ps:以下源码分析基于Glide v4.11.0
涉及的类
主要涉及到以下这些类:
- Glide,全局唯一
- RequestManagerRetriever,用于获取RequestManager
- RequestManagerFragment/SupportRequestManagerFragment,用于提供生命周期
- RequestManager,用于管理Request,内部使用RequestTracker控制Reqeust的开始、暂停等
- RequestTracker,控制Reqeust的开始、暂停等
- Request,对应着每一个图片请求
数据处理的类型
- Model:输入类型,例如请求的url、某个图片文件、资源drawableId等等。可以参考Engine的构造函数中,Registry#append(...)添加的类型。
- Data/DataClass:数据源返回的类型,例如InputStream、ParcelFileDescriptor、File、ByteBuffer等。可以参考Engine的构造函数中,Registry#append(...)添加的类型。
- Resource/ResourceType/TResource:中间类型,从数据源返回的类型Data编码成的类型,例如Bitmap、Drawable、GifDrawable、BitmapDrawable、File等。举个例子:例如由InputStream编码成Bitmap。可以参考Engine的构造函数中,Registry#append(...)添加的类型。
- transcode:最终返回的类型。从Resource转换成的类型,例如BitmapDrawable、byte[]。举个例子:由Bitmap转换成BitmapDrawable、由Bitmap转换成byte[]。可以参考Engine的构造函数中,Registry#register(...)添加的类型。
从使用方法作为入口进行分析:
Glide.with(activity)
.load(url)
.into(targetView);
Glide
Glide,是全局唯一的,当我们调用Glide#get(context)时,会去判断是否已经实例化,没有的话会实例化。
// Glide.java
public static RequestManager with(@NonNull View view) {
return getRetriever(view.getContext()).get(view);
}
@NonNull
private static RequestManagerRetriever getRetriever(@Nullable Context context) {
...
return Glide.get(context).getRequestManagerRetriever();
}
public static Glide get(@NonNull Context context) {
if (glide == null) {
// 获取@GlideModule生成的GeneratedAppGlideModuleImpl类
GeneratedAppGlideModule annotationGeneratedModule =
getAnnotationGeneratedGlideModules(context.getApplicationContext());
synchronized (Glide.class) {
if (glide == null) {
// 实例化Glide
checkAndInitializeGlide(context, annotationGeneratedModule);
}
}
}
return glide;
}
private static void checkAndInitializeGlide(
@NonNull Context context, @Nullable GeneratedAppGlideModule generatedAppGlideModule) {
if (isInitializing) {
throw new IllegalStateException(
"...");
}
isInitializing = true;
initializeGlide(context, generatedAppGlideModule);
isInitializing = false;
}
private static void initializeGlide(
@NonNull Context context, @Nullable GeneratedAppGlideModule generatedAppGlideModule) {
initializeGlide(context, new GlideBuilder(), generatedAppGlideModule);
}
private static void initializeGlide(
@NonNull Context context,
@NonNull GlideBuilder builder,
@Nullable GeneratedAppGlideModule annotationGeneratedModule) {
Context applicationContext = context.getApplicationContext();
List<com.bumptech.glide.module.GlideModule> manifestModules = Collections.emptyList();
if (annotationGeneratedModule == null || annotationGeneratedModule.isManifestParsingEnabled()) {
// 解析Manifest中注册的自定义的GlideModule
manifestModules = new ManifestParser(applicationContext).parse();
}
// ... 省略一些GlideModule和log相关的代码
RequestManagerRetriever.RequestManagerFactory factory =
annotationGeneratedModule != null
? annotationGeneratedModule.getRequestManagerFactory()
: null;
// 设置RequestManagerFactory,后面用于创建RequestManager
// 如果没有@GlideModule生成的GeneratedAppGlideModuleImpl类,即factory为null,则使用RequestManagerRetriever类中的一个默认Factory
builder.setRequestManagerFactory(factory);
// ... 省略应用GlideModule相关代码
Glide glide = builder.build(applicationContext);
