Broadcast相关的数据结构

1. Broadcast数据结构

broadcast.png

2. BroadcastRecord

BroadcastRecord在AMS中表示一个广播的信息
ProcessRecord callerApp : 发送广播进程的信息
boolean ordered ：是否是有序广播
boolean sticky：是否是粘性广播
List receivers：广播接收器，包括动态注册(BroadcastFilter)和静态注册(ResolveInfo)
IBinder receiver：Binder代理段，对应应用进程中的IIntentReceiver

3. LoadedApk

在应用进程注册BroadcastReceiver的时候，会将BroadcastReceiver保存到LoadedApk的mReceivers中，同时为当前的BroadcastRecevier生成一个对应的ReceiverDispatcher, ReceiverDispatcher中有一个IIntentReceiver对象，是Binder的服务端，然后将这个Binder类型传递给了AMS,AMS持有代理端，也就是BroadcastRecord中的Binder receiver对象.

BroadcastRecevier -- ReceiverDispatcher -- IIntentReceiver -- BroadcastRecord是一一对应的。

4. AMS的mStickyBroadcasts

    /**
     * State of all active sticky broadcasts per user.  Keys are the action of the
     * sticky Intent, values are an ArrayList of all broadcasted intents with
     * that action (which should usually be one).  The SparseArray is keyed
     * by the user ID the sticky is for, and can include UserHandle.USER_ALL
     * for stickies that are sent to all users.
     */
    final SparseArray<ArrayMap<String, ArrayList<Intent>>> mStickyBroadcasts =
            new SparseArray<ArrayMap<String, ArrayList<Intent>>>();

mStickyBroadcasts 首先是以userID为key，保存了每个用户下的粘性广播 ArrayMap<String, ArrayList<Intent>>
而每个用户下的粘性广播又是以String类型的Action为key，保存对应的intent的列表. 同一个Action可能会发多次广播. 每次广播是一个intent对象
mStickyBroadcasts 用来保存系统中发送的所有的sticky broadcast， 每当系统中发送一次sticky broadcast, 都会保存到该容器中.

当有进程广播注册的时候，如果注册了对应类型的Action广播，会立刻收到对应的粘性广播

5. AMS的mRegisteredReceivers

    /**
     * Keeps track of all IIntentReceivers that have been registered for broadcasts.
     * Hash keys are the receiver IBinder, hash value is a ReceiverList.
     */
    final HashMap<IBinder, ReceiverList> mRegisteredReceivers = new HashMap<>();

保存了系统中所有的动态注册的广播，以应用进程中的IIntentReceiver的binder代理端为key, 保存了该Receiver对应的所有IntentFilter，是一个一对多的关系，一个BroadcastReceiver对应多个intentFilter。

ReceiverList继承了ArrayList<BroadcastFilter>, 保存一个BroadcastReceiver对应的IIntentReceiver以及多个BroadcastFilter，一个BroadcastFilter对应一个IntentFilter。

对应关系.png

每次注册都会向对应IIntentReceiver所在的ReceiverList列表中添加一个BroadcastFilter

只有registerReceiver()过程才会创建BroadcastFilter,也就是该对象用于动态注册的广播Receiver;

BroadcastFilter继承于IntentFilter.同样地, 只有registerReceiver()过程才会创建ReceiverList;

6. ProcessRecord的receivers

    // all IIntentReceivers that are registered from this process.
    final ArraySet<ReceiverList> receivers = new ArraySet<>();

receivers中保存了当前进程所有动态注册的广播接收者

7. BroadcastQueue

    ArrayList<BroadcastRecord> mParallelBroadcasts = new ArrayList<>()

保存了将要发送的 非有序 动态注册的广播

ArrayList<BroadcastRecord> mOrderedBroadcasts = new ArrayList<>()

保存了将要发送的静态注册的广播和有序广播