15、NFC技术：使用Android Beam技术传输文件

传输文件的API

从Android4.1开始，NfcAdapter类增加了如下两个推送数据的方法。

NfcAdapter.setBeamPushUris

NfcAdapter.setBeamPushUrisCallback

这两个方法的原型如下：

public void setBeamPushUris(Uri[] uris, Activity activity);

public void setBeamPushUrisCallback(CreateBeamUrisCallback callback, Activity activity);

Demo

 import java.io.FileOutputStream;
 import java.io.InputStream;
 
 import android.app.Activity;
 import android.app.PendingIntent;
 import android.content.Intent;
 import android.net.Uri;
 import android.nfc.NfcAdapter;
 import android.nfc.NfcAdapter.CreateBeamUrisCallback;
 import android.nfc.NfcEvent;
 import android.os.Bundle;
 
 public class NFCFileActivity extends Activity implements CreateBeamUrisCallback {
     private NfcAdapter mNfcAdapter;
     private PendingIntent mPendingIntent;
     private final String targetFilename = "/sdcard/temp_icon.png";
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_nfcfile);
 
         mNfcAdapter = mNfcAdapter.getDefaultAdapter(this);
         mPendingIntent = PendingIntent.getActivity(this, 0, new Intent(this,
                 getClass()), 0);
 
         try {
             InputStream is = getResources().getAssets().open("icon.png");
             FileOutputStream fos = new FileOutputStream(targetFilename);
             byte[] buffer = new byte[10000];
             int n = is.read(buffer);
             fos.write(buffer, 0, n);
             fos.close();
             is.close();
         } catch (Exception e) {
 
         }
         mNfcAdapter.setBeamPushUrisCallback(this, this);
     }
 
     @Override
     public Uri[] createBeamUris(NfcEvent event) {
         Uri[] uris = new Uri[1];
         Uri uri = Uri.parse("file://" + targetFilename);
         uris[0] = uri;
         return uris;
     }
 
 }

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

其实内部是蓝牙在传输,NFC已经不起作用了，可以相隔一定距离，即使NFC中断也没关系，因为是蓝牙在传输。