本文深入解析了Android系统中广播发送的详细流程，包括广播的发送方式、系统处理过程、广播队列管理及接收者处理逻辑。涉及广播类型如普通、有序、粘性广播及其发送方法，以及AMS如何调度和分发广播给静态与动态注册的接收者。
Android广播发送流程
1. 广播发送流程
这次我们讲一下广播发送的流程，老规矩先上大概的流程图
2. 广播发送
- 常见的通过ContextImpl.java发送广播的方法有下面几种
=> sendBroadcast/sendBroadcastAsUser ：普通的广播发送，默认是当前userId，带有“AsUser”的是发送给特定的user
=> sendBroadcastMultiplePermissions/sendBroadcastAsUserMultiplePermissions ：带有多个权限的广播发送
=> sendOrderedBroadcast/sendOrderedBroadcastAsUser ：发送order有序的广播(order广播是一个接收完成下一个才能接收，接收者一个个按顺序接收)
=> sendStickyBroadcast/sendStickyBroadcastAsUser ：发送粘性广播，粘性广播的意思是注册者注册了就马上能收到该类型(之前已经发送的粘性广播)的广播，
接收者的注册不需要在发送者的前面
=> sendStickyOrderedBroadcast/sendStickyOrderedBroadcastAsUser ：发送粘性而且是顺序order的广播
它们都是调用AMS的broadcastIntentWithFeature来发送广播
如下面是最简单的只有一个Intent的广播发送
//ContextImpl.java
@Override
public void sendBroadcast(Intent intent) {
warnIfCallingFromSystemProcess();
String resolvedType = intent.resolveTypeIfNeeded(getContentResolver());
try {
intent.prepareToLeaveProcess(this);
//调用的是AMS的broadcastIntentWithFeature来发送广播
ActivityManager.getService().broadcastIntentWithFeature(
mMainThread.getApplicationThread(), getAttributionTag(), intent, resolvedType,
null, Activity.RESULT_OK, null, null, null, null /*excludedPermissions=*/,
AppOpsManager.OP_NONE, null, false, false, getUserId());
} catch (RemoteException e) {
throw e.rethrowFromSystemServer();
}
}
- 还是以亮屏SCREEN_ON的广播继续讲解其发送流程
其调用方法是sendOrderedBroadcastAsUser(ContextImpl.java)->broadcastIntentWithFeature(ActivityManagerService.java)
//Notifier.java
private final Intent mScreenOnIntent;
//新建一个Intent，它的action是ACTION_SCREEN_ON，
//注意此处增加了
//FLAG_RECEIVER_REGISTERED_ONLY: 只允许动态注册的接收者接受
//FLAG_RECEIVER_FOREGROUND: 前台接收，也就是前台广播(10s超时)的队列
//FLAG_RECEIVER_VISIBLE_TO_INSTANT_APPS: 可以被即时app接收
mScreenOnIntent = new Intent(Intent.ACTION_SCREEN_ON);
mScreenOnIntent.addFlags(
Intent.FLAG_RECEIVER_REGISTERED_ONLY | Intent.FLAG_RECEIVER_FOREGROUND
| Intent.FLAG_RECEIVER_VISIBLE_TO_INSTANT_APPS);
//亮屏广播发送完成后才调用的
private final BroadcastReceiver mWakeUpBroadcastDone = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
//开始发送广播之前会打印类似“power_screen_broadcast_send: 1”的日志
//这里会在event log中打印类似“power_screen_broadcast_done: [1,125,1]“的日志
//里面包含了发送亮屏广播的时间，此处是“125 ms”
EventLog.writeEvent(EventLogTags.POWER_SCREEN_BROADCAST_DONE, 1,
SystemClock.uptimeMillis() - mBroadcastStartTime, 1);
sendNextBroadcast();
}
};
private void sendWakeUpBroadcast() {
if (DEBUG) {
Slog.d(TAG, "Sending wake up broadcast.");
}
if (mActivityManagerInternal.isSystemReady()) {
//调用的是ContextImpl的sendOrderedBroadcastAsUser去发送广播
//mScreenOnIntent是发送的亮屏广播
//mHandler是PowerManagerService.java的主线程，用来运行mWakeUpBroadcastDone
//mWakeUpBroadcastDone是亮屏广播发送完成后
mContext.sendOrderedBroadcastAsUser(mScreenOnIntent, UserHandle.ALL, null,
mWakeUpBroadcastDone, mHandler, 0, null, null);
} else {
EventLog.writeEvent(EventLogTags.POWER_SCREEN_BROADCAST_STOP, 2, 1);
sendNextBroadcast();
}
}
//ContextImpl.java
public void sendOrderedBroadcastAsUser(Intent intent, UserHandle user,
