文件夹变化监听

publicclassRecursiveFileObserverextendsFileObserver{

        /** Only modification events */

        publicstaticint CHANGES_ONLY = CREATE | DELETE | CLOSE_WRITE | MOVE_SELF | MOVED_FROM | MOVED_TO;

        List<SingleFileObserver> mObservers;

        String mPath;

        int mMask;

        publicRecursiveFileObserver(String path){

                this(path, ALL_EVENTS);

        }

        publicRecursiveFileObserver(String path,int mask){

                super(path, mask);

                mPath = path;

                mMask = mask;

        }

        @Override

        publicvoid startWatching(){

                if(mObservers !=null)return;

                mObservers =newArrayList<SingleFileObserver>();

                Stack<String> stack =newStack<String>();

                stack.push(mPath);

                while(!stack.isEmpty()){

                        String parent = stack.pop();

                        mObservers.add(newSingleFileObserver(parent, mMask));

                        File path =newFile(parent);

                        File[] files = path.listFiles();

                        if(null== files)continue;

                        for(File f : files)

                        {

                                if(f.isDirectory()&&!f.getName().equals(".")&&!f.getName().equals("..")){

                                        stack.push(f.getPath());

                                }

                        }

                }

                for(SingleFileObserver sfo : mObservers){

                        sfo.startWatching();

                }

        }

        @Override

        publicvoid stopWatching(){

                if(mObservers ==null)return;

                for(SingleFileObserver sfo : mObservers){

                        sfo.stopWatching();

                }

                mObservers.clear();

                mObservers =null;

        }

        @Override

        publicvoid onEvent(int event,String path){

                switch(event)

                {

                caseFileObserver.ACCESS:

                        Log.i("RecursiveFileObserver","ACCESS: "+ path);

                        break;

                caseFileObserver.ATTRIB:

                        Log.i("RecursiveFileObserver","ATTRIB: "+ path);

                        break;

                caseFileObserver.CLOSE_NOWRITE:

                        Log.i("RecursiveFileObserver","CLOSE_NOWRITE: "+ path);

                        break;

                caseFileObserver.CLOSE_WRITE:

                        Log.i("RecursiveFileObserver","CLOSE_WRITE: "+ path);

                        break;

                caseFileObserver.CREATE:

                        Log.i("RecursiveFileObserver","CREATE: "+ path);

                        break;

                caseFileObserver.DELETE:

                        Log.i("RecursiveFileObserver","DELETE: "+ path);

                        break;

                caseFileObserver.DELETE_SELF:

                        Log.i("RecursiveFileObserver","DELETE_SELF: "+ path);

                        break;

                caseFileObserver.MODIFY:

                        Log.i("RecursiveFileObserver","MODIFY: "+ path);

                        break;

                caseFileObserver.MOVE_SELF:

                        Log.i("RecursiveFileObserver","MOVE_SELF: "+ path);

                        break;

                caseFileObserver.MOVED_FROM:

                        Log.i("RecursiveFileObserver","MOVED_FROM: "+ path);

                        break;

                caseFileObserver.MOVED_TO:

                        Log.i("RecursiveFileObserver","MOVED_TO: "+ path);

                        break;

                caseFileObserver.OPEN:

                        Log.i("RecursiveFileObserver","OPEN: "+ path);

                        break;

                default:

                        Log.i("RecursiveFileObserver","DEFAULT("+ event +"): "+ path);

                        break;

                }

        }

        /**

         * Monitor single directory and dispatch all events to its parent, with full path.

         * @author              uestc.Mobius <mobius@toraleap.com>

         * @version     2011.0121

         */

        classSingleFileObserverextendsFileObserver{

                String mPath;

                publicSingleFileObserver(String path){

                        this(path, ALL_EVENTS);

                        mPath = path;

                }

                publicSingleFileObserver(String path,int mask){

                        super(path, mask);

                        mPath = path;

                }

                @Override

                publicvoid onEvent(int event,String path){

                        String newPath = mPath +"/"+ path;

                        RecursiveFileObserver.this.onEvent(event, newPath);

                }

        }

}

注意：
1、必须保持FileObserver的引用才能监听文件，因此最好放到service中，并且把引用都保存起来；
2、FileObserver需要给每个文件夹设置监听器，因为它自己不能递归监听。