NDEF发现/活动启动后如何显示NDEF消息？

Question

我已经通读了许多和我的问题类似的问题--如果我没有找到解决问题的办法，我只能道歉，但我真的解决不了这个问题！

我已经设法让我的nfc活动正常工作了--点击标签就会启动我的应用程序的正确活动--但是ndef消息没有显示，我不知道为什么……

该标记是Mifare Ultralight，其中包含编码的纯文本消息。(mimetype:纯/文本)

这是我的代码，感谢大家的帮助，这个论坛应该有一个‘捐赠啤酒’按钮！

package com.example.prototype02;

import android.app.Activity;
import android.app.AlertDialog;
import android.app.PendingIntent;
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.widget.Toast;

public class nfcActivity 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.nfclayout);

        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 nfcIntent = new IntentFilter(NfcAdapter.ACTION_NDEF_DISCOVERED);
        nfcIntent.addDataScheme("text/plain");      
        mNdefExchangeFilters = new IntentFilter[] { nfcIntent };

    }

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

    @Override
    protected void onNewIntent(Intent intent) {
        super.onNewIntent(intent);      
        if (mNfcAdapter.ACTION_NDEF_DISCOVERED.equals(intent.getAction())) {
            NdefMessage[] messages = null;
            Parcelable[] rawMsgs = intent.getParcelableArrayExtra(mNfcAdapter.EXTRA_NDEF_MESSAGES);
            if (rawMsgs != null) {
                messages = new NdefMessage[rawMsgs.length];
                for (int i = 0; i < rawMsgs.length; i++) {
                    messages[i] = (NdefMessage) rawMsgs[i];
                }}
                else if (rawMsgs == null){
                    Toast.makeText(getApplicationContext(), "No NDEF Message Read", Toast.LENGTH_LONG).show();
                }
            if(messages[0] != null) {
                String result="";
                byte[] payload = messages[0].getRecords()[0].getPayload();
                for (int b = 1; b<payload.length; b++) { // skip SOH
                    result += (char) payload[b];
                }
                Toast.makeText(getApplicationContext(), "Safe Location Registered - " + result, Toast.LENGTH_SHORT).show();
            }
        }
        else Toast.makeText(getApplicationContext(), "Intent Error...", Toast.LENGTH_LONG).show();

        }
    }

Answer 1

如果您的活动是由NFC意图启动的，则不会调用onNewIntent() (只有在活动已经在前台时扫描标记时才会调用它)。尝试执行一些操作，比如在onCreate()中调用onNewIntent(getIntent())。

Answer 2

尝试如下所示：(摘自StickyNotes NFC示例)

@Override
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();
        setNoteBody(new String(payload));
        setIntent(new Intent()); // Consume this intent.
    }
    enableNdefExchangeMode();
}

@Override
protected void onPause() {
    super.onPause();
    mResumed = false;
    mNfcAdapter.disableForegroundNdefPush(this);
}

@Override
protected void onNewIntent(Intent intent) {
    // NDEF exchange mode
    if (!mWriteMode && NfcAdapter.ACTION_NDEF_DISCOVERED.equals(intent.getAction())) {
        NdefMessage[] msgs = getNdefMessages(intent);
        promptForContent(msgs[0]);
    }

    // Tag writing mode
    if (mWriteMode && NfcAdapter.ACTION_TAG_DISCOVERED.equals(intent.getAction())) {
        Tag detectedTag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
        writeTag(getNoteAsNdef(), detectedTag);
    }
}