14、NFC技术：使用Android Beam技术传输文本

  1 import java.nio.charset.Charset;
  2 import java.util.Locale;
  3 
  4 import android.app.Activity;
  5 import android.app.PendingIntent;
  6 import android.content.Intent;
  7 import android.nfc.NdefMessage;
  8 import android.nfc.NdefRecord;
  9 import android.nfc.NfcAdapter;
 10 import android.nfc.NfcAdapter.CreateNdefMessageCallback;
 11 import android.nfc.NfcAdapter.OnNdefPushCompleteCallback;
 12 import android.nfc.NfcEvent;
 13 import android.os.Bundle;
 14 import android.os.Parcelable;
 15 import android.util.Log;
 16 import android.widget.EditText;
 17 import android.widget.Toast;
 18 
 19 /**
 20  * 两部android手机，进行传入文本信息。
 21  * @author dr
 22  *
 23  */
 24 public class AndroidBeamMainActivity extends Activity implements
 25         CreateNdefMessageCallback, OnNdefPushCompleteCallback {
 26 
 27     private EditText mBeamText;
 28 
 29     private NfcAdapter mNfcAdapter;
 30     private PendingIntent mPendingIntent;
 31 
 32     @Override
 33     public void onCreate(Bundle savedInstanceState) {
 34         super.onCreate(savedInstanceState);
 35 
 36         setContentView(R.layout.activity_android_beam);
 37         mBeamText = (EditText) findViewById(R.id.edittext_beam_text);
 38         
 39         mNfcAdapter = mNfcAdapter.getDefaultAdapter(this);
 40         mPendingIntent = PendingIntent.getActivity(this, 0, new Intent(this,
 41                 getClass()), 0);
 42 
 43         mNfcAdapter.setNdefPushMessageCallback(this, this);
 44         mNfcAdapter.setOnNdefPushCompleteCallback(this, this);
 45     }
 46 
 47     @Override    /** 窗口处理完成 */
 48     public void onNdefPushComplete(NfcEvent event) {
 49         Log.d("message", "complete");
 50     }
 51 
 52     @Override  /** 如果另外一台手机，靠近当前这部手机 */
 53     public NdefMessage createNdefMessage(NfcEvent event) {
 54         String text = mBeamText.getText().toString().trim();
 55         if ("".equals(text))
 56             text = "默认文本";
 57         /*
 58          *  "com.android.calculator2"  官方原生计算器包。
 59          *  当另外一部手机靠近这部手机时，会启动计算器。
 60          *  
 61          * NdefMessage ndefMessage = new NdefMessage( new NdefRecord[] {
 62          * NdefRecord .createApplicationRecord("com.android.calculator2") });
 63          */
 64         NdefMessage ndefMessage = new NdefMessage(
 65                 new NdefRecord[] { createTextRecord(text) });
 66 
 67         return ndefMessage;
 68     }
 69 
 70     @Override
 71     public void onResume() {
 72         super.onResume();
 73         if (mNfcAdapter != null)
 74             mNfcAdapter.enableForegroundDispatch(this, mPendingIntent, null,
 75                     null);
 76     }
 77 
 78     @Override
 79     public void onPause() {
 80         super.onPause();
 81         if (mNfcAdapter != null)
 82             mNfcAdapter.disableForegroundDispatch(this);
 83     }
 84 
 85     @Override
 86     public void onNewIntent(Intent intent) {
 87         // 用于显示接收手机的信息。如果接收手机没有打开，会默认调用系统的黑界面。
 88         processIntent(intent);
 89     }
 90 
 91     /** 根据文本创建 NdefRecord 这个对象 */
 92     public NdefRecord createTextRecord(String text) {
 93         byte[] langBytes = Locale.CHINA.getLanguage().getBytes(
 94                 Charset.forName("US-ASCII"));
 95         Charset utfEncoding = Charset.forName("UTF-8");
 96         byte[] textBytes = text.getBytes(utfEncoding);
 97         int utfBit = 0;
 98         char status = (char) (utfBit + langBytes.length);
 99         byte[] data = new byte[1 + langBytes.length + textBytes.length];
100         data[0] = (byte) status;
101         System.arraycopy(langBytes, 0, data, 1, langBytes.length);
102         System.arraycopy(textBytes, 0, data, 1 + langBytes.length,
103                 textBytes.length);
104         NdefRecord record = new NdefRecord(NdefRecord.TNF_WELL_KNOWN,
105                 NdefRecord.RTD_TEXT, new byte[0], data);
106 
107         return record;
108     }
109 
110     void processIntent(Intent intent) {
111         Parcelable[] rawMsgs = intent
112                 .getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);
113 
114         NdefMessage msg = (NdefMessage) rawMsgs[0];
115         String text = TextRecord.parse(msg.getRecords()[0]).getText();
116         Toast.makeText(this, text, Toast.LENGTH_LONG).show();
117     }
118 }  

 1 import java.io.UnsupportedEncodingException;
 2 import java.util.Arrays;
 3 import android.nfc.NdefRecord;
 4 
 5 public class TextRecord {
 6     private final String mText;
 7 
 8     private TextRecord(String text) {
 9         mText = text;
10     }
11 
12     public String getText() {
13         return mText;
14     }
15 
16     // 将纯文本内容从NdefRecord对象中解析出来
17     public static TextRecord parse(NdefRecord record) {
18 
19         if (record.getTnf() != NdefRecord.TNF_WELL_KNOWN)
20             return null;
21         if (!Arrays.equals(record.getType(), NdefRecord.RTD_TEXT))
22             return null;
23 
24         try {
25             byte[] payload = record.getPayload();
26             /*
27              * payload[0] contains the "Status Byte Encodings" field, per the
28              * NFC Forum "Text Record Type Definition" section 3.2.1.
29              * 
30              * bit7 is the Text Encoding Field.
31              * 
32              * if (Bit_7 == 0): The text is encoded in UTF-8 if (Bit_7 == 1):
33              * The text is encoded in UTF16
34              * 
35              * Bit_6 is reserved for future use and must be set to zero.
36              * 
37              * Bits 5 to 0 are the length of the IANA language code.
38              */
39             String textEncoding = ((payload[0] & 0x80) == 0) ? "UTF-8"
40                     : "UTF-16";
41             int languageCodeLength = payload[0] & 0x3f;
42             String languageCode = new String(payload, 1, languageCodeLength,
43                     "US-ASCII");
44             String text = new String(payload, languageCodeLength + 1,
45                     payload.length - languageCodeLength - 1, textEncoding);
46             return new TextRecord(text);
47         } catch (UnsupportedEncodingException e) {
48             // should never happen unless we get a malformed tag.
49             throw new IllegalArgumentException(e);
50         }
51     }
52 
53 }  

 1 <?xml version="1.0" encoding="utf-8"?>
 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 3     android:layout_width="match_parent"
 4     android:layout_height="match_parent"
 5     android:orientation="vertical" >
 6 
 7     <EditText
 8         android:id="@+id/edittext_beam_text"
 9         android:layout_width="match_parent"
10         android:layout_height="wrap_content"
11         android:hint="请输入要传输的文本"/>
12 
13     <TextView
14         android:layout_width="match_parent"
15         android:layout_height="wrap_content"
16         android:layout_marginBottom="5dp"
17         android:text="请将当前设备靠近其他NFC设备，别忘了触摸屏幕哦！"
18         android:textSize="16sp" />
19 
20     <ImageView
21         android:layout_width="match_parent"
22         android:layout_height="match_parent"
23         android:layout_margin="10dp"
24         android:src="@drawable/read_nfc_tag" />
25 
26 </LinearLayout>