ps：以下源碼分析基于Glide v4.11.0
Glide.jpg
涉及的類
主要涉及到以下這些類：
- Glide，全局唯一
- RequestManagerRetriever，用于獲取RequestManager
- RequestManagerFragment/SupportRequestManagerFragment，用于提供生命周期
- RequestManager，用于管理Request，內(nèi)部使用RequestTracker控制Reqeust的開始、暫停等
- RequestTracker，控制Reqeust的開始、暫停等
- Request，對(duì)應(yīng)著每一個(gè)圖片請(qǐng)求
數(shù)據(jù)處理的類型
- Model：輸入類型，例如請(qǐng)求的url、某個(gè)圖片文件、資源drawableId等等。可以參考Engine的構(gòu)造函數(shù)中，Registry#append(...)添加的類型。
- Data/DataClass：數(shù)據(jù)源返回的類型，例如InputStream、ParcelFileDescriptor、File、ByteBuffer等。可以參考Engine的構(gòu)造函數(shù)中，Registry#append(...)添加的類型。
- Resource/ResourceType/TResource：中間類型，從數(shù)據(jù)源返回的類型Data編碼成的類型，例如Bitmap、Drawable、GifDrawable、BitmapDrawable、File等。舉個(gè)例子：例如由InputStream編碼成Bitmap。可以參考Engine的構(gòu)造函數(shù)中，Registry#append(...)添加的類型。
- transcode：最終返回的類型。從Resource轉(zhuǎn)換成的類型，例如BitmapDrawable、byte[]。舉個(gè)例子：由Bitmap轉(zhuǎn)換成BitmapDrawable、由Bitmap轉(zhuǎn)換成byte[]。可以參考Engine的構(gòu)造函數(shù)中，Registry#register(...)添加的類型。
從使用方法作為入口進(jìn)行分析：
Glide.with(activity)
.load(url)
.into(targetView);
Glide
Glide，是全局唯一的，當(dāng)我們調(diào)用Glide#get(context)時(shí)，會(huì)去判斷是否已經(jīng)實(shí)例化，沒有的話會(huì)實(shí)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) {
// 獲取@GlideModule生成的GeneratedAppGlideModuleImpl類
GeneratedAppGlideModule annotationGeneratedModule =
getAnnotationGeneratedGlideModules(context.getApplicationContext());
synchronized (Glide.class) {
if (glide == null) {
// 實(shí)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中注冊(cè)的自定義的GlideModule
manifestModules = new ManifestParser(applicationContext).parse();
}
// ... 省略一些GlideModule和log相關(guān)的代碼
RequestManagerRetriever.RequestManagerFactory factory =
annotationGeneratedModule != null
? annotationGeneratedModule.getRequestManagerFactory()
: null;
// 設(shè)置RequestManagerFactory，后面用于創(chuàng)建RequestManager
// 如果沒有@GlideModule生成的GeneratedAppGlideModuleImpl類，即factory為null，則使用RequestManagerRetriever類中的一個(gè)默認(rèn)Factory
builder.setRequestManagerFactory(factory);
// ... 省略應(yīng)用GlideModule相關(guān)代碼
Glide glide = builder.build(applicationContext);
// ... 省略應(yīng)用GlideModule相關(guān)代碼
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對(duì)象池
this.bitmapPool = bitmapPool;
// 數(shù)組對(duì)象池
this.arrayPool = arrayPool;
// 默認(rèn)是LruResourceCache
this.memoryCache = memoryCache;
// 用于根據(jù)參數(shù)（Application、Activity、FragmentActivity、Fragment、View）獲取RequestManager，詳見RequestManagerRetriever章節(jié)
this.requestManagerRetriever = requestManagerRetriever;
// 內(nèi)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);
}
// 創(chuàng)建ModelLoader的Factory，這里的StreamFactory創(chuàng)建的的是ModelLoader的子類ResourceLoader
ResourceLoader.StreamFactory resourceLoaderStreamFactory =
new ResourceLoader.StreamFactory(resources);
// Transcoder
BitmapBytesTranscoder bitmapBytesTranscoder = new BitmapBytesTranscoder();
// 注冊(cè)Encoder
registry
.append(ByteBuffer.class, new ByteBufferEncoder())
.append(InputStream.class, new StreamEncoder(arrayPool));
// 注冊(cè)Decoder
registry.append(Registry.BUCKET_BITMAP, ByteBuffer.class, Bitmap.class, byteBufferBitmapDecoder);
// 注冊(cè)創(chuàng)建ModelLoader的Factory
registry
.append(int.class, InputStream.class, resourceLoaderStreamFactory)
...
// 根據(jù)TranscodeClass創(chuàng)建ImageViewTarget的工廠類
ImageViewTargetFactory imageViewTargetFactory = new ImageViewTargetFactory();
// 用于之后獲取Registry等對(duì)象
glideContext =
new GlideContext(
context,
arrayPool,
registry,
imageViewTargetFactory,
defaultRequestOptionsFactory,
defaultTransitionOptions,
defaultRequestListeners,
engine,
isLoggingRequestOriginsEnabled,
logLevel);
}
// GlideBuilder.java
Glide build(@NonNull Context context) {
...
// 用來獲取RequestManager對(duì)象（內(nèi)部使用RequestManagerFactory創(chuàng)建RequestManager）
RequestManagerRetriever requestManagerRetriever =
new RequestManagerRetriever(requestManagerFactory);
...
return new Glide(
context,
engine,
memoryCache,
bitmapPool,
arrayPool,
requestManagerRetriever,
connectivityMonitorFactory,
logLevel,
defaultRequestOptionsFactory,
defaultTransitionOptions,
defaultRequestListeners,
isLoggingRequestOriginsEnabled,
isImageDecoderEnabledForBitmaps);
}
