我正在尝试在后台监视用户磁盘上的文件夹,就像您可以使用JobScheduler和contentobserver监视库更改一样.我想为任何指定的目录执行此操作.但是,当目录有任何文件更改时,我无法弄清楚如何接收广播.
解决方法
为了创建系统范围的文件观察器,您需要做几件事.
首先
您必须创建一个将在启动时启动并始终运行的服务.
为了实现这一点,你必须创建一个BroadcastReceiver,注册它以接收ACTION_BOOT_COMPLETED和RECEIVE_BOOT_COMPLETED权限给你的清单
public class StartupReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context,Intent intent) {
Intent myIntent = new Intent(context,FileSystemObserverService.class);
context.startService(myIntent);
}
}
在你的清单中
<manifest >
<application >
<service
android:name=".FileSystemObserverService"
android:enabled="true"
android:exported="true" >
</service>
<!-- Declaring broadcast receiver for BOOT_COMPLETED event. -->
<receiver android:name=".StartupReceiver" android:enabled="true" android:exported="false">
<intent-filter>
<action android:name="android.intent.action.BOOT_COMPLETED"/>
</intent-filter>
</receiver>
</application>
<!-- Adding the permission -->
<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
</manifest>
其次
该服务必须实现android.os.FileObserver类.由于android.os.FileObserver只观察您发送给它的路径并且没有观察路径的子目录,因此您必须扩展它并向其添加SingleFileObserver观察者.您还必须在优先级设置为低的另一个线程中运行观察
public class FileSystemObserverService extends Service {
@Override
public IBinder onBind(Intent intent) {
// TODO: Return the communication channel to the service.
throw new UnsupportedOperationException("Not yet implemented");
}
@Override
public int onStartCommand(Intent intent,int flags,int startId) {
observe();
return super.onStartCommand(intent,flags,startId);
}
public File getInternalStoragePath(){
File parent=Environment.getExternalStorageDirectory().getParentFile();
File external=Environment.getExternalStorageDirectory();
File[] files =parent.listFiles();
File internal=null;
if(files!=null){
for(int i=0;i<files.length;i++){
if(files[i].getName().toLowerCase().startsWith("sdcard")&&!files[i].equals(external)){
internal=files[i];
}
}
}
return internal;
}
public File getExtenerStoragePath(){
return Environment.getExternalStorageDirectory();
}
public void observe(){
Thread t=new Thread(new Runnable(){
@Override
public void run() {
//File[] listOfFiles = new File(path).listFiles();
File str=getInternalStoragePath();
if(str!=null){
internalPath=str.getAbsolutePath();
new Obsever(internalPath).startWatching();
}
str=getExtenerStoragePath();
if(str!=null){
externalPath=str.getAbsolutePath();
new Obsever(externalPath).startWatching();
}
}});
t.setPriority(Thread.MIN_PRIORITY);
t.start();
}
class Obsever extends FileObserver{
List<SingleFileObserver> mObservers;
String mPath;
int mMask;
public Obsever(String path) {
// TODO Auto-generated constructor stub
this(path,ALL_EVENTS);
}
public Obsever(String path,int mask) {
super(path,mask);
mPath =path;
mMask =mask;
// TODO Auto-generated constructor stub
}
@Override
public void startWatching() {
// TODO Auto-generated method stub
if(mObservers!=null)
return;
mObservers= new ArrayList<SingleFileObserver>();
Stack<String> stack= new Stack<String>();
stack.push(mPath);
while(!stack.empty()){
String parent = stack.pop();
mObservers.add(new SingleFileObserver(parent,mMask));
File path = new File(parent);
File[] files = path.listFiles();
if(files==null) continue;
for(int i=0;i<files.length;++i){
if(files[i].isDirectory()&&!files[i].getName().equals(".")&&!files[i].getName().equals("..")){
stack.push(files[i].getPath());
}
}
}
for(int i=0;i<mObservers.size();i++){
mObservers.get(i).startWatching();
}
}
@Override
public void stopWatching() {
// TODO Auto-generated method stub
if(mObservers==null)
return;
for(int i=0;i<mObservers.size();++i){
mObservers.get(i).stopWatching();
}
mObservers.clear();
mObservers=null;
}
@Override
public void onEvent(int event,final String path) {
if(event==FileObserver.OPEN){
//do whatever you want
}
else if(event==FileObserver.CREATE){
//do whatever you want
}
else if(event==FileObserver.DELETE_SELF||event==FileObserver.DELETE){
//do whatever you want
}
else if(event==FileObserver.MOVE_SELF||event==FileObserver.MOVED_FROM||event==FileObserver.MOVED_TO){
//do whatever you want
}
}
private class SingleFileObserver extends FileObserver{
private String mPath;
public SingleFileObserver(String path,int mask) {
super(path,mask);
// TODO Auto-generated constructor stub
mPath=path;
}
@Override
public void onEvent(int event,String path) {
// TODO Auto-generated method stub
String newPath=mPath+"/"+path;
Obsever.this.onEvent(event,newPath);
}
}
}
