10、NFC技术：读写NFC标签中的文本数据

代码实现过程如下：

读写NFC标签的纯文本数据.java

 import java.nio.charset.Charset;
import java.util.Locale;

import android.app.Activity;
import android.content.Intent;
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.view.View;
import android.widget.TextView;

/**
 * 主 Activity
 * 读写NFC标签的纯文本数据
 * @author dr
 * 
 */
public class ReadWriteTextMainActivity extends Activity {
    private TextView mInputText;
    private String mText;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_read_write_text_main);

        mInputText = (TextView) findViewById(R.id.textview_input_text);
    }

    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == 1 && resultCode == 1) {
            mText = data.getStringExtra("text");
            mInputText.setText(mText);
        }
    }

    public void onNewIntent(Intent intent) {
        // read nfc text
        if (mText == null) {
            // 显示NFC标签内容
            Intent myIntent = new Intent(this, ShowNFCTagContentActivity.class);
            myIntent.putExtras(intent);
            myIntent.setAction(NfcAdapter.ACTION_NDEF_DISCOVERED);
            startActivity(myIntent);

        } else {  // write nfc text
            Tag tag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
            NdefMessage ndefMessage = new NdefMessage(
                    new NdefRecord[] { createTextRecord(mText) });
            writeTag(ndefMessage, tag);
        }
    }
    
    /**
     * 将纯文本转换成NdefRecord对象。
     * @param text
     * @return
     */
    public NdefRecord createTextRecord(String text) {
        // 得到生成语言编码字节数组
        byte[] langBytes = Locale.CHINA.getLanguage().getBytes(
                Charset.forName("US-ASCII"));
        Charset utfEncoding = Charset.forName("UTF-8");
        byte[] textBytes = text.getBytes(utfEncoding);
        int utfBit = 0;
        // 状态字节
        char status = (char) (utfBit + langBytes.length);

        byte[] data = new byte[1 + langBytes.length + textBytes.length];
        data[0] = (byte) status;
        // 数组拷贝
        System.arraycopy(langBytes, 0, data, 1, langBytes.length);
        System.arraycopy(textBytes, 0, data, 1 + langBytes.length,
                textBytes.length);

        NdefRecord ndefRecord = new NdefRecord(NdefRecord.TNF_WELL_KNOWN,
                NdefRecord.RTD_TEXT, new byte[0], data);
        return ndefRecord;
    }

    boolean writeTag(NdefMessage ndefMessage, Tag tag) {
        try {
            Ndef ndef = Ndef.get(tag);
            ndef.connect();
            ndef.writeNdefMessage(ndefMessage);
            return true;
        } catch (Exception e) {
            // TODO: handle exception
        }
        return false;
    }

    // 向NFC标签写入文本
    public void onClick_InputText(View view) {
        Intent intent = new Intent(this, InputTextActivity.class);
        startActivityForResult(intent, 1);
    }

}

读写NFC标签的纯文本数据.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="onClick_InputText"
        android:text="输入要写入文本" />

    <TextView
        android:id="@+id/textview_input_text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="16sp" />

    <TextView

        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="30dp"
        android:text="请将NFC标签靠近手机背面读取或写入文本"
        android:textColor="#F00"
        android:textSize="16sp" />

    <ImageView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:src="@drawable/read_nfc_tag" />

</LinearLayout>

显示NFC标签内容.java

import cn.eoe.read.write.text.library.TextRecord;
import android.app.Activity;
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.os.Parcelable;
import android.widget.TextView;


/**
 * 显示NFC标签内容
 * @author dr
 *
 */
public class ShowNFCTagContentActivity extends Activity {

    private TextView mTagContent;
    private Tag mDetectedTag;   // 传递过来的NFC的一个TAG对象
    private String mTagText;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_show_nfctag_content);
        mTagContent = (TextView) findViewById(R.id.textview_tag_content);

        mDetectedTag = getIntent().getParcelableExtra(NfcAdapter.EXTRA_TAG);

        Ndef ndef = Ndef.get(mDetectedTag);

        mTagText = ndef.getType() + "
max size:" + ndef.getMaxSize()
                + "bytes

";

        readNFCTag();

        mTagContent.setText(mTagText);
    }

    /**
     * 
     */
    private void readNFCTag() {
        if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(getIntent().getAction())) {
            Parcelable[] rawMsgs = getIntent().getParcelableArrayExtra(
                    NfcAdapter.EXTRA_NDEF_MESSAGES);
            NdefMessage msgs[] = null;
            int contentSize = 0;
            if (rawMsgs != null) {
                msgs = new NdefMessage[rawMsgs.length];
                for (int i = 0; i < rawMsgs.length; i++) {
                    msgs[i] = (NdefMessage) rawMsgs[i];
                    contentSize += msgs[i].toByteArray().length;
                }
            }
            try {
                if (msgs != null) {
                    NdefRecord record = msgs[0].getRecords()[0];
                    TextRecord textRecord = TextRecord.parse(record);
                    mTagText += textRecord.getText() + "

text
"
                            + contentSize + " bytes";
                }
            } catch (Exception e) {
                // TODO: handle exception
            }
        }
    }
}

显示NFC标签内容.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/textview_tag_content"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="16sp" android:layout_margin="6dp" />

</LinearLayout>

向NFC标签写入文本.java

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;

/**
 * 向NFC标签写入文本
 * 
 * @author dr
 * 
 */
public class InputTextActivity extends Activity {

    private EditText mTextTag;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_input_text);
        mTextTag = (EditText) findViewById(R.id.edittext_text_tag);
    }

    public void onClick_OK(View view) {
        Intent intent = new Intent();
        intent.putExtra("text", mTextTag.getText().toString());
        setResult(1, intent);
        finish();

    }
}

向NFC标签写入文本.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        
        android:text="请输入要写入的文本" android:textSize="16sp" />

    <EditText
        android:layout_marginTop="10dp"
        android:id="@+id/edittext_text_tag"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"    
        android:onClick="onClick_OK"
        android:text="确定" />

</LinearLayout>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="cn.eoe.read.write.text"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="15"
        android:targetSdkVersion="15" />

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

    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".ReadWriteTextMainActivity"
            android:label="读写NFC标签的纯文本数据"
            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>
        <activity
            android:name=".ShowNFCTagContentActivity"
            android:label="显示NFC标签内容"
            android:launchMode="singleTask" />

        <activity
            android:name=".InputTextActivity"
            android:label="向NFC标签写入文本" />

    </application>

</manifest>

 DEMO:下载地址：http://download.csdn.net/detail/androidsj/7678947