java - 待定 Intent 总是进行新 Activity

Question

我正在尝试制作具有 nfc 功能的应用程序。问题是当发现 nfc 标签时，挂起的 Intent 总是会产生一个已经存在的新 Activity 。我正在使用标签主机。如何在不进行新 Activity 的情况下进行 pendingintent。非常感谢。

 public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.main);        

            mNfcAdapter = NfcAdapter.getDefaultAdapter(this);                              
            mNfcPendingIntent = PendingIntent.getActivity(this, 0,new Intent(this,
    getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);
    }

    protected void onResume() {    
            super.onResume();
            mResumed = true;               
            // Sticky notes received from Android
            if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(getIntent().getAction())) {            
                NdefMessage[] messages = getNdefMessages(getIntent());
                byte[] payload = messages[0].getRecords()[0].getPayload();            
                try     { cekNfc(new String(payload)); }
                catch (SQLException e)          { e.printStackTrace(); } 
                catch (NoSuchAlgorithmException e)      {  e.printStackTrace(); }
                catch (UnsupportedEncodingException e)  { e.printStackTrace(); }

                setIntent(new Intent());
            }
            enableNdefExchangeMode();        
        }   
        private void enableNdefExchangeMode() { mNfcAdapter.enableForegroundDispatch(this, mNfcPendingIntent, mNdefExchangeFilters, null); } 

    NdefMessage[] getNdefMessages(Intent intent) {  // Parse the intent             
            NdefMessage[] msgs = null;        
            String action = intent.getAction();
            //jika ada action
            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]; }
                }
            } 
            return msgs;
        }


 public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.main);        

            mNfcAdapter = NfcAdapter.getDefaultAdapter(this);                              
            mNfcPendingIntent = PendingIntent.getActivity(this, 0,new Intent(this,
    getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);
    }

    protected void onResume() {    
            super.onResume();
            mResumed = true;               
            // Sticky notes received from Android
            if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(getIntent().getAction())) {            
                NdefMessage[] messages = getNdefMessages(getIntent());
                byte[] payload = messages[0].getRecords()[0].getPayload();            
                try     { cekNfc(new String(payload)); }
                catch (SQLException e)          { e.printStackTrace(); } 
                catch (NoSuchAlgorithmException e)      {  e.printStackTrace(); }
                catch (UnsupportedEncodingException e)  { e.printStackTrace(); }

                setIntent(new Intent());
            }
            enableNdefExchangeMode();        
        }   
        private void enableNdefExchangeMode() { mNfcAdapter.enableForegroundDispatch(this, mNfcPendingIntent, mNdefExchangeFilters, null); } 

    NdefMessage[] getNdefMessages(Intent intent) {  // Parse the intent             
            NdefMessage[] msgs = null;        
            String action = intent.getAction();
            //jika ada action
            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]; }
                }
            } 
            return msgs;
        }

Answer 1

将 android:launchMode="singleTask" 用于 list 中的 Activity (或多个 Activity )。这样就可以了。每当系统发送 NFC intent 时，总会创建一个新的 Activity。这对于 NFC Intent 是独一无二的。因此设置 android:launchMode="singleTop" 将不起作用，也不会在 PendingIntent 中设置标志。

另一个解决方案是使用 NfcAdapter.enableForegroundDispatch()在你所有的 Activity 中。这样您的应用就可以直接处理所有 NFC Intent (通过 onNewIntent())。