Android使用FileObserver对sdcard文件或文件夹监控

Android系统API提供了FileObserver抽象类（Linux的INotify机制）来监听系统/sdcard中的文件或文件夹，

FileObserver类能对sdcard中的文件及文件夹的打开、创建、移动和删除操作进行监控。下面看看代码实现：

packagecom.orgcent.filelistener;

import android.app.Activity ;
import android.os.Bundle ;
import android.os.Environment ;
import android.os.FileObserver ;

public class AndroidFileListenerActivity extends Activity {
private FileObserver mFileObserver ;

/** Called when the activity is first created. */
@Override
public void onCreate ( Bundle savedInstanceState ) {
super . onCreate ( savedInstanceState ) ;
setContentView ( R. layout . main ) ;

if ( null == mFileObserver ) {
mFileObserver = new SDCardFileObserver ( Environment . getExternalStorageDirectory ( ) . getPath ( ) ) ;
mFileObserver. startWatching ( ) ; //开始监听
}
}

public void onDestory ( ) {
if ( null != mFileObserver ) mFileObserver. stopWatching ( ) ; //停止监听
}

static class SDCardFileObserver extends FileObserver {
//mask:指定要监听的事件类型，默认为FileObserver.ALL_EVENTS
public SDCardFileObserver ( String path, int mask ) {
super ( path, mask ) ;
}

public SDCardFileObserver ( String path ) {
super ( path ) ;
}

@Override
public void onEvent ( int event, String path ) {
final int action = event & FileObserver. ALL_EVENTS ;
switch ( action ) {
case FileObserver. ACCESS :
System . out . println ( "event: 文件或目录被访问, path: " + path ) ;
break ;

case FileObserver. DELETE :
System . out . println ( "event: 文件或目录被删除, path: " + path ) ;
break ;

case FileObserver. OPEN :
System . out . println ( "event: 文件或目录被打开, path: " + path ) ;
break ;

case FileObserver. MODIFY :
System . out . println ( "event: 文件或目录被修改, path: " + path ) ;
break ;
}
}

}
}