Fresco知识点笔记01

根项目build.gradel中的配置

 repositories {
 mavenLocal()
 jcenter()
 mavenCentral()
 }
 

Gradle支持从maven中央仓库和JCenter上获取构件，那这两者有什么区别呢？
maven中央仓库（http://repo1.maven.org/maven2/）是由Sonatype公司提供的服务，它是Apache Maven、SBT和其他构建系统的默认仓库，并能很容易被Apache Ant/Ivy、Gradle和其他工具所使用。开源组织例如Apache软件基金会、Eclipse基金会、JBoss和很多个人开源项目都将构件发布到中央仓库。 maven中央仓库已经将内容浏览功能禁掉了，可在http://search.maven.org/查询构件。
https://jcenter.bintray.com ）是由JFrog公司提供的Bintray中的Java仓库。它是当前世界上最大的Java和Android开源软件构件仓库。 所有内容都通过内容分发网络（CDN）使用加密https连接获取。JCenter是Goovy Grape内的默认仓库，Gradle内建支持（jcenter()仓库），非常易于在（可能除了Maven之外的）其他构建工具内进行配置。
JCenter相比mavenCenter构件更多，性能也更好。但还是有些构件仅存在mavenCenter中。

 project.ext {
 buildToolsVersion = "${BUILD_TOOLS_VERSION}"
 compileSdkVersion = COMPILE_SDK_VERSION.toInteger()
 minSdkVersion = MIN_SDK_VERSION;
 targetSdkVersion = TARGET_SDK_VERSION;
 preDexLibs = !project.hasProperty('disablePreDex');
 }
 

"${BUILD_TOOLS_VERSION}"引入gradle.properties中的字符属性，MIN_SDK_VERSION引入int属性，gradle.properties把整个源码中用到的常量都给整合了，方便以后维护。

 android {
 buildToolsVersion rootProject.ext.buildToolsVersion
 compileSdkVersion rootProject.ext.compileSdkVersion
 
 
defaultConfig {
    applicationId "com.facebook.samples.demo"
    minSdkVersion rootProject.ext.minSdkVersion
    targetSdkVersion rootProject.ext.targetSdkVersion
    versionCode 1
    versionName "${VERSION_NAME}"

    testApplicationId "com.facebook.samples.demo.test"
    testInstrumentationRunner "android.test.InstrumentationTestRunner"
}
 
 
}
 

以buildToolsVersion rootProject.ext.buildToolsVersion为例buildToolsVersion引用了以上在根项目中的配置值，其他类似。

Presco的配置项ImagePipelineConfig采用是建造者模式，以下是ImagePipelineConfig的构造函数

 private ImagePipelineConfig(Builder builder) {
 mAnimatedImageFactory = builder.mAnimatedImageFactory;
 mBitmapMemoryCacheParamsSupplier =
 builder.mBitmapMemoryCacheParamsSupplier == null ?
 new DefaultBitmapMemoryCacheParamsSupplier(
 (ActivityManager) builder.mContext.getSystemService(Context.ACTIVITY_SERVICE)) :
 builder.mBitmapMemoryCacheParamsSupplier;
 mBitmapConfig =
 builder.mBitmapConfig == null ?
 Bitmap.Config.ARGB_8888 :
 builder.mBitmapConfig;
 mCacheKeyFactory =
 builder.mCacheKeyFactory == null ?
 DefaultCacheKeyFactory.getInstance() :
 builder.mCacheKeyFactory;
 mContext = Preconditions.checkNotNull(builder.mContext);
 mDecodeMemoryFileEnabled = builder.mDecodeMemoryFileEnabled;
 mFileCacheFactory = builder.mFileCacheFactory == null ?
 new DiskStorageCacheFactory(new DynamicDefaultDiskStorageFactory()) :
 builder.mFileCacheFactory;
 mDownsampleEnabled = builder.mDownsampleEnabled;
 mEncodedMemoryCacheParamsSupplier =
 builder.mEncodedMemoryCacheParamsSupplier == null ?
 new DefaultEncodedMemoryCacheParamsSupplier() :
 builder.mEncodedMemoryCacheParamsSupplier;
 mImageCacheStatsTracker =
 builder.mImageCacheStatsTracker == null ?
 NoOpImageCacheStatsTracker.getInstance() :
 builder.mImageCacheStatsTracker;
 mImageDecoder = builder.mImageDecoder;
 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;
 mNetworkFetcher =
 builder.mNetworkFetcher == null ?
 new HttpUrlConnectionNetworkFetcher() :
 builder.mNetworkFetcher;
 mPlatformBitmapFactory = builder.mPlatformBitmapFactory;
 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;
 
 
// Below this comment can't be built in alphabetical order, because of dependencies
 int numCpuBoundThreads = mPoolFactory.getFlexByteArrayPoolMaxNumThreads();
 mExecutorSupplier =
 builder.mExecutorSupplier == null ?
 new DefaultExecutorSupplier(numCpuBoundThreads) : builder.mExecutorSupplier;
 mImagePipelineExperiments = builder.mExperimentsBuilder.build();
 }
 

上述源码主要是设置了一些默认的配置对象，相关知识点
1、ActivityManager框架解析--ImagePipelineConfig
2、Executors.newFixedThreadPool实例-HttpUrlConnectionNetworkFetcher
3、空集合声明小技巧List list = Collections.EMPTY_LIST
4、Java ThreadFactory接口用法--DefaultExecutorSupplier

 /** Initializes Fresco with the default config. */
 public static void initialize(Context context) {
 ImagePipelineFactory.initialize(context);
 initializeDrawee(context);
 }
 
 
/** Initializes Fresco with the specified config. */
 public static void initialize(Context context, ImagePipelineConfig imagePipelineConfig) {
 ImagePipelineFactory.initialize(imagePipelineConfig);
 initializeDrawee(context);
 }
 

以上代码是Presco初始化代码，一个是默认配置的，一个是传递自定义配置的,以下是初始化过程中的知识点。
1、@NotThreadSafe 表示这个类不是线程安全的。如果是线程安全的非要打上这个注解，那也不会报错。(注释详解)--ImagePipelineFactory
2、Java.util.ArrayDeque类--ThreadHandoffProducerQueue
3、Predicate predicate后期补充--MemoryCache/AndroidPredicates
4、AnimatedFactoryProvider获取动画工厂实体的时候用到了反射
5、Java WeakReference的理解与使用--ActivityListenerManager
6、Executor实现AbstractExecutorService实现分析--CallerThreadExecutor
7、AtomicInteger的并发处理--StatefulRunnable
8、MediaUtils包含对mime类型的一些处理
9、IdentityHashMap 使用总结-SharedReference
10、使用isInEditMode解决可视化编辑器无法识别自定义控件的问题