NFC 書き込みサンプル

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【Android】 NFC を試しました

で使ってる NFC 書き込みサンプルの Gist

書籍『NFC Hacks』（株式会社ブリリアントサービス著, オライリージャパン発行）の Hack #35 を参考にして作成

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <EditText
        android:id="@+id/id_editText"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:hint="enter id"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        android:autofillHints="no"
        android:inputType="number" />

    <EditText
        android:id="@+id/note_editText"
        android:layout_width="match_parent"
        android:layout_height="45dp"
        android:hint="Hello World!"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/id_editText"
        android:autofillHints="no"
        android:inputType="text" />

    <Button
        android:id="@+id/writeButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/note_editText" />


</androidx.constraintlayout.widget.ConstraintLayout>

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.nfcwriterexample">

    <uses-permission android:name="android.permission.NFC" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity
            android:name=".MainActivity"
            android:launchMode="singleTask">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
<!--
            <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>
    </application>

</manifest>

MainActivity.java

package com.example.nfcwriterexample;

import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;

import android.app.PendingIntent;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.IntentFilter;
import android.nfc.FormatException;
import android.nfc.NdefMessage;
import android.nfc.NdefRecord;
import android.nfc.NfcAdapter;
import android.nfc.Tag;
import android.nfc.tech.Ndef;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import java.io.IOException;

/**
 * 書籍 『NFC Hacks』 （株式会社ブリリアントサービス著, オライリージャパン発行）の Hack #35 を参考に作成した
 * NFC書き込みアプリのサンプル実装
 */
public class MainActivity extends AppCompatActivity {

    private static final String TAG = MainActivity.class.getSimpleName();

    private NfcAdapter mNfcAdapter;
    private EditText mId;
    private EditText mText;
    private IntentFilter[] mNdefFilters;
    private boolean mWriteFlag;
    private PendingIntent mPendingIntent;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.d(TAG, "onCreate");

        setContentView(R.layout.activity_main);

        mNfcAdapter = NfcAdapter.getDefaultAdapter(this);
        mId = (EditText) findViewById(R.id.id_editText);
        mText = (EditText) findViewById(R.id.note_editText);
        Button mButton = (Button) findViewById(R.id.writeButton);

        mButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Log.d(TAG, "Button#onClick");
                IntentFilter filter = new IntentFilter(NfcAdapter.ACTION_TAG_DISCOVERED);
                mNdefFilters = new IntentFilter[] {filter};
                enableNdefMode(mNdefFilters);

                new AlertDialog.Builder(MainActivity.this).setTitle("書き込みモード")
                        .setOnCancelListener(new DialogInterface.OnCancelListener() {
                            @Override
                            public void onCancel(DialogInterface dialogInterface) {
                                disableNdefMode();
                            }
                        }).create().show();
            }
        });

        mPendingIntent = PendingIntent.getActivity(this, 0, new Intent(this, getClass()), 0);
    }

    private void disableNdefMode() {
        Log.d(TAG, "disableNdefMode");

        mNfcAdapter.disableForegroundDispatch(this);
        mWriteFlag = false;
    }
    private void enableNdefMode(IntentFilter[] filters) {
        Log.d(TAG, "enableNdefMode");

        mNfcAdapter.enableForegroundDispatch(this, mPendingIntent, filters, null);
        mWriteFlag = true;
    }

    @Override
    protected void onNewIntent(Intent intent) {
        super.onNewIntent(intent);
        Log.d(TAG, "onNewIntent");

        if (mWriteFlag && (intent.getAction().equals(NfcAdapter.ACTION_NDEF_DISCOVERED) || intent.getAction().equals(NfcAdapter.ACTION_TAG_DISCOVERED))) {
            writeNdef(intent);
            Toast.makeText(this, "NDEF への書き込みが完了しました", Toast.LENGTH_LONG).show();
        }
    }

    private void writeNdef(Intent intent) {
        Ndef ndef = null;
        Tag tag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
        NdefMessage msg = createNdefMessage();
        ndef = Ndef.get(tag);
        if (ndef != null) {
            try {
                ndef.connect();
                ndef.writeNdefMessage(msg);
                ndef.close();
            } catch (FormatException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    private NdefMessage createNdefMessage() {
        byte[] textBytes = mText.getText().toString().getBytes();
        byte[] idBytes = mId.getText().toString().getBytes();
        //NdefRecord record = new NdefRecord(NdefRecord.TNF_MIME_MEDIA, "text/plain;charset=utf-8".getBytes(), idBytes, textBytes);
        //NdefRecord record = NdefRecord.createMime("text/plain;charset=utf-8", textBytes);
        //NdefRecord record = new NdefRecord(NdefRecord.TNF_UNKNOWN, null, idBytes, textBytes);
        NdefRecord record = new NdefRecord(NdefRecord.TNF_MIME_MEDIA, "text/plain".getBytes(), idBytes, textBytes);
        return new NdefMessage(new NdefRecord[] {record});
    }
}