Android 简单 NFC 阅读器应用程序源代码错误。它不会读取任何 nfc 标签？

Question

我有这个源代码，它应该读取一个 NDEF nfc 标签。除了扫描标签时，它不会做任何事情。有什么想法吗？

代码编译，没有错误。

看起来不像函数 protected void onNewIntent(Intent intent) 已运行。

package com.tapwise.nfcreadtag;

import android.app.Activity;
import android.app.AlertDialog;
import android.app.PendingIntent;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.IntentFilter;
import android.nfc.NdefMessage;
import android.nfc.NfcAdapter;
import android.os.Bundle;
import android.os.Parcelable;
import android.os.PatternMatcher;
import android.provider.Settings;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Toast;

    public class MainActivity extends Activity {
    private static final String TAG = "NFCReadTag";
    private NfcAdapter mNfcAdapter;
    private IntentFilter[] mNdefExchangeFilters;
    private PendingIntent mNfcPendingIntent;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

    mNfcAdapter = NfcAdapter.getDefaultAdapter(this);

    mNfcPendingIntent = PendingIntent.getActivity(this, 0, new Intent(this,
                getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP
                | Intent.FLAG_ACTIVITY_CLEAR_TOP), 0);


    IntentFilter smartwhere = new IntentFilter (NfcAdapter.ACTION_NDEF_DISCOVERED);
        smartwhere.addDataScheme("http");
        smartwhere.addDataAuthority("www.smartwhere.com", null);
        smartwhere.addDataPath(".*", PatternMatcher.PATTERN_SIMPLE_GLOB);

        mNdefExchangeFilters = new IntentFilter[] { smartwhere };

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }

    @Override
    protected void onResume() {
        super.onResume();
        if(mNfcAdapter != null) {
            mNfcAdapter.enableForegroundDispatch(this, mNfcPendingIntent,
                mNdefExchangeFilters, null);
            if (!mNfcAdapter.isEnabled()){

                LayoutInflater inflater = getLayoutInflater();
                View dialoglayout = inflater.inflate(R.layout.nfc_settings_layout,(ViewGroup) findViewById(R.id.nfc_settings_layout));
                new AlertDialog.Builder(this).setView(dialoglayout)
                        .setPositiveButton("Update Settings", new DialogInterface.OnClickListener() {
                            public void onClick(DialogInterface arg0, int arg1) {
                                Intent setnfc = new Intent(Settings.ACTION_WIRELESS_SETTINGS);
                                startActivity(setnfc);
                            }
                        })
                        .setOnCancelListener(new DialogInterface.OnCancelListener() {

                            public void onCancel(DialogInterface dialog) {
                                finish(); // exit application if user cancels
                            }                           
                        }).create().show();

            }
        } else {
            Toast.makeText(getApplicationContext(), "Sorry, No NFC Adapter found.", Toast.LENGTH_SHORT).show();
        }


    }

    @Override
    protected void onPause() {
        super.onPause();
        if(mNfcAdapter != null) mNfcAdapter.disableForegroundDispatch(this);
    }

    @Override
    protected void onNewIntent(Intent intent) {
        super.onNewIntent(intent);      
        if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(intent.getAction())) {
            NdefMessage[] messages = null;
            Parcelable[] rawMsgs = intent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);
            if (rawMsgs != null) {
                messages = new NdefMessage[rawMsgs.length];
                for (int i = 0; i < rawMsgs.length; i++) {
                    messages[i] = (NdefMessage) rawMsgs[i];
                }
            }
            if(messages[0] != null) {
                String result="";
                byte[] payload = messages[0].getRecords()[0].getPayload();
                // this assumes that we get back am SOH followed by host/code
                for (int b = 1; b<payload.length; b++) { // skip SOH
                    result += (char) payload[b];
                }
                Toast.makeText(getApplicationContext(), "Tag Contains " + result, Toast.LENGTH_SHORT).show();
            }
        }
    }
}

Answer 1

如果您使用的是 Nexus 4，则设备无法读取 MIFARE 经典标签。