String receiverPermission, BroadcastReceiver resultReceiver, Handler scheduler,
int initialCode, String initialData, Bundle initialExtras) {
//多带了appOp=OP_NONE、options=null的参数
sendOrderedBroadcastAsUser(intent, user, receiverPermission, AppOpsManager.OP_NONE,
null, resultReceiver, scheduler, initialCode, initialData, initialExtras);
}
public void sendOrderedBroadcastAsUser(Intent intent, UserHandle user,
String receiverPermission, int appOp, Bundle options, BroadcastReceiver resultReceiver,
Handler scheduler, int initialCode, String initialData, Bundle initialExtras) {
IIntentReceiver rd = null;
if (resultReceiver != null) {
if (mPackageInfo != null) {
if (scheduler == null) {
//由于传入了scheduler(mHandler)，所以这里是不会进来的
scheduler = mMainThread.getHandler();
}
//进入的是这里获取IIntentReceiver rd(通过mPackageInfo、resultReceiver、scheduler构建)
rd = mPackageInfo.getReceiverDispatcher(
resultReceiver, getOuterContext(), scheduler,
mMainThread.getInstrumentation(), false);
} else {
if (scheduler == null) {
scheduler = mMainThread.getHandler();
}
rd = new LoadedApk.ReceiverDispatcher(resultReceiver, getOuterContext(),
scheduler, null, false).getIIntentReceiver();
}
}
String resolvedType = intent.resolveTypeIfNeeded(getContentResolver());
String[] receiverPermissions = receiverPermission == null ? null
: new String[] {
receiverPermission};
try {
intent.prepareToLeaveProcess(this);
//实际是调用的AMS的broadcastIntentWithFeature方法
ActivityManager.getService().broadcastIntentWithFeature(
mMainThread.getApplicationThread(), getAttributionTag(), intent, resolvedType,
rd, initialCode, initialData, initialExtras, receiverPermissions,
null /*excludedPermissions=*/, appOp, options, true, false,
user.getIdentifier());
} catch (RemoteException e) {
throw e.rethrowFromSystemServer();
}
}
3. 系统处理广播发送
3.1 AMS接收广播的请求
系统AMS通过broadcastIntentWithFeature接收广播的请求
//ActivityManagerService.java
//从context过来的都走的这个broadcastIntentWithFeature方法，带特性的发送广播
public final int broadcastIntentWithFeature(IApplicationThread caller, String callingFeatureId,
Intent intent, String resolvedType, IIntentReceiver resultTo,
int resultCode, String resultData, Bundle resultExtras,
String[] requiredPermissions, String[] excludedPermissions, int appOp, Bundle bOptions,
boolean serialized, boolean sticky, int userId) {
enforceNotIsolatedCaller("broadcastIntent");
synchronized(this) {
intent = verifyBroadcastLocked(intent);
//通过IApplicationThread获取调用者ProcessRecord callerApp
final ProcessRecord callerApp = getRecordForAppLOSP(caller);
final int callingPid = Binder.getCallingPid();
final int callingUid = Binder.getCallingUid();
final long origId = Binder.clearCallingIdentity();
try {
//获取callerApp、callingPid、callingUid用于广播发送参数传入
return broadcastIntentLocked(callerApp,
callerApp != null ? callerApp.info.packageName : null, callingFeatureId,
intent, resolvedType, resultTo, resultCode, resultData, resultExtras,
requiredPermissions, excludedPermissions, appOp, bOptions, serialized,
sticky, callingPid, callingUid, callingUid, callingPid, userId);
} finally {
