glide4核心流程梳理

基本使用

https://github.com/bumptech/glide
1.简单使用：Glide.with(this).load("http://goo.gl/gEgYUd").into(imageView);
2.进阶使用：RequestOptions sharedOptions =  new RequestOptions().placeholder(placeholder).fitCenter();
Glide.with(fragment).load(myUrl).apply(sharedOptions).into(imageView1);

一、with 初始化glide

public static RequestManager with(@NonNull Context context) {
  return getRetriever(context).get(context);
}

private static RequestManagerRetriever getRetriever(@Nullable Context context) {
  return Glide.get(context).getRequestManagerRetriever();
}

public static Glide get(@NonNull Context context) {
  if (glide == null) {
   //1、获取应用中带注解的GlideModule
    GeneratedAppGlideModule annotationGeneratedModule =
        getAnnotationGeneratedGlideModules(context.getApplicationContext());
    synchronized (Glide.class) { 
      if (glide == null) { //2.双重检测安全初始化
        checkAndInitializeGlide(context, annotationGeneratedModule);
      }
    }
  }
  return glide;
}

private static GeneratedAppGlideModule getAnnotationGeneratedGlideModules(Context context) {
    GeneratedAppGlideModule result = null;
    try {
      Class clazz = (Class)
              Class.forName("com.bumptech.glide.GeneratedAppGlideModuleImpl");
      result = clazz.getDeclaredConstructor(Context.class).newInstance(context.getApplicationContext());
    } catch (ClassNotFoundException e) {
      ...
    }
    return result;
  }

 private static void initializeGlide(
      @NonNull Context context,
      @NonNull GlideBuilder builder,
      @Nullable GeneratedAppGlideModule annotationGeneratedModule) {
    Context applicationContext = context.getApplicationContext();
    // 2、如果GlideModule为空或者可配置manifest里面的标志为true，则获取manifest里面 配置的GlideModule模块（manifestModules）。
    List manifestModules = Collections.emptyList();
    if (annotationGeneratedModule == null || annotationGeneratedModule.isManifestParsingEnabled()) {
      manifestModules = new ManifestParser(applicationContext).parse();
    }

    if (annotationGeneratedModule != null && !annotationGeneratedModule.getExcludedModuleClasses().isEmpty()) {
      Set> excludedModuleClasses = annotationGeneratedModule.getExcludedModuleClasses();
      Iterator iterator = manifestModules.iterator();
      while (iterator.hasNext()) {
        com.bumptech.glide.module.GlideModule current = iterator.next();
        if (!excludedModuleClasses.contains(current.getClass())) {
          continue;
        }
        iterator.remove();
      }
    }

    RequestManagerRetriever.RequestManagerFactory factory =annotationGeneratedModule != null ? annotationGeneratedModule.getRequestManagerFactory() : null;
    builder.setRequestManagerFactory(factory);
    for (com.bumptech.glide.module.GlideModule module : manifestModules) {
      module.applyOptions(applicationContext, builder);
    }
    if (annotationGeneratedModule != null) {
      annotationGeneratedModule.applyOptions(applicationContext, builder);
    }
    // 3、初始化各种配置信息
    Glide glide = builder.build(applicationContext);
    // 4、把manifestModules以及annotationGeneratedModule里面的配置信息放到builder里面（applyOptions）替换glide默认组件（registerComponents）
    for (com.bumptech.glide.module.GlideModule module : manifestModules) {
      try {
        module.registerComponents(applicationContext, glide, glide.registry);
      } catch (AbstractMethodError e) {
      }
    }
    if (annotationGeneratedModule != null) {
      annotationGeneratedModule.registerComponents(applicationContext, glide, glide.registry);
    }
    applicationContext.registerComponentCallbacks(glide);
    Glide.glide = glide;
  }

public RequestManagerRetriever getRequestManagerRetriever() {
  return requestManagerRetriever;
}

GlideBuilder.build(applicationContext)

  Glide build(@NonNull Context context) {
    if (sourceExecutor == null) { // 创建请求图片线程池sourceExecutor
      sourceExecutor = GlideExecutor.newSourceExecutor();
    }
    if (diskCacheExecutor == null) { // 创建磁盘缓存线程池diskCacheExecutor
      diskCacheExecutor = GlideExecutor.newDiskCacheExecutor();
    }
    if (animationExecutor == null) {// 创建动画线程池animationExecutor
      animationExecutor = GlideExecutor.newAnimationExecutor();
    }
    if (memorySizeCalculator == null) {//内存缓存相关配置
      memorySizeCalculator = new MemorySizeCalculator.Builder(context).build();
    }
    if (connectivityMonitorFactory == null) {
      connectivityMonitorFactory = new DefaultConnectivityMonitorFactory();
    }
    if (bitmapPool == null) {
      int size = memorySizeCalculator.getBitmapPoolSize();// 依据设备的屏幕密度和尺寸设置各种pool的size
      if (size > 0) {
      	// 创建图片线程池LruBitmapPool，缓存所有被释放的bitmap 缓存策略在API大于19时，为SizeConfigStrategy，小于为AttributeStrategy。
        // 其中SizeConfigStrategy是以bitmap的size和config为key，value为bitmap的HashMap
        bitmapPool = new LruBitmapPool(size);
      } else {
        bitmapPool = new BitmapPoolAdapter();
      }
    }