// ... 省略应用GlideModule相关代码
Glide.glide = glide;
}
Glide(
@NonNull Context context,
@NonNull Engine engine,
@NonNull MemoryCache memoryCache,
@NonNull BitmapPool bitmapPool,
@NonNull ArrayPool arrayPool,
@NonNull RequestManagerRetriever requestManagerRetriever,
@NonNull ConnectivityMonitorFactory connectivityMonitorFactory,
int logLevel,
@NonNull RequestOptionsFactory defaultRequestOptionsFactory,
@NonNull Map<Class<?>, TransitionOptions<?, ?>> defaultTransitionOptions,
@NonNull List<RequestListener<Object>> defaultRequestListeners,
boolean isLoggingRequestOriginsEnabled,
boolean isImageDecoderEnabledForBitmaps) {
this.engine = engine;
// bitmap对象池
this.bitmapPool = bitmapPool;
// 数组对象池
this.arrayPool = arrayPool;
// 默认是LruResourceCache
this.memoryCache = memoryCache;
// 用于根据参数(Application、Activity、FragmentActivity、Fragment、View)获取RequestManager,详见RequestManagerRetriever章节
this.requestManagerRetriever = requestManagerRetriever;
// 内置了一系列的Entry,包含了ModelClass、DataClass、TransocdeClass、Encoder、Decoder、Transcoder等
registry = new Registry();
// Decoder
ResourceDecoder<ByteBuffer, Bitmap> byteBufferBitmapDecoder;
ResourceDecoder<InputStream, Bitmap> streamBitmapDecoder;
if (isImageDecoderEnabledForBitmaps && Build.VERSION.SDK_INT >= Build.VERSION_CODES.P) {
streamBitmapDecoder = new InputStreamBitmapImageDecoderResourceDecoder();
byteBufferBitmapDecoder = new ByteBufferBitmapImageDecoderResourceDecoder();
} else {
byteBufferBitmapDecoder = new ByteBufferBitmapDecoder(downsampler);
streamBitmapDecoder = new StreamBitmapDecoder(downsampler, arrayPool);
}
// 创建ModelLoader的Factory,这里的StreamFactory创建的的是ModelLoader的子类ResourceLoader
ResourceLoader.StreamFactory resourceLoaderStreamFactory =
new ResourceLoader.StreamFactory(resources);
// Transcoder
BitmapBytesTranscoder bitmapBytesTranscoder = new BitmapBytesTranscoder();
// 注册Encoder
registry
.append(ByteBuffer.class, new ByteBufferEncoder())
.append(InputStream.class, new StreamEncoder(arrayPool));
// 注册Decoder
registry.append(Registry.BUCKET_BITMAP, ByteBuffer.class, Bitmap.class, byteBufferBitmapDecoder);
// 注册创建ModelLoader的Factory
registry
.append(int.class, InputStream.class, resourceLoaderStreamFactory)
...
// 根据TranscodeClass创建ImageViewTarget的工厂类
ImageViewTargetFactory imageViewTargetFactory = new ImageViewTargetFactory();
// 用于之后获取Registry等对象
glideContext =
new GlideContext(
context,
arrayPool,
registry,
imageViewTargetFactory,
defaultRequestOptionsFactory,
defaultTransitionOptions,
defaultRequestListeners,
engine,
isLoggingRequestOriginsEnabled,
logLevel);
}
// GlideBuilder.java
Glide build(@NonNull Context context) {
...
// 用来获取RequestManager对象(内部使用RequestManagerFactory创建RequestManager)
RequestManagerRetriever requestManagerRetriever =
new RequestManagerRetriever(requestManagerFactory);
...
return new Glide(
context,
engine,
memoryCache,
bitmapPool,
arrayPool,
requestManagerRetriever,
connectivityMonitorFactory,
logLevel,
defaultRequestOptionsFactory,
defaultTransitionOptions,
defaultRequestListeners,
isLoggingRequestOriginsEnabled,
isImageDecoderEnabledForBitmaps);
}