Binder.restoreCallingIdentity(origId);
}
}
}
final int broadcastIntentLocked(ProcessRecord callerApp,
String callerPackage, String callerFeatureId, Intent intent, String resolvedType,
IIntentReceiver resultTo, int resultCode, String resultData,
Bundle resultExtras, String[] requiredPermissions, String[] excludedPermissions,
int appOp, Bundle bOptions, boolean ordered, boolean sticky, int callingPid,
int callingUid, int realCallingUid, int realCallingPid, int userId) {
//这里再次增加了3个参数allowBackgroundActivityStarts=false，tokenNeededForBackgroundActivityStarts=false
//broadcastAllowList=null
return broadcastIntentLocked(callerApp, callerPackage, callerFeatureId, intent,
resolvedType, resultTo, resultCode, resultData, resultExtras, requiredPermissions,
excludedPermissions, appOp, bOptions, ordered, sticky, callingPid, callingUid,
realCallingUid, realCallingPid, userId, false /* allowBackgroundActivityStarts */,
null /* tokenNeededForBackgroundActivityStarts */, null /* broadcastAllowList */);
}
3.2 修改增加默认flag解析可选广播参数BroadcastOptions
- 如默认会增加 FLAG_EXCLUDE_STOPPED_PACKAGES ，不让stop(如通过forcestop会设置)的三方app接收静态广播
- 根据是否粘性广播输出类似的日志：Broadcast (sticky) intent ordered=(true/false) userid=(userId)
- 解析BroadcastOptions brOptions广播可选参数
@GuardedBy("this")
final int broadcastIntentLocked(ProcessRecord callerApp, String callerPackage,
@Nullable String callerFeatureId, Intent intent, String resolvedType,
IIntentReceiver resultTo, int resultCode, String resultData,
Bundle resultExtras, String[] requiredPermissions,
String[] excludedPermissions, int appOp, Bundle bOptions,
boolean ordered, boolean sticky, int callingPid, int callingUid,
int realCallingUid, int realCallingPid, int userId,
boolean allowBackgroundActivityStarts,
@Nullable IBinder backgroundActivityStartsToken,
@Nullable int[] broadcastAllowList) {
intent = new Intent(intent);
//调用者是否即时app
final boolean callerInstantApp = isInstantApp(callerApp, callerPackage, callingUid);
// Instant Apps cannot use FLAG_RECEIVER_VISIBLE_TO_INSTANT_APPS
//如果调用者是即时app，不能添加FLAG_RECEIVER_VISIBLE_TO_INSTANT_APPS，可以让即时app接收的flag
if (callerInstantApp) {
intent.setFlags(intent.getFlags() & ~Intent.FLAG_RECEIVER_VISIBLE_TO_INSTANT_APPS);
}
// broadcastAllowList: 允许接收该广播uid的列表；一般包信息改变的时候才会传入，通过ContextImpl发送广播是不带这个参数的
// broadcastAllowList目前只在PMS的doSendBroadcast发送package相关广播的时候才可能使用到
// PackageManagerService.sendPackageBroadcast/sendMyPackageSuspendedOrUnsuspended->doSendBroadcast->
// ActivityManagerService.LocalService.broadcastIntent
if (userId == UserHandle.USER_ALL && broadcastAllowList != null) {
Slog.e(TAG, "broadcastAllowList only applies when sending to individual users. "
+ "Assuming restrictive whitelist.");
broadcastAllowList = new int[]{
};
}
// By default broadcasts do not go to stopped apps.
//默认广播是不发送给stop的应用的，类似于安装后进程从未启动过，或者给强行停止的应用，
//是无法通过接收静态注册的广播来启动的(具体在IntentResolver.java的buildResolveList会使用)
intent.addFlags(Intent.FLAG_EXCLUDE_STOPPED_PACKAGES);
// If we have not finished booting, don't allow this to launch new processes.
