4.2 Fresco客户端与服务端的交互(一) 解决Q1问题
从这篇博客开始,我们开始讨论客户端与服务端是如何交互的,这个交互的入口,我们从Q1问题入手(博客按照这样的问题入手,是因为当时我也是从这里好奇,才开始分析如何交互的,这样避免了思维的跳跃性)
既然我们想从这里入手,那么还是以controller的请求入手,因为请求是从这里发出去的,那么肯定入口就存在于AbstractDraweeController.submitRequest()方法,上源码: 在刚刚查看源码时,我们并没有提及到getDataSource()方法是如何实现的,我们先再浏览一遍submitRequest方法protected void submitRequest() { mEventTracker.recordEvent(Event.ON_DATASOURCE_SUBMIT); getControllerListener().onSubmit(mId, mCallerContext); mSettableDraweeHierarchy.setProgress(0, true); mIsRequestSubmitted = true; mHasFetchFailed = false; // ------------疑问点---- mDataSource = getDataSource(); if (FLog.isLoggable(FLog.VERBOSE)) { FLog.v( TAG, "controller %x %s: submitRequest: dataSource: %x", System.identityHashCode(this), mId, System.identityHashCode(mDataSource)); } final String id = mId; final boolean wasImmediate = mDataSource.hasResult(); final DataSubscriberdataSubscriber = new BaseDataSubscriber () { @Override public void onNewResultImpl(DataSource dataSource) { // isFinished must be obtained before image, otherwise we might set intermediate result // as final image. boolean isFinished = dataSource.isFinished(); float progress = dataSource.getProgress(); T image = dataSource.getResult(); if (image != null) { onNewResultInternal(id, dataSource, image, progress, isFinished, wasImmediate); } else if (isFinished) { onFailureInternal(id, dataSource, new NullPointerException(), /* isFinished */ true); } } @Override public void onFailureImpl(DataSource dataSource) { onFailureInternal(id, dataSource, dataSource.getFailureCause(), /* isFinished */ true); } @Override public void onProgressUpdate(DataSource dataSource) { boolean isFinished = dataSource.isFinished(); float progress = dataSource.getProgress(); onProgressUpdateInternal(id, dataSource, progress, isFinished); } }; mDataSource.subscribe(dataSubscriber, mUiThreadImmediateExecutor); }
在看到getDataSource方法时,我们查看其方法,发现是抽象方法,查看类的继承关系图,得知,实现类有两个PipelineDraweeController和VolleyDraweeController,这个就遇到点困难了,到底采用的是哪个呢?到这里就卡壳了,那么如何处理呢?我们要回到我们起点了,就是在写demo的时候,我们一般在Application 的实现类中的onCreate方法中,调用Fresco.initialize()方法,不得不从这里开始看,因为所有的初始化信息,是在这里实现的(这可不是步步高打火机,那里不会点哪里,哈哈哈)
4.2.1 Fresco初始化的过程
为了要了解getDataSource()方法使用的是哪个实现类,我们从Fresco.initialize()方法入手,分析Fresco初始化的过程
在书写demo的时候,从官方的说明中,已经得知,一般是在Application的onCreate()方法中调用Fresco.initialize()方法,那么这里做了什么样的操作呢?从方法名也可知,这是做了初始化,但是具体需要初始化那些信息呢? *** Fresco.initialize() 源码 ***/** Initializes Fresco with the default config. */ public static void initialize(Context context) { ImagePipelineFactory.initialize(context); initializeDrawee(context); }
从上边的源码可知,初始化了两部分信息
- ImagePipelineFactory做了初始化
- 初始化了Drawee组件信息
note: 个人查看他人代码,可将这个过程当做图来处理,可以做广度查看,也可以按照深度查看,个人建议,广度做了解,了解当前方法的大致流程(对于书写比较规范的框架,一般是见名知意的)然后做每个方法的深度遍历,便了解,边做笔记。
上述已经得知,先做ImagePipelineFactory的初始化,然后初始化Drawee组件,那么就先查看ImagePipelineFactory的初始化
4.2.1.1 ImagePipelineFactory的初始化
*** ImagePipelineFactory.initialize() 源码 ***
/** Initializes {@link ImagePipelineFactory} with default config. */ public static void initialize(Context context) { initialize(ImagePipelineConfig.newBuilder(context).build()); } /** Initializes {@link ImagePipelineFactory} with the specified config. */ public static void initialize(ImagePipelineConfig imagePipelineConfig) { sInstance = new ImagePipelineFactory(imagePipelineConfig); } public ImagePipelineFactory(ImagePipelineConfig config) { mConfig = Preconditions.checkNotNull(config); }
初始化过程,构造了一个ImagePipelineConfig,然后将创建的ImagePipelineConfig用于初始化ImagePipelineFactory,即新建了一个ImagePipelineFactory,新创建的ImagePipelineFactory保存了ImagePipelineConfig的实例
note:这里再次使用了构造者模式
下面需要关注的就变为了ImagePipelineConfig.newBuilder(context).build()的操作
*** ImagePipelineConfig.newBuilder(context).build()的源码 ***
public static Builder newBuilder(Context context) { return new Builder(context); } public static class Builder { ...... private Builder(Context context) { // Doesn't use a setter as always required. mContext = Preconditions.checkNotNull(context); } ...... public ImagePipelineConfig build() { return new ImagePipelineConfig(this); } }
从查看ImagePipelineConfig的上述源码,得知,核心的初始化方法,在Builder.build()方法中,而在builder中创建了一个ImagePipelineConfig对象,而依附的对象为builder,这就到了ImagePipelineConfig的核心处
private ImagePipelineConfig(Builder builder) { mBitmapMemoryCacheParamsSupplier = builder.mBitmapMemoryCacheParamsSupplier == null ? new DefaultBitmapMemoryCacheParamsSupplier( (ActivityManager) builder.mContext.getSystemService(Context.ACTIVITY_SERVICE)) : builder.mBitmapMemoryCacheParamsSupplier; mCacheKeyFactory = builder.mCacheKeyFactory == null ? DefaultCacheKeyFactory.getInstance() : builder.mCacheKeyFactory; mContext = Preconditions.checkNotNull(builder.mContext); mEncodedMemoryCacheParamsSupplier = builder.mEncodedMemoryCacheParamsSupplier == null ? new DefaultEncodedMemoryCacheParamsSupplier() : builder.mEncodedMemoryCacheParamsSupplier; mExecutorSupplier = builder.mExecutorSupplier == null ? new DefaultExecutorSupplier() : builder.mExecutorSupplier; mImageCacheStatsTracker = builder.mImageCacheStatsTracker == null ? NoOpImageCacheStatsTracker.getInstance() : builder.mImageCacheStatsTracker; mIsPrefetchEnabledSupplier = builder.mIsPrefetchEnabledSupplier == null ? new Supplier() { @Override public Boolean get() { return true; } } : builder.mIsPrefetchEnabledSupplier; mMainDiskCacheConfig = builder.mMainDiskCacheConfig == null ? getDefaultMainDiskCacheConfig(builder.mContext) : builder.mMainDiskCacheConfig; mMemoryTrimmableRegistry = builder.mMemoryTrimmableRegistry == null ? NoOpMemoryTrimmableRegistry.getInstance() : builder.mMemoryTrimmableRegistry; mPoolFactory = builder.mPoolFactory == null ? new PoolFactory(PoolConfig.newBuilder().build()) : builder.mPoolFactory; mProgressiveJpegConfig = builder.mProgressiveJpegConfig == null ? new SimpleProgressiveJpegConfig() : builder.mProgressiveJpegConfig; mRequestListeners = builder.mRequestListeners == null ? new HashSet () : builder.mRequestListeners; mResizeAndRotateEnabledForNetwork = builder.mResizeAndRotateEnabledForNetwork; mSmallImageDiskCacheConfig = builder.mSmallImageDiskCacheConfig == null ? mMainDiskCacheConfig : builder.mSmallImageDiskCacheConfig; mAnimatedDrawableUtil = new AnimatedDrawableUtil(); AnimatedDrawableBackendProvider animatedDrawableBackendProvider = new AnimatedDrawableBackendProvider() { @Override public AnimatedDrawableBackend get(AnimatedImageResult imageResult, Rect bounds) { return new AnimatedDrawableBackendImpl(mAnimatedDrawableUtil, imageResult, bounds); } }; GingerbreadBitmapFactory factoryGingerbread = new GingerbreadBitmapFactory(); DalvikBitmapFactory factoryICS = new DalvikBitmapFactory( new EmptyJpegGenerator(mPoolFactory.getPooledByteBufferFactory()), mPoolFactory.getSharedByteArray()); ArtBitmapFactory factoryLollipop = new ArtBitmapFactory(mPoolFactory.getBitmapPool()); mPlatformBitmapFactory = new PlatformBitmapFactory( factoryGingerbread, factoryICS, factoryLollipop); mAnimatedImageFactory = builder.mAnimatedImageFactory == null ? new AnimatedImageFactory(animatedDrawableBackendProvider, mPlatformBitmapFactory) : builder.mAnimatedImageFactory; mImageDecoder = builder.mImageDecoder == null ? new ImageDecoder(mAnimatedImageFactory, mPlatformBitmapFactory) : builder.mImageDecoder; mNetworkFetcher = builder.mNetworkFetcher == null ? new HttpUrlConnectionNetworkFetcher() : builder.mNetworkFetcher; }
上述源码是ImagePipelineConfig的构造,发现此处初始化涉及的信息比较多,为了方便理解,我们先从名称上做一下理解,一会儿用到的时候,再反过来查看相关的详情信息
此类的名称特别形象,就是ImagePipleline的配置类,这其中配置了比较核心的几项- mBitmapMemoryCacheParamsSupplier 内存缓存数据的策略
- mCacheKeyFactory 缓存键值对的获取
- mExecutorSupplier 获取本地读写线程池,网络数据线程池,解码线程池,以及后台线程池
- mImageDecoder 解码器
- 网络数据获取器 ......
ImagePipeLineConfig是一个比较核心的类,通过这个,我们可以得知,Freco初始化时,配置了大量的策略,可配置项很多,也就让我们的使用更加灵活和易于拓展
4.2.1.2 Fresco.initializeDrawee()的过程
private static void initializeDrawee(Context context) { sDraweeControllerBuilderSupplier = new PipelineDraweeControllerBuilderSupplier(context); SimpleDraweeView.initialize(sDraweeControllerBuilderSupplier); }
从上述可知,构造了一个sDraweeControllerBuilderSupplier,然后将这个supplier用于初始化SimpleDraweeView
哎!找到了,发现使用的是PipelineDraweeControllerBuilderSupplier,是不是分析到这里我们就可以结束了?答案是我们只是找到了用于初始化SimpleDraweeView的supplier是PipelineDraweeControllerBuilderSupplier,但是这个做的是怎么样的一个操作呢?我们下节再讨论 下篇链接: Fresco 源码分析(二) Fresco.initializeDrawee()分析 续 http://www.cnblogs.com/pandapan/p/4659960.html安卓源码分析群: Android源码分析QQ1群号:164812238