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Fresco.initializeDrawee()的过程

2016-04-30 10:47 369 查看
继续上篇博客的分析Fresco.initializeDrawee()
sDraweeControllerBuilderSupplier = new PipelineDraweeControllerBuilderSupplier(context);
SimpleDraweeView.initialize(sDraweeControllerBuilderSupplier);


初始化了一个sDraweeControllerBuilderSupplier
将此sDraweeControllerBuilderSupplier用于初始化SimpleDraweeView

还是老的分析思路: 一步一步分析


4.2.1.2.1 sDraweeControllerBuilderSupplier初始化的过程

public PipelineDraweeControllerBuilderSupplier(Context context) {
this(context, ImagePipelineFactory.getInstance());
}

public PipelineDraweeControllerBuilderSupplier(
Context context,
ImagePipelineFactory imagePipelineFactory) {
this(context, imagePipelineFactory, null);
}

public PipelineDraweeControllerBuilderSupplier(
Context context,
ImagePipelineFactory imagePipelineFactory,
Set<ControllerListener> boundControllerListeners) {
mContext = context;
mImagePipeline = imagePipelineFactory.getImagePipeline();
mPipelineDraweeControllerFactory = new PipelineDraweeControllerFactory(
context.getResources(),
DeferredReleaser.getInstance(),
imagePipelineFactory.getAnimatedDrawableFactory(),
UiThreadImmediateExecutorService.getInstance());
mBoundControllerListeners = boundControllerListeners;
}


构造方法,相互调用,总结过程

获取到了ImagePipelineFactory的实例,经过查看源码,只是将Fresco第一步初始化中的ImagePipelineFactory,获取到了这个实例,这里采用了单例的形式

获取到ImagePipleline,并且保存在这个Supplier中,这个里面代码看似只有这么几行,但是包涵的内容很多,还是先从广度看,然后再从深度看(这个方面作为遗留的Q2,一会儿再看)

*** ImagePipelineFactory.getImagePipeline()源码 ***

public ImagePipeline getImagePipeline() {

if (mImagePipeline == null) {

mImagePipeline =

new ImagePipeline(

getProducerSequenceFactory(),

mConfig.getRequestListeners(),

mConfig.getIsPrefetchEnabledSupplier(),

getBitmapMemoryCache(),

getEncodedMemoryCache(),

mConfig.getCacheKeyFactory());

}

return mImagePipeline;

}

在获取ImagePipeline()中,如果为空,创建了一个

创建了一个PipelineDraweeControllerFactory,并且保存到这个Supplier中

看到这里,我们先继续的广度分析,就是继续的分析SimpleDraweeView.initialize(sDraweeControllerBuilderSupplier)的过程


4.2.1.2.2 SimpleDraweeView.initialize(sDraweeControllerBuilderSupplier)的过程

在上面的分析,我们已经看到sDraweeControllerBuilderSupplier使用的是PipelineDraweeControllerBuilderSupplier

接下来,我们就看SimpleDraweeView.initialize(sDraweeControllerBuilderSupplier)的过程

从下面的代码,我们看到sDraweeControllerBuilderSupplier保存在了SimpleDraweeView中,SimpleDraweeView能够很简单的使用,是因为Fresco帮助我们在这里初始化了很多东西
private static Supplier<? extends SimpleDraweeControllerBuilder> sDraweeControllerBuilderSupplier;

/** Initializes {@link SimpleDraweeView} with supplier of Drawee controller builders. */
public static void initialize(
Supplier<? extends SimpleDraweeControllerBuilder> draweeControllerBuilderSupplier) {
sDraweeControllerBuilderSupplier = draweeControllerBuilderSupplier;
}


接着,以SimpleDraweeView的xml解析的方式来分析初始化的过程,我们发现,这里调用了我们的sDraweeControllerBuilderSupplier的get方法

*** SimpleDraweeView 的xml构造方式源码分析 ***
public SimpleDraweeView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}

private void init() {
if (isInEditMode()) {
return;
}
Preconditions.checkNotNull(
sDraweeControllerBuilderSupplier,
"SimpleDraweeView was not initialized!");
mSimpleDraweeControllerBuilder = sDraweeControllerBuilderSupplier.get();
}


先别着急,我们再接着看,在使用xml解析的方式,我们还用到了一个setImageUri方法,再接着看这个方法,在setImageUri中,创建了一个DraweeController,然后设置给了自身,在构造DraweeController的时候,我们发现,调用了mSimpleDraweeControllerBuilder的build()方法

*** setImageURI(Uri)的源码分析 ***
/**
* Displays an image given by the uri.
*
* @param uri uri of the image
* @undeprecate
*/
@Override
public void setImageURI(Uri uri) {
setImageURI(uri, null);
}

/**
* Displays an image given by the uri.
*
* @param uri uri of the image
* @param callerContext caller context
*/
public void setImageURI(Uri uri, @Nullable Object callerContext) {
DraweeController controller = mSimpleDraweeControllerBuilder
.setCallerContext(callerContext)
.setUri(uri)
.setOldController(getController())
.build();
setController(controller);
}


到这里,我们先总结一下:

SimpleDraweeView中的sDraweeControllerBuilderSupplier是PipelineDraweeControllerBuilderSupplier
SimpleDraweeView中的controller是什么呢?那么这里就需要看看sDraweeControllerBuilderSupplier的get到什么ControllerBuilder?
对应的ControllerBuilder,build出什么controller
controller又是怎么样将提交请求的
遗留的Q2问题什么时候可以分析

看到这几个问题,我们发现,我们的分析,任重而道远


4.2.1.2.3 PipelineDraweeControllerBuilderSupplier的get()分析

这里只是创建了一个PipelineDraweeControllerBuilder,并且这个builder保存了imagePipeline和mPipelineDraweeControllerFactory

*** PipelineDraweeControllerBuilder.get()分析 ***

@Override

public PipelineDraweeControllerBuilder get() {

return new PipelineDraweeControllerBuilder(

mContext,

mPipelineDraweeControllerFactory,

mImagePipeline,

mBoundControllerListeners);

}

*** PipelineDraweeControllerBuilder的构造方法 ***

在这里,我们看不到什么,那么就继续看build()方法吧

public PipelineDraweeControllerBuilder(

Context context,

PipelineDraweeControllerFactory pipelineDraweeControllerFactory,

ImagePipeline imagePipeline,

Set boundControllerListeners) {

super(context, boundControllerListeners);

mImagePipeline = imagePipeline;

mPipelineDraweeControllerFactory = pipelineDraweeControllerFactory;

}

查看build方法时,便已经看到了这个PipelineDraweeControllerBuilder的继承结构

AbstractDraweeControllerBuilder

--| VolleyDraweeControllerBuilder

--| PipelineDraweeControllerBuilder

Volley相关的我们就不看了,这个是和Vollery框架结合使用的,有兴趣可以自己研究下,大同小异

这次直接从方法调用来看即可,这次我们就要看到请求到底是如何产生的了

*** AbstractDraweeControllerBuilder.build()方法源码分析 ***

非核心代码,这次就忽略了,我们主要目的是要看到如何发送请求的,到后面请求如何反馈到前台,我们再详细分析其他代码

在build中,最关键的是buildController(),而在buildController中,最核心的是obtainController(),然后其他的是设置请求的一些信息,比如说设置请求的ImageRequest,其他的是设置重试等等
/** Builds the specified controller. */
@Override
public AbstractDraweeController build() {
validate();

// if only a low-res request is specified, treat it as a final request.
if (mImageRequest == null && mMultiImageRequests == null && mLowResImageRequest != null) {
mImageRequest = mLowResImageRequest;
mLowResImageRequest = null;
}

return buildController();
}

/** Builds a regular controller. */
protected AbstractDraweeController buildController() {
AbstractDraweeController controller = obtainController();
maybeBuildAndSetRetryManager(controller);
maybeAttachListeners(controller);
return controller;
}

/** Concrete builder classes should override this method to return a new controller. */
protected abstract AbstractDraweeController obtainController();


而在这里,发现obtainController()是抽象方法,那么就是找子类呗

*** PipelineDraweeControllerBuilder.obtainController()源码分析 ***

在获取controller的方法中,我们还是以第一次初始化为例,那么就是else的部分,这里就是用mPipelineDraweeControllerFactory创建了一个newController

@Override

protected PipelineDraweeController obtainController() {

DraweeController oldController = getOldController();

PipelineDraweeController controller;

if (oldController instanceof PipelineDraweeController) {

controller = (PipelineDraweeController) oldController;

controller.initialize(

obtainDataSourceSupplier(),

generateUniqueControllerId(),

getCallerContext());

} else {

controller = mPipelineDraweeControllerFactory.newController(

obtainDataSourceSupplier(),

generateUniqueControllerId(),

getCallerContext());

}

return controller;

}

这块要关键的分析了,因为已经到了重点了
controller = mPipelineDraweeControllerFactory.newController(
obtainDataSourceSupplier(),
generateUniqueControllerId(),
getCallerContext());


我们一步一步看

obtainDataSourceSupplier()获取到了一个DataSourceSupplier
然后mPipelineDraweeControllerFactory类new了一个controller

这也没看出来什么,是吧,我们下节就得来点插叙,结合DraweeController和这里的获取Supplier直接的关系,那么基本的请求流程,我们算基本分析结束
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