//mProcessesReady在systemReady的时候会设置为true
//在系统没有启动完成的时候，而且广播发送没有带FLAG_RECEIVER_BOOT_UPGRADE的flag
if (!mProcessesReady && (intent.getFlags()&Intent.FLAG_RECEIVER_BOOT_UPGRADE) == 0) {
//则默认只能发送到动态注册的接收者中，静态注册的全部无法接收
intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);
}
//DEBUG_BROADCAST_LIGHT这个是调试日志的开关，这里输出是否order有序广播
if (DEBUG_BROADCAST_LIGHT) Slog.v(TAG_BROADCAST,
(sticky ? "Broadcast sticky: ": "Broadcast: ") + intent
+ " ordered=" + ordered + " userid=" + userId);
//如果是非ordered的广播，而且有resultTo则输出warning的信息
//一般情况下orderd的广播才会设置resultTo(发送完成后返回完成的结果到发送者)
if ((resultTo != null) && !ordered) {
Slog.w(TAG, "Broadcast " + intent + " not ordered but result callback requested!");
}
//多用户判断，如果是callingUid、userId同一个用户组，则直接返回userId
userId = mUserController.handleIncomingUser(callingPid, callingUid, userId, true,
ALLOW_NON_FULL, "broadcast", callerPackage);
// Make sure that the user who is receiving this broadcast or its parent is running.
// If not, we will just skip it. Make an exception for shutdown broadcasts, upgrade steps.
//如果userId不是发送到所有用户USER_ALL(-1)，而且当前userId和它的父亲userId都没有在运行
if (userId != UserHandle.USER_ALL && !mUserController.isUserOrItsParentRunning(userId)) {
//如果调用者不是系统或者没有设置FLAG_RECEIVER_BOOT_UPGRADE，而且不是关机广播，
//则跳过本次广播发送，不允许stop的userId发送广播，原因是user已经stop了
if ((callingUid != SYSTEM_UID
|| (intent.getFlags() & Intent.FLAG_RECEIVER_BOOT_UPGRADE) == 0)
&& !Intent.ACTION_SHUTDOWN.equals(intent.getAction())) {
Slog.w(TAG, "Skipping broadcast of " + intent
+ ": user " + userId + " and its parent (if any) are stopped");
return ActivityManager.BROADCAST_FAILED_USER_STOPPED;
}
}
//获取其意图的action
final String action = intent.getAction();
BroadcastOptions brOptions = null;
//是否有传入BroadcastOptions的Bundle，开机广播有传入bOptions，亮屏幕广播没有bOptions
if (bOptions != null) {
//将Bundle转换成BroadcastOptions brOptions
brOptions = new BroadcastOptions(bOptions);
//如果mTemporaryAppAllowlistDuration的值大于0
if (brOptions.getTemporaryAppAllowlistDuration() > 0) {
// See if the caller is allowed to do this. Note we are checking against
// the actual real caller (not whoever provided the operation as say a
// PendingIntent), because that who is actually supplied the arguments.
