用法

1
Glide.with(-).load(-).into(-);

With()

Glide.with()方法有较多的重载,但是RequestManagerRetriever.get()获取RequestManagerRetriever,然后再调用相应的get()方法.

Glide.with()

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public static RequestManager with(Context context) {
    RequestManagerRetriever retriever = RequestManagerRetriever.get();
    return retriever.get(context);
}
public static RequestManager with(Activity activity) {
    RequestManagerRetriever retriever = RequestManagerRetriever.get();
    return retriever.get(activity);
}

public static RequestManager with(FragmentActivity activity) {
    RequestManagerRetriever retriever = RequestManagerRetriever.get();
    return retriever.get(activity);
}

@TargetApi(Build.VERSION_CODES.HONEYCOMB)
public static RequestManager with(android.app.Fragment fragment) {
    RequestManagerRetriever retriever = RequestManagerRetriever.get();
    return retriever.get(fragment);
}

public static RequestManager with(Fragment fragment) {
    RequestManagerRetriever retriever = RequestManagerRetriever.get();
    return retriever.get(fragment);
}

retriever.get()

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public RequestManager get(Context context) {
    if (context == null) {
        throw new IllegalArgumentException("You cannot start a load on a null Context");
    } else if (Util.isOnMainThread() && !(context instanceof Application)) {
        if (context instanceof FragmentActivity) {
            return get((FragmentActivity) context);
        } else if (context instanceof Activity) {
            return get((Activity) context);
        } else if (context instanceof ContextWrapper) {
            return get(((ContextWrapper) context).getBaseContext());
        }
    }

    return getApplicationManager(context);
}

public RequestManager get(FragmentActivity activity) {
    if (Util.isOnBackgroundThread()) {
        return get(activity.getApplicationContext());
    } else {
        assertNotDestroyed(activity);
        FragmentManager fm = activity.getSupportFragmentManager();
        return supportFragmentGet(activity, fm);
    }
}

public RequestManager get(Fragment fragment) {
    if (fragment.getActivity() == null) {
        throw new IllegalArgumentException("You cannot start a load on a fragment before it is attached");
    }
    if (Util.isOnBackgroundThread()) {
        return get(fragment.getActivity().getApplicationContext());
    } else {
        FragmentManager fm = fragment.getChildFragmentManager();
        return supportFragmentGet(fragment.getActivity(), fm);
    }
}

@TargetApi(Build.VERSION_CODES.HONEYCOMB)
public RequestManager get(Activity activity) {
    if (Util.isOnBackgroundThread() || Build.VERSION.SDK_INT < Build.VERSION_CODES.HONEYCOMB) {
        return get(activity.getApplicationContext());
    } else {
        assertNotDestroyed(activity);
        android.app.FragmentManager fm = activity.getFragmentManager();
        return fragmentGet(activity, fm);
    }
}

@TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1)
private static void assertNotDestroyed(Activity activity) {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1 && activity.isDestroyed()) {
        throw new IllegalArgumentException("You cannot start a load for a destroyed activity");
    }
}

@TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1)
public RequestManager get(android.app.Fragment fragment) {
    if (fragment.getActivity() == null) {
        throw new IllegalArgumentException("You cannot start a load on a fragment before it is attached");
    }
    if (Util.isOnBackgroundThread() || Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN_MR1) {
        return get(fragment.getActivity().getApplicationContext());
    } else {
        android.app.FragmentManager fm = fragment.getChildFragmentManager();
        return fragmentGet(fragment.getActivity(), fm);
    }
}
//app包下获取一个透明的fragment
@TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1)
RequestManagerFragment getRequestManagerFragment(final android.app.FragmentManager fm) {
    RequestManagerFragment current = (RequestManagerFragment) fm.findFragmentByTag(FRAGMENT_TAG);
    if (current == null) {
        current = pendingRequestManagerFragments.get(fm);
        if (current == null) {
          //透明的fragment
            current = new RequestManagerFragment();
            pendingRequestManagerFragments.put(fm, current);
            fm.beginTransaction().add(current, FRAGMENT_TAG).commitAllowingStateLoss();
            handler.obtainMessage(ID_REMOVE_FRAGMENT_MANAGER, fm).sendToTarget();
        }
    }
    return current;
}
//app包下requestManager
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
RequestManager fragmentGet(Context context, android.app.FragmentManager fm) {
    RequestManagerFragment current = getRequestManagerFragment(fm);
    RequestManager requestManager = current.getRequestManager();
    if (requestManager == null) {
        requestManager = new RequestManager(context, current.getLifecycle(), current.getRequestManagerTreeNode());
        current.setRequestManager(requestManager);
    }
    return requestManager;
}
//V4包下获取一个透明的fragment
SupportRequestManagerFragment getSupportRequestManagerFragment(final FragmentManager fm) {
    SupportRequestManagerFragment current = (SupportRequestManagerFragment) fm.findFragmentByTag(


        FRAGMENT_TAG);
    if (current == null) {
        current = pendingSupportRequestManagerFragments.get(fm);
//透明的fragment
        if (current == null) {
            current = new SupportRequestManagerFragment();
            pendingSupportRequestManagerFragments.put(fm, current);
            fm.beginTransaction().add(current, FRAGMENT_TAG).commitAllowingStateLoss();
            handler.obtainMessage(ID_REMOVE_SUPPORT_FRAGMENT_MANAGER, fm).sendToTarget();
        }
    }
    return current;
}

//V4包下requestManager
RequestManager supportFragmentGet(Context context, FragmentManager fm) {
    SupportRequestManagerFragment current = getSupportRequestManagerFragment(fm);
    RequestManager requestManager = current.getRequestManager();
    if (requestManager == null) {
        requestManager = new RequestManager(context, current.getLifecycle(), current.getRequestManagerTreeNode());
        current.setRequestManager(requestManager);
    }
    return requestManager;
}

代码比较复杂,实际上是判断了为Application的Context还是非Application的Context(非UI线程直接当做Application的处理).在非Application的情况下又分为v4包和app包两种情况(因为现在都基本不怎么使用app包下的这个了,所以下面不单独分析).

参数为非Application的情况下,会向当前的Activity当中添加一个隐藏的Fragment.Glide就使用了添加隐藏Fragment的这种小技巧(因为Fragment的生命周期和Activity是同步的，如果Activity被销毁了，Fragment是可以监听到的)这样Glide就可以监听到销毁事件并停止图片加载了。

Application情况下获得一个与ApplicationLifecycle绑定的requestManager

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private RequestManager getApplicationManager(Context context) {
    // Either an application context or we're on a background thread.
    if (applicationManager == null) {
        synchronized (this) {
            if (applicationManager == null) {
                // Normally pause/resume is taken care of by the fragment we add to the fragment or activity.
                // However, in this case since the manager attached to the application will not receive lifecycle
                // events, we must force the manager to start resumed using ApplicationLifecycle.
                applicationManager = new RequestManager(context.getApplicationContext(),
                        new ApplicationLifecycle(), new EmptyRequestManagerTreeNode());
            }
        }
    }
    return applicationManager;
}

Glide.with()方法得到了RequestManager,并且确定了图片的加载生命周期.

load()