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() + "\nmax size:" + ndef.getMaxSize()
                 + "bytes\n\n";

         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() + "\n\ntext\n"
                             + 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