    if (arrayPool == null) {// 创建对象数组缓存池LruArrayPool，默认4M
      arrayPool = new LruArrayPool(memorySizeCalculator.getArrayPoolSizeInBytes());
    }
    if (memoryCache == null) {// 创建LruResourceCache，内存缓存
      memoryCache = new LruResourceCache(memorySizeCalculator.getMemoryCacheSize());
    }
    if (diskCacheFactory == null) {// 创建磁盘缓存工厂
      diskCacheFactory = new InternalCacheDiskCacheFactory(context);
    }

    if (engine == null) {//创建任务和资源管理引擎（线程池，内存缓存和磁盘缓存对象）
      engine =  new Engine(memoryCache,  diskCacheFactory, diskCacheExecutor, sourceExecutor,
              GlideExecutor.newUnlimitedSourceExecutor(),
              animationExecutor,
              isActiveResourceRetentionAllowed);
    }
    if (defaultRequestListeners == null) {
      defaultRequestListeners = Collections.emptyList();
    } else {
      defaultRequestListeners = Collections.unmodifiableList(defaultRequestListeners);
    }
    RequestManagerRetriever requestManagerRetriever = new RequestManagerRetriever(requestManagerFactory);
    return new Glide(
        context,
        engine,
        memoryCache,
        bitmapPool,
        arrayPool,
        requestManagerRetriever,
        connectivityMonitorFactory,
        logLevel,
        defaultRequestOptionsFactory,
        defaultTransitionOptions,
        defaultRequestListeners,
        isLoggingRequestOriginsEnabled,
        isImageDecoderEnabledForBitmaps);
  }

glide构造函数

Glide(...) {
    ...
    // 注册管理任务执行对象的类(Registry) Registry是一个工厂，而其中所有注册的对象都是一个工厂员工，当任务分发时，根据当前任务的性质，分发给相应员工进行处理
    registry = new Registry();
    ...
    // 一系列的append或register工厂组件（解析器、编解码器、工厂类、转码类等等组件）
    registry
    .append(ByteBuffer.class, new ByteBufferEncoder())
    .append(InputStream.class, new StreamEncoder(arrayPool))
    ...
    // 根据给定子类产出对应类型的target（BitmapImageViewTarget / DrawableImageViewTarget)
    ImageViewTargetFactory imageViewTargetFactory = new ImageViewTargetFactory();
   
    glideContext = new GlideContext( context, arrayPool, registry, imageViewTargetFactory,
            defaultRequestOptionsFactory,
            defaultTransitionOptions,
            defaultRequestListeners,
            engine,
            isLoggingRequestOriginsEnabled,
            logLevel);
}

RequestManagerRetriever.get

    if (context == null) {
      throw new IllegalArgumentException("You cannot start a load on a null Context");
    } else if (Util.isOnMainThread() && !(context instanceof Application)) {
     // 如果当前线程是主线程且context不是Application走相应的get重载方法
      if (context instanceof FragmentActivity) {
        return get((FragmentActivity) context);
      } else if (context instanceof Activity) {
        return get((Activity) context);
      } else if (context instanceof ContextWrapper
          && ((ContextWrapper) context).getBaseContext().getApplicationContext() != null) {
        return get(((ContextWrapper) context).getBaseContext());
      }
    }
    // 否则直接将请求与ApplicationLifecycle关联
    return getApplicationManager(context);
  }
  
  //注意如果是FragmentActivity或者fragment最终会创建一个空的fragment来进行生命周期绑定
    public RequestManager get(@NonNull FragmentActivity activity) {
    if (Util.isOnBackgroundThread()) {
      return get(activity.getApplicationContext());
    } else {
      assertNotDestroyed(activity);
      FragmentManager fm = activity.getSupportFragmentManager();
      return supportFragmentGet(activity, fm, /*parentHint=*/ null, isActivityVisible(activity));
    }
  }
  
   @NonNull
  private SupportRequestManagerFragment getSupportRequestManagerFragment(
      @NonNull final FragmentManager fm, @Nullable Fragment parentHint, boolean isParentVisible) {
    SupportRequestManagerFragment current =
        (SupportRequestManagerFragment) fm.findFragmentByTag(FRAGMENT_TAG);
    if (current == null) {
      current = pendingSupportRequestManagerFragments.get(fm);
      if (current == null) {
        current = new SupportRequestManagerFragment();
        current.setParentFragmentHint(parentHint);
        if (isParentVisible) {
          current.getGlideLifecycle().onStart();
        }
        pendingSupportRequestManagerFragments.put(fm, current);
        fm.beginTransaction().add(current, FRAGMENT_TAG).commitAllowingStateLoss();
        handler.obtainMessage(ID_REMOVE_SUPPORT_FRAGMENT_MANAGER, fm).sendToTarget();
      }
    }
    return current;
  }

二、RequestManager.load

// 1、asDrawable部分 2.load
public RequestBuilder load(@Nullable String string) {
    return asDrawable().load(string);
  }
  
public  RequestBuilder as(
      @NonNull Class resourceClass) {
    return new RequestBuilder<>(glide, this, resourceClass, context);
}
    
@NonNull
  private RequestBuilder loadGeneric(@Nullable Object model) {
    this.model = model;// model则为设置的url
    isModelSet = true; // 记录url已设置
    return this;
  }

三、RequestBuilder.into

into的代码涉及太多放一个梳理的流程图
被压缩掉了放一个gitee地址：
http://www.kaotop.com/file/tupian/20220423/Glide4.11.0.png