android 广播机制(1) 注册广播

源码路径:/frameworks/base/core/java/android/app/ContextImpl.java

  @Override    public Intent registerReceiver(BroadcastReceiver receiver, IntentFilter filter) {        return registerReceiver(receiver, filter, null, null);    }    @Override    public Intent registerReceiver(BroadcastReceiver receiver, IntentFilter filter,            String broadcastPermission, Handler scheduler) {        return registerReceiverInternal(receiver, getUserId(),                filter, broadcastPermission, scheduler, getOuterContext());    }    @Override    public Intent registerReceiverAsUser(BroadcastReceiver receiver, UserHandle user,            IntentFilter filter, String broadcastPermission, Handler scheduler) {        return registerReceiverInternal(receiver, user.getIdentifier(),                filter, broadcastPermission, scheduler, getOuterContext());    }    private Intent registerReceiverInternal(BroadcastReceiver receiver, int userId,            IntentFilter filter, String broadcastPermission,            Handler scheduler, Context context) {        IIntentReceiver rd = null;        if (receiver != null) {            if (mPackageInfo != null && context != null) {                if (scheduler == null) {                    scheduler = mMainThread.getHandler();                }                rd = mPackageInfo.getReceiverDispatcher(                    receiver, context, scheduler,                    mMainThread.getInstrumentation(), true);            } else {                if (scheduler == null) {                    scheduler = mMainThread.getHandler();                }                rd = new LoadedApk.ReceiverDispatcher(                        receiver, context, scheduler, null, true).getIIntentReceiver();            }        }        try {            return ActivityManagerNative.getDefault().registerReceiver(                    mMainThread.getApplicationThread(), mBasePackageName,                    rd, filter, broadcastPermission, userId);        } catch (RemoteException e) {            return null;        }    }

最后会进入到ActivityManagerService，就是说一个应用的广播要注册到AMS中去管理
源码路径:xref: /frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java

 public Intent registerReceiver(IApplicationThread caller, String callerPackage,            IIntentReceiver receiver, IntentFilter filter, String permission, int userId) {        enforceNotIsolatedCaller("registerReceiver");        ArrayList stickyIntents = null;  //粘性广播        ProcessRecord callerApp = null;        int callingUid;        int callingPid;        synchronized(this) {            if (caller != null) { //正常caller不为null，是一个应用                callerApp = getRecordForAppLocked(caller);   //获取注册广播的应用                if (callerApp == null) {     //应用不存在                    throw new SecurityException(                            "Unable to find app for caller " + caller                            + " (pid=" + Binder.getCallingPid()                            + ") when registering receiver " + receiver);                }                if (callerApp.info.uid != Process.SYSTEM_UID &&                        !callerApp.pkgList.containsKey(callerPackage) &&                        !"android".equals(callerPackage)) {    //应用不包含这个包名                    throw new SecurityException("Given caller package " + callerPackage                            + " is not running in process " + callerApp);                }                callingUid = callerApp.info.uid; //应用uid                callingPid = callerApp.pid;  //应用pid            } else {                callerPackage = null;                callingUid = Binder.getCallingUid();                callingPid = Binder.getCallingPid();            }            userId = handleIncomingUser(callingPid, callingUid, userId,                    true, ALLOW_FULL_ONLY, "registerReceiver", callerPackage);    //用户id            Iterator actions = filter.actionsIterator();            if (actions == null) {                ArrayList noAction = new ArrayList(1);                noAction.add(null);                actions = noAction.iterator();            }            // Collect stickies of users            int[] userIds = { UserHandle.USER_ALL, UserHandle.getUserId(callingUid) };            while (actions.hasNext()) {                String action = actions.next();                for (int id : userIds) {                    ArrayMap> stickies = mStickyBroadcasts.get(id);                    if (stickies != null) {                        ArrayList intents = stickies.get(action);  //获取是否有这个action的intent                        if (intents != null) {                            if (stickyIntents == null) {                                stickyIntents = new ArrayList();     //增加stickyIntents                            }                            stickyIntents.addAll(intents);                        }                    }                }            }        }        ArrayList allSticky = null;        if (stickyIntents != null) {            final ContentResolver resolver = mContext.getContentResolver();            // Look for any matching sticky broadcasts...            for (int i = 0, N = stickyIntents.size(); i < N; i++) {                Intent intent = stickyIntents.get(i);                // If intent has scheme "content", it will need to acccess                // provider that needs to lock mProviderMap in ActivityThread                // and also it may need to wait application response, so we                // cannot lock ActivityManagerService here.                if (filter.match(resolver, intent, true, TAG) >= 0) {                    if (allSticky == null) {                        allSticky = new ArrayList();                    }                    allSticky.add(intent); //所有粘性广播生成                }            }        }        // The first sticky in the list is returned directly back to the client.        Intent sticky = allSticky != null ? allSticky.get(0) : null;    //第一个粘性广播马上返回给客户端        if (DEBUG_BROADCAST) Slog.v(TAG_BROADCAST, "Register receiver " + filter + ": " + sticky);        if (receiver == null) {            return sticky;        }        synchronized (this) {            if (callerApp != null && (callerApp.thread == null                    || callerApp.thread.asBinder() != caller.asBinder())) {                // Original caller already died    //应用死掉了                return null;            }            ReceiverList rl = mRegisteredReceivers.get(receiver.asBinder());            if (rl == null) {                rl = new ReceiverList(this, callerApp, callingPid, callingUid,                        userId, receiver);                if (rl.app != null) {                    rl.app.receivers.add(rl);                } else {                    try {                        receiver.asBinder().linkToDeath(rl, 0);                    } catch (RemoteException e) {                        return sticky;                    }                    rl.linkedToDeath = true;                }                mRegisteredReceivers.put(receiver.asBinder(), rl);   //生成mRegisteredReceivers            } else if (rl.uid != callingUid) {                throw new IllegalArgumentException(                        "Receiver requested to register for uid " + callingUid                        + " was previously registered for uid " + rl.uid);            } else if (rl.pid != callingPid) {                throw new IllegalArgumentException(                        "Receiver requested to register for pid " + callingPid                        + " was previously registered for pid " + rl.pid);            } else if (rl.userId != userId) {                throw new IllegalArgumentException(                        "Receiver requested to register for user " + userId                        + " was previously registered for user " + rl.userId);            }            BroadcastFilter bf = new BroadcastFilter(filter, rl, callerPackage,                    permission, callingUid, userId);            rl.add(bf);            //ReceiverList rl保存的是intent的数组，例如一个广播接收器可以注册两个intent 过滤条件            if (!bf.debugCheck()) {                Slog.w(TAG, "==> For Dynamic broadcast");            }            mReceiverResolver.addFilter(bf);       //生成mReceiverResolver            // Enqueue broadcasts for all existing stickies that match            // this filter.            if (allSticky != null) {                ArrayList receivers = new ArrayList();                receivers.add(bf);                final int stickyCount = allSticky.size();                for (int i = 0; i < stickyCount; i++) {                    Intent intent = allSticky.get(i);   //处理粘性广播                    BroadcastQueue queue = broadcastQueueForIntent(intent);                    BroadcastRecord r = new BroadcastRecord(queue, intent, null,                            null, -1, -1, null, null, AppOpsManager.OP_NONE, null, receivers,                            null, 0, null, null, false, true, true, -1);                    queue.enqueueParallelBroadcastLocked(r);                    queue.scheduleBroadcastsLocked();                }            }            return sticky;        }    }

所以注册广播，最后生成了什么东西了？
1.粘性广播处理
2.生成变量mRegisteredReceivers，里面保存了所有广播，mRegisteredReceivers已应用token为key值，intent数组为值

class ReceiverList extends ArrayList

3.生成mReceiverResolver，里面保存着intent

public abstract class IntentResolver

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