如果通过Android Beam file transfer将大量的文件从一个device发送到另外一个device呢？
首先在manifest文件中定义NFC的权限和feature.
<uses-permission android:name="android.permission.NFC" />
<uses-feature android:name="android.hardware.nfc"
android:required="true" />
android:required="true" 也可以设定为fals，这样的话就需要在runtime时来判断hw是否support NFC
code如下：
PackageManager.hasSystemFeature(PackageManager.FEATURE_NFC)
定义使用外部存储的权限。
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
Android Beam file transfer不support FileProvider.getUriForFile返回的URI。因此我们必须实现一个回调函数来返回Uri
这个回调函数是NfcAdapter.CreateBeamUrisCallback中的 createBeamUris()。
cide如下:
public class MainActivity extends Activity {
...
// List of URIs to provide to Android Beam
private Uri[] mFileUris = new Uri[10];
...
/**
* Callback that Android Beam file transfer calls to get
* files to share
*/
private class FileUriCallback implements
NfcAdapter.CreateBeamUrisCallback {
public FileUriCallback() {
}
/**
* Create content URIs as needed to share with another device
*/
@Override
public Uri[] createBeamUris(NfcEvent event) {
return mFileUris;
}
}
...
}
然后调用 setBeamPushUrisCallback() 来设定callback ，例子如下：
public class MainActivity extends Activity {
...
// Instance that returns available files from this app
private FileUriCallback mFileUriCallback;
...
@Override
protected void onCreate(Bundle savedInstanceState) {
...
// Android Beam file transfer is available, continue
...
mNfcAdapter = NfcAdapter.getDefaultAdapter(this);
/*
* Instantiate a new FileUriCallback to handle requests for
* URIs
*/
mFileUriCallback = new FileUriCallback();
// Set the dynamic callback for URI requests.
mNfcAdapter.setBeamPushUrisCallback(mFileUriCallback,this);
...
}
...
}
如果指定要发送文件的uri呢？
/*
* Create a list of URIs, get a File,
* and set its permissions
*/
private Uri[] mFileUris = new Uri[10];
String transferFile = "transferimage.jpg";
File extDir = getExternalFilesDir(null);
File requestFile = new File(extDir, transferFile);
requestFile.setReadable(true, false);
// Get a URI for the File and add it to the list of URIs
fileUri = Uri.fromFile(requestFile);
if (fileUri != null) {
mFileUris[0] = fileUri;
} else {
Log.e("My Activity", "No File URI available for file.");
}
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