Broadcast 分析之 sendBroadcast_broadcastintentwithcallback-优快云博客

本文链接：https://blog.youkuaiyun.com/wg_mlo/article/details/123430870

本文详细探讨了Broadcast的sendBroadcast方法，从ContextImpl的调用开始，涉及系统广播处理、粘性广播处理和平行广播（有序广播）的处理流程。重点分析了平行广播的入队和处理，通过BroadcastHandler进行消息调度，并阐述了如何在ApplicationThread中通过Binder进行本地进程回调，最终执行到BroadcastReceiver的onReceive方法。

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Broadcast 分析之 sendBroadcast

// frameworks/base/core/java/android/content/ContextWrapper.java
@Override
public void sendBroadcast(Intent intent) {
   
   
    mBase.sendBroadcast(intent);
}

// frameworks/base/core/java/android/content/Context.java
public abstract void sendBroadcast(@RequiresPermission Intent intent);

最后都会调用到 ContextImpl

// frameworks/base/core/java/android/app/ContextImpl.java
@Override
public void sendBroadcast(Intent intent) {
   
   
    warnIfCallingFromSystemProcess();
    String resolvedType = intent.resolveTypeIfNeeded(getContentResolver());
    try {
   
   
        // 预处理
        intent.prepareToLeaveProcess(this);
        // 跨进程通信 AMS.broadcastIntentWithFeature
        ActivityManager.getService().broadcastIntentWithFeature(
            mMainThread.getApplicationThread(), getAttributionTag(), intent, resolvedType,
            null, Activity.RESULT_OK, null, null, null, AppOpsManager.OP_NONE, null, false,
            false, getUserId());
    } catch (RemoteException e) {
   
   
        throw e.rethrowFromSystemServer();
    }
}

// frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java
public final int broadcastIntentWithFeature(IApplicationThread caller, String 		 		callingFeatureId,Intent intent, String resolvedType, IIntentReceiver resultTo,int resultCode, String resultData, Bundle resultExtras,String[] requiredPermissions, int appOp, Bundle bOptions, boolean serialized, boolean sticky, int userId) {
   
   
    enforceNotIsolatedCaller("broadcastIntent");
    synchronized(this) {
   
   
        intent = verifyBroadcastLocked(intent);

        final ProcessRecord callerApp = getRecordForAppLocked(caller);
        final int callingPid = Binder.getCallingPid();
        final int callingUid = Binder.getCallingUid();
        final long origId = Binder.clearCallingIdentity();
        try {
   
   
            return broadcastIntentLocked(callerApp,callerApp != null ? callerApp.info.packageName : null, callingFeatureId,intent, resolvedType, resultTo, resultCode, resultData, resultExtras,requiredPermissions, appOp, bOptions, serialized, sticky,callingPid, callingUid, callingUid, callingPid, userId);
        } finally {
   
   
            Binder.restoreCallingIdentity(origId);
        }
    }
}

@GuardedBy("this")
final int broadcastIntentLocked(ProcessRecord callerApp,
        String callerPackage, String callerFeatureId, Intent intent, String resolvedType,
        IIntentReceiver resultTo, int resultCode, String resultData,
        Bundle resultExtras, String[] requiredPermissions, int appOp, Bundle bOptions,
        boolean ordered, boolean sticky, int callingPid, int callingUid, int realCallingUid,
        int realCallingPid, int userId) {
   
   
    return broadcastIntentLocked(callerApp, callerPackage, callerFeatureId, intent,
            resolvedType, resultTo, resultCode, resultData, resultExtras, requiredPermissions,
            appOp, bOptions, ordered, sticky, callingPid, callingUid, realCallingUid,
            realCallingPid, userId, false /* allowBackgroundActivityStarts */,
            null /*broadcastWhitelist*/);
}

系统广播处理
粘性广播处理
平行广播处理 (以下分析)
有序广播处理
记录无人注册的其他广播

@GuardedBy("this")
final int broadcastIntentLocked(ProcessRecord callerApp, String callerPackage,
                                @Nullable String callerFeatureId, Intent intent, String resolvedType,IIntentReceiver resultTo, int resultCode, String resultData,Bundle