// 检查一下realCallingPid/realCallingUid是否拥有CHANGE_DEVICE_IDLE_TEMP_WHITELIST(修改临时白名单)、
// START_ACTIVITIES_FROM_BACKGROUND(后台启动activity)、
// START_FOREGROUND_SERVICES_FROM_BACKGROUND(后台启动前台服务)的权限，
// 如果一个都没有，则不允许发送该广播，并抛出安全异常
// (在部分情况下callingPid/callingUid调用该发送广播的调用者，
// 于realCallingPid/realCallingUid真实调用者不是一样的)
if (checkComponentPermission(CHANGE_DEVICE_IDLE_TEMP_WHITELIST,
realCallingPid, realCallingUid, -1, true)
!= PackageManager.PERMISSION_GRANTED
&& checkComponentPermission(START_ACTIVITIES_FROM_BACKGROUND,
realCallingPid, realCallingUid, -1, true)
!= PackageManager.PERMISSION_GRANTED
&& checkComponentPermission(START_FOREGROUND_SERVICES_FROM_BACKGROUND,
realCallingPid, realCallingUid, -1, true)
!= PackageManager.PERMISSION_GRANTED) {
String msg = "Permission Denial: " + intent.getAction()
+ " broadcast from " + callerPackage + " (pid=" + callingPid
+ ", uid=" + callingUid + ")"
+ " requires "
+ CHANGE_DEVICE_IDLE_TEMP_WHITELIST + " or "
+ START_ACTIVITIES_FROM_BACKGROUND + " or "
+ START_FOREGROUND_SERVICES_FROM_BACKGROUND;
Slog.w(TAG, msg);
throw new SecurityException(msg);
}
}
//如果带有mDontSendToRestrictedApps不发送给受限制的app
// callingUid不在mActiveUids中，而且callingUid/callerPackage后台限制操作
// 则由于“background restrictions”不允许发送广播
if (brOptions.isDontSendToRestrictedApps()
&& !isUidActiveLOSP(callingUid)
&& isBackgroundRestrictedNoCheck(callingUid, callerPackage)) {
Slog.i(TAG, "Not sending broadcast " + action + " - app " + callerPackage
+ " has background restrictions");
return ActivityManager.START_CANCELED;
}
//是否允许mAllowBackgroundActivityStarts后台启动activity
if (brOptions.allowsBackgroundActivityStarts()) {
// See if the caller is allowed to do this. Note we are checking against
// the actual real caller (not whoever provided the operation as say a
// PendingIntent), because that who is actually supplied the arguments.
//如果没有START_ACTIVITIES_FROM_BACKGROUND则抛出权限异常
if (checkComponentPermission(
android.Manifest.permission.START_ACTIVITIES_FROM_BACKGROUND,
realCallingPid, realCallingUid, -1, true)
!= PackageManager.PERMISSION_GRANTED) {
String msg = "Permission Denial: " + intent.getAction()
+ " broadcast from " + callerPackage + " (pid=" + callingPid
+ ", uid=" + callingUid + ")"
+ " requires "
+ android.Manifest.permission.START_ACTIVITIES_FROM_BACKGROUND;
Slog.w(TAG, msg);
throw new SecurityException(msg);
} else {
//否者将allowBackgroundActivityStarts设置成true，允许后台启动activity
allowBackgroundActivityStarts = true;
// We set the token to null since if it wasn't for it we'd allow anyway here
backgroundActivityStartsToken = null;
}
}
}
3.4 保护广播isProtectedBroadcast、特定action的处理
- 识别是否保护广播，这类广播不能给系统之外的app调用；而系统尽量发送保护广播，不然也会发出警告
- 后台是否可以接收广播的识别(如果在system/etc、/product/etc等地方加入“allow-implicit-broadcast”的广播则可以让后台接收，
会加上FLAG_RECEIVER_INCLUDE_BACKGROUND的flag) - 特定action如包状态改变等的广播的处理
// Verify that protected broadcasts are only being sent by system code,
// and that system code is only sending protected broadcasts.
//保护广播的判断逻辑isProtectedBroadcast，这类广播只有系统才能发送
final boolean isProtectedBroadcast;
try {
//查询该广播是否包含在mProtectedBroadcasts，在isProtectedBroadcast也可以增加字符串过滤条件
//例如在frameworks/base/core/res/AndroidManifest.xml等定义的带有“protected-broadcast”的广播
// <protected-broadcast android:name="android.intent.action.SCREEN_ON" />
isProtectedBroadcast = AppGlobals.getPackageManager().isProtectedBroadcast(action);
} catch (RemoteException e) {
Slog.w(TAG, "Remote exception", e);
return ActivityManager.BROADCAST_SUCCESS;
}
final boolean isCallerSystem;
//判断是否系统调用
switch (UserHandle.getAppId(callingUid)) {
case ROOT_UID:
case SYSTEM_UID:
case PHONE_UID:
case BLUETOOTH_UID:
case NFC_UID:
case SE_UID:
case NETWORK_STACK_UID:
//root用户、系统、phone、蓝牙、nfc、安全、网络等相关调用则被认为是系统
isCallerSystem = true;
break;
default:
//其它就看是否常驻内存，如果是常驻内存调用，也被认为是系统
isCallerSystem = (callerApp != null) && callerApp.isPersistent();
break;
}
// First line security check before anything else: stop non-system apps from
// sending protected broadcasts.
//如果不是系统调用，会进行安全检查
if (!isCallerSystem) {
//如果是保护的广播，则不是系统进程，不允许发送，抛出权限异常
if (isProtectedBroadcast) {
String msg = "Permission Denial: not allowed to send broadcast "
+ action + " from pid="
+ callingPid + ", uid=" + callingUid;
Slog.w(TAG, msg);
throw new SecurityException(msg);
} else if (AppWidgetManager.ACTION_APPWIDGET_CONFIGURE.equals(action)
|| AppWidgetManager.ACTION_APPWIDGET_UPDATE.equals(action)) {
// Special case for compatibility: we don't want apps to send this,
// but historically it has not been protected and apps may be using it
// to poke their own app widget. So, instead of making it protected,
// just limit it to the caller.
//如果是widget配置(ACTION_APPWIDGET_CONFIGURE)和更新(ACTION_APPWIDGET_UPDATE)
//则调用callerPackage不能是空
if (callerPackage == null) {
String msg = "Permission Denial: not allowed to send broadcast "
+ action + " from unknown caller.";
Slog.w(TAG, msg);
throw new SecurityException(msg);
//如果调用组件不等于null
} else if (intent.getComponent() != null) {
// They are good enough to send to an explicit component... verify
// it is being sent to the calling app.
//这种情况只能自己发送给自己，不然抛出权限异常
if (!intent.getComponent().getPackageName().equals(
callerPackage)) {
String msg = "Permission Denial: not allowed to send broadcast "
+ action + " to "
+ intent.getComponent().getPackageName() + " from "
+ callerPackage;
Slog.w(TAG, msg);
throw new SecurityException(msg);
}
} else {
// Limit broadcast to their own package.
//这类广播只能发给它自己，用于自身widget的更新
intent.setPackage(callerPackage);
}
}
}
//这个是广播超时豁免只有ACTION_PRE_BOOT_COMPLETED才会设置
//设置了之后这个广播不会超时，谨慎使用
boolean timeoutExempt = false;
if (action != null) {
//查看是否background的进程也可以接收该广播，具体列表在SystemConfig.java的mAllowImplicitBroadcasts
//这个列表是扫描**/etc(如system/etc/sysconfig/framework-sysconfig.xml、
// /product/etc/sysconfig/google.xml)带有“<allow-implicit-broadcast”的广播
// 如：google的云推送”com.google.android.c2dm.intent.RECEIVE“、simcard状态改变
// android.intent.action.SIM_STATE_CHANGED就是这类广播
if (getBackgroundLaunchBroadcasts().contains(action)) {
if (DEBUG_BACKGROUND_CHECK) {
Slog.i(TAG, "Broadcast action " + action + " forcing include-background");
}
//直接增加可以被后台进程接收的flag FLAG_RECEIVER_INCLUDE_BACKGROUND
// (如何使用在讲解BroadcastQueue的processNextBroadcastLocked时会说明)
intent.addFlags(Intent.FLAG_RECEIVER_INCLUDE_BACKGROUND);
}
switch (action) {
case Intent.ACTION_UID_REMOVED:
case Intent.ACTION_PACKAGE_REMOVED:
case Intent.ACTION_PACKAGE_CHANGED:
case Intent.ACTION_EXTERNAL_APPLICATIONS_UNAVAILABLE:
case Intent.ACTION_EXTERNAL_APPLICATIONS_AVAILABLE:
case Intent.ACTION_PACKAGES_SUSPENDED:
case Intent.ACTION_PACKAGES_UNSUSPENDED:
// Handle special intents: if this broadcast is from the package
// manager about a package being removed, we need to remove all of
// its activities from the history stack.
// 如果是ACTION_UID_REMOVED/ACTION_PACKAGE_REMOVED/ACTION_PACKAGE_CHANGED/
// ACTION_EXTERNAL_APPLICATIONS_UNAVAILABLE/ACTION_EXTERNAL_APPLICATIONS_AVAILABLE/
// ACTION_PACKAGES_SUSPENDED/ACTION_PACKAGES_UNSUSPENDED这类广播，
// 则发送广播需要BROADCAST_PACKAGE_REMOVED的权限，不然是没法发送的
if (checkComponentPermission(
android.Manifest.permission.BROADCAST_PACKAGE_REMOVED,
callingPid, callingUid, -1, true)
!= PackageManager.PERMISSION_GRANTED) {
String msg = "Permission Denial: " + intent.getAction()
+ " broadcast from " + callerPackage + " (pid=" + callingPid
+ ", uid=" + callingUid + ")"
+ " requires "
+ android.Manifest.permission.BROADCAST_PACKAGE_REMOVED;
Slog.w(TAG, msg);
throw new SecurityException(msg);
}
switch (action) {
case Intent.ACTION_UID_REMOVED:
final int uid = getUidFromIntent(intent);
//如果发送的是ACTION_UID_REMOVED的广播
if (uid >= 0) {
//电池状态服务的removeUid
mBatteryStatsService.removeUid(uid);
//mAppOpsService app操作相关管理的处理
if (intent.getBooleanExtra(Intent.EXTRA_REPLACING, false)) {
mAppOpsService.resetAllModes(UserHandle.getUserId(uid),
intent.getStringExtra(Intent.EXTRA_PACKAGE_NAME));
} else {
mAppOpsService.uidRemoved(uid);
}
}
break;
case Intent.ACTION_EXTERNAL_APPLICATIONS_UNAVAILABLE:
// If resources are unavailable just force stop all those packages
// and flush the attribute cache as well.
String list[] =
intent.getStringArrayExtra(Intent.EXTRA_CHANGED_PACKAGE_LIST);
if (list != null && list.length > 0) {
for (int i = 0; i < list.length; i++) {
forceStopPackageLocked(list[i], -1, false, true, true,
false, false, userId, "storage unmount");
}
mAtmInternal.cleanupRecentTasksForUser(UserHandle.USER_ALL);
sendPackageBroadcastLocked(
ApplicationThreadConstants.EXTERNAL_STORAGE_UNAVAILABLE,
list, userId);
}
break;
case Intent.ACTION_EXTERNAL_APPLICATIONS_AVAILABLE:
mAtmInternal.cleanupRecentTasksForUser(UserHandle.USER_ALL);
break;
case Intent.ACTION_PACKAGE_REMOVED:
case Intent.ACTION_PACKAGE_CHANGED:
//应用移除或者改变
Uri data = intent.getData();
String ssp;
if (data != null && (ssp=data.getSchemeSpecificPart()) != null) {
boolean removed = Intent.ACTION_PACKAGE_REMOVED.equals(action);
final boolean replacing =
intent.getBooleanExtra(Intent.EXTRA_REPLACING, false);
final boolean killProcess =
!intent.getBooleanExtra(Intent.EXTRA_DONT_KILL_APP, false);
final boolean fullUninstall = removed && !replacing;
if (removed) {
if (killProcess) {
forceStopPackageLocked(ssp, UserHandle.getAppId(
intent.getIntExtra(Intent.EXTRA_UID, -1)),
false, true, true, false, fullUninstall, userId,
removed ? "pkg removed" : "pkg changed");
} else {
// Kill any app zygotes always, since they can't fork new
// processes with references to the old code
forceStopAppZygoteLocked(ssp, UserHandle.getAppId(
intent.getIntExtra(Intent.EXTRA_UID, -1)),
userId);
}
final int cmd = killProcess
? ApplicationThreadConstants.PACKAGE_REMOVED
: ApplicationThreadConstants.PACKAGE_REMOVED_DONT_KILL;
sendPackageBroadcastLocked(cmd,
new String[] {
ssp}, userId);
if (fullUninstall) {
mAppOpsService.packageRemoved(
intent.getIntExtra(Intent.EXTRA_UID, -1), ssp);
// Remove all permissions granted from/to this package
mUgmInternal.removeUriPermissionsForPackage(ssp, userId,
true, false);
mAtmInternal.removeