Glide源码解析05-onLoadComplete

阳光穿透心脏的1/2处 2023-10-17 13:07 105阅读 0赞

## Glide源码解析05-onLoadComplete ##

在Glide源码解析03中我们以及看到Glide调用了EngineRunnable\#onLoadFailed或者EngineRunnable\#onLoadComplete来调用失败或成功的结果。  
这里我们来详细看下onLoadComplete，onLoadFailed也是同样的逻辑。

if (resource == null) {
            onLoadFailed(exception);
        } else {
            onLoadComplete(resource);
        }

##### 5.0 Handler.obtainMessage(MSG\_COMPLETE) #####

在onLoadComplete中调用了EngineRunnableManager\#onResourceReady()，其内部调用Handler发送了MSG\_COMPLETE的消息。

public void onResourceReady(final Resource<?> resource) {
        this.resource = resource;
        MAIN_THREAD_HANDLER.obtainMessage(MSG_COMPLETE, this).sendToTarget();
    }

##### 5.1 Handler.handleMessage #####

在handleMessage中，调用了EngineJob\#handleResultOnMainThread()

public boolean handleMessage(Message message) {
        if (MSG_COMPLETE == message.what || MSG_EXCEPTION == message.what) {
            EngineJob job = (EngineJob) message.obj;
            if (MSG_COMPLETE == message.what) {
                job.handleResultOnMainThread();
            } else {
                job.handleExceptionOnMainThread();
            }
            return true;
        }
    
        return false;
    }

##### 5.2 EngineJob\#handleResultOnMainThread #####

在这里，会去遍历ResourceCallback集合，并调用其onResourceReady()，这里的cb是GenericRequest对象。

private void handleResultOnMainThread() {
        //...
    
        for (ResourceCallback cb : cbs) {
            if (!isInIgnoredCallbacks(cb)) {
                engineResource.acquire();
                cb.onResourceReady(engineResource);
            }
        }
        //...
    }

##### 5.3 GenericRequest\#onResourceReady \#\#\#\# #####

在这里会去调用target\#onResourceReady()，target可以是ImageViewTarget的子类GlideDrawableImageViewTarget、DrawableImageViewTarget、BitmapImageViewTarget。  
具体构建的地方在Glide电泳into方法时，使用ImageViewTargetFactory.buildTarget创建的target对象。

public void onResourceReady(Resource<?> resource) {
        //...
        onResourceReady(resource, (R) received);
    }
    
    private void onResourceReady(Resource<?> resource, R result) {
        boolean isFirstResource = isFirstReadyResource();
        status = Status.COMPLETE;
        this.resource = resource;
    
        if (requestListener == null || !requestListener.onResourceReady(result, model, target, loadedFromMemoryCache,
                isFirstResource)) {
            GlideAnimation<R> animation = animationFactory.build(loadedFromMemoryCache, isFirstResource);
            target.onResourceReady(result, animation);
        }
    
        notifyLoadSuccess();
        //...
    }

##### 5.4 ImageViewTarget\#onResourceReady #####

ImageViewTarget的子类，调用onResourceReady时，最终都会调用setResource()，比如DrawableImageViewTarget

public class DrawableImageViewTarget extends ImageViewTarget<Drawable> {
        public DrawableImageViewTarget(ImageView view) {
            super(view); //父类调用了setResource方法
        }
    
        @Override
        protected void setResource(Drawable resource) {
           view.setImageDrawable(resource);
        }
    }

至此，图片加载成功。

##### PS:cb.onResourceReady #####

在5.2中，调用的cb.onResourceReady，cb为什么是GenericRequest对象对象呢? 这要看调用GenericRequest\#onSizeReady()的时候

//GenericRequest#onSizeReady()
    public void onSizeReady(int width, int height) {
        //...
        loadStatus = engine.load(signature, width, height, dataFetcher, loadProvider, transformation, transcoder,
                priority, isMemoryCacheable, diskCacheStrategy, this);
        loadedFromMemoryCache = resource != null;
        //...
    }
    
    //Engine#load()  
    public <T, Z, R> LoadStatus load(Key signature, int width, int height, DataFetcher<T> fetcher,
            DataLoadProvider<T, Z> loadProvider, Transformation<Z> transformation, ResourceTranscoder<Z, R> transcoder,
            Priority priority, boolean isMemoryCacheable, DiskCacheStrategy diskCacheStrategy, ResourceCallback cb) {
        //...
    
        EngineJob engineJob = engineJobFactory.build(key, isMemoryCacheable);
        //...
        EngineRunnable runnable = new EngineRunnable(engineJob, decodeJob, priority);
        jobs.put(key, engineJob);
    
        //将cb添加到EngineJob中，而cb就是GenericRequest调用engine.load时传入的this参数。
        engineJob.addCallback(cb);
        engineJob.start(runnable);
    
        return new LoadStatus(cb, engineJob);
    }

#### 更多 ####

[Glide源码解析01-with][Glide_01-with]  
[Glide源码解析02-load][Glide_02-load]  
[Glide源码解析03-into][Glide_03-into]  
[ Glide源码解析04-decode][Glide_04-decode]  
[Glide源码解析05-onLoadComplete][Glide_05-onLoadComplete]  
[Glide源码解析06-Glide流程图][Glide_06-Glide]

[Glide_01-with]: http://blog.csdn.net/ethanco/article/details/71977252
[Glide_02-load]: http://blog.csdn.net/ethanco/article/details/71983310
[Glide_03-into]: http://blog.csdn.net/ethanco/article/details/72085582
[Glide_04-decode]: http://blog.csdn.net/ethanco/article/details/72085588
[Glide_05-onLoadComplete]: http://blog.csdn.net/ethanco/article/details/72085605
[Glide_06-Glide]: http://blog.csdn.net/ethanco/article/details/72085606