs != null) {
msgs = new NdefMessage[rawMsgs.length];
for (int i = 0; i < rawMsgs.length; i++) {
msgs[i] = (NdefMessage) rawMsgs[i];
}
}
else {
// Unknown tag type
byte[] empty = new byte[] {};
NdefRecord record = new NdefRecord(NdefRecord.TNF_UNKNOWN, empty, empty, empty);
NdefMessage msg = new NdefMessage(new NdefRecord[] { record });
msgs = new NdefMessage[] { msg };
}
}
else {
Log.d(TAG, "Unknown intent.");
finish();
}
return msgs;
}
private void returnResult(int pResServerId){
Intent result = new Intent();
result.putExtra(ActivityCompanySubMenu.EXTRA_RES_SERVER_ID, pResServerId);
setResult(RESULT_OK, result);
finish();
}
}