两个经典的递归的方法

第一个创建文件：

 

public void addObserverLocked(Uri uri, IContentObserver observer,
                boolean notifyForDescendents, Object observersLock) {
            addObserverLocked(uri, 0, observer, notifyForDescendents, observersLock);
        }

        private void addObserverLocked(Uri uri, int index, IContentObserver observer,
                boolean notifyForDescendents, Object observersLock) {
            // If this is the leaf node add the observer
            if (index == countUriSegments(uri)) {
                mObservers.add(new ObserverEntry(observer, notifyForDescendents, observersLock));
                return;
            }

            // Look to see if the proper child already exists
            String segment = getUriSegment(uri, index);
            if (segment == null) {
                throw new IllegalArgumentException("Invalid Uri (" + uri + ") used for observer");
            }
            int N = mChildren.size();
            for (int i = 0; i < N; i++) {
                ObserverNode node = mChildren.get(i);
                if (node.mName.equals(segment)) {
                    node.addObserverLocked(uri, index + 1, observer, notifyForDescendents, observersLock);
                    return;
                }
            }

            // No child found, create one
            ObserverNode node = new ObserverNode(segment);
            mChildren.add(node);
            node.addObserverLocked(uri, index + 1, observer, notifyForDescendents, observersLock);
        }

 

 

 

第二个解析文件：

 

 

private void collectMyObserversLocked(boolean leaf, IContentObserver observer,
                boolean selfNotify, ArrayList<ObserverCall> calls) {
            int N = mObservers.size();
            IBinder observerBinder = observer == null ? null : observer.asBinder();
            for (int i = 0; i < N; i++) {
                ObserverEntry entry = mObservers.get(i);

                // Don't notify the observer if it sent the notification and isn't interesed
                // in self notifications
                if (entry.observer.asBinder() == observerBinder && !selfNotify) {
                    continue;
                }

                // Make sure the observer is interested in the notification
                if (leaf || (!leaf && entry.notifyForDescendents)) {
                    calls.add(new ObserverCall(this, entry.observer, selfNotify));
                }
            }
        }

        public void collectObserversLocked(Uri uri, int index, IContentObserver observer,
                boolean selfNotify, ArrayList<ObserverCall> calls) {
            String segment = null;
            int segmentCount = countUriSegments(uri);
            if (index >= segmentCount) {
                // This is the leaf node, notify all observers
                collectMyObserversLocked(true, observer, selfNotify, calls);
            } else if (index < segmentCount){
                segment = getUriSegment(uri, index);
                // Notify any observers at this level who are interested in descendents
                collectMyObserversLocked(false, observer, selfNotify, calls);
            }

            int N = mChildren.size();
            for (int i = 0; i < N; i++) {
                ObserverNode node = mChildren.get(i);
                if (segment == null || node.mName.equals(segment)) {
                    // We found the child,
                    node.collectObserversLocked(uri, index + 1, observer, selfNotify, calls);
                    if (segment != null) {
                        break;
                    }
                }
            }
        }

 

 

第三个：数据结构

 

 

 

 

 public static final class ObserverNode {
        private class ObserverEntry implements IBinder.DeathRecipient {
            public final IContentObserver observer;
            public final boolean notifyForDescendents;
            private final Object observersLock;

            public ObserverEntry(IContentObserver o, boolean n, Object observersLock) {
                this.observersLock = observersLock;
                observer = o;
                notifyForDescendents = n;
                try {
                    observer.asBinder().linkToDeath(this, 0);
                } catch (RemoteException e) {
                    binderDied();
                }
            }

            public void binderDied() {
                synchronized (observersLock) {
                    removeObserverLocked(observer);
                }
            }
        }

        public static final int INSERT_TYPE = 0;
        public static final int UPDATE_TYPE = 1;
        public static final int DELETE_TYPE = 2;

        private String mName;
        private ArrayList<ObserverNode> mChildren = new ArrayList<ObserverNode>();
        private ArrayList<ObserverEntry> mObservers = new ArrayList<ObserverEntry>();