diff --git a/blogs/Android/Framework/Interview/综合性面试题/Framework 设计模式.md b/blogs/Android/Framework/Interview/综合性面试题/Framework 设计模式.md new file mode 100644 index 0000000..f3e4e42 --- /dev/null +++ b/blogs/Android/Framework/Interview/综合性面试题/Framework 设计模式.md @@ -0,0 +1,150 @@ +--- +Framework 用到了哪些设计模式? +--- + +1. 是否熟悉常用的设计模式 +2. 是否对 Framework 源码有所了解 +3. 是否善于学习和总结 + +#### 单例模式 + +```java +private static final Singleton gDefault = new Singleton(){ + protected IActivityManager create(){ + IBinder b = ServiceManager.getService("activity"); + IActivityManager am = asInterface(b); + return am; + } +} +static public IActivityManager getDefault(){ + return gDefault.get(); +} +``` + +```java +// 线程间单例 +private static final ThreadLocal sThreadInstance = new ThreadLocal(){ + @Override + protected Choreographer initialValue(){ + Looper looper = Looper.myLooper(); + return new Choreographer(looper); + } +} +public static Choreographer getInstance(){ + return sThreadInstance.get(); +} +``` + +```c++ +// 进程间单例 +// 单例:ServiceManager 中间人:Binder 驱动 +int main(int argc, char **argv){ + struct binder_state *bs; + bs = binder_open(128*1024); + binder_become_context_manager(bs); +} +private static IServiceManager getIServiceManager(){ + if(sServiceManager != null){ + return sServiceManager; + } + sServiceManager = ServiceManagerNative.asInterface(BinderInternal.getContextObject()); + return sServiceManager; +} +sp ProcessState::getContextObject(const sp&){ + return getStrongProxyForHandle(0); +} +``` + +#### 观察者模式 + +```java +public class ContentObservable extends Observable{ + @OVerride + public void registerObserver(ContentObserver observer){ + super.registerObserver(observer)l + } + public void notifyChange(boolean selfChange){ + synchronized(mObservers){ + for(ContentObserver observer: mObservers){ + observer.onChange(selfChange, null); + } + } + } +} +void registerContentObserver(..., ContentObserver obsserver, ...){ + getContentService().registerContentObserver(..., observer.getContentObserver(), ...); +} +public IContentOnserver getContentObserver(){ + synchronized(mLock){ + if(mTransport == null){ + mTransport = new Transport(this); + } + return mTransport; + } +} +private static final class Transport extends IContentObserver.Stub{ + private ContentObserver mContentObserver; + public Transport(ContentObserver contentObserver){ + mContentObserver = contentObserver; + } + @Override + public void onChange(boolean selfChange, Uri uri, int userId){ + ContentObserver contentObserver = mContentObserver; + if(contentObserver!=null){ + contentObserver.dispatchChange(selfChange, uri, userId); + } + } +} +``` + +#### 代理模式 + +静态代理: + +```java +class ActivityManagerProxy implements IActivityManager{ + private IBinder mRemote; + public ActivityManagerProxy(IBinder remote){ + mRemote. = remote; + } +} +class ActivityManagerNative extends Binder implements IActivityManager{ + static public IActivityManager asInterface(IBinder obj){ + if(obj == null){ + return null; + } + IActivityManager in = (IActivityManager)obj.queryLocalInterface(descriptor); + if(in != null){ + return in; + } + return new ActivityManagerProxy(obj); + } +} + +int startActivity(IApplicationThread caller, ...) throws RemoteException{ + Parcel data = Parcel.obtain(); + Parcel reply = Parcel.obtain(); + + mRemote.transact(START_ACTIVITY_TRANSACTION, data, reply, 0); +} +``` + +动态代理: + +```java +public class Decorator implements InvocationHandler{ + private final T mObject; + private final DecoratorListener mListener; + + public static T newInstance(T obj, DecoratorListener listener){ + return (T)Proxy.newProxyInstance(obj.getClass().getClassLoader(), + obj.getClass().getInterfaces(),new Decorator(obj, listener)); + } + + private Decorator(T obj, DecoratorListener listener){ + this.mObject = obj; + this.mListener = listener; + } +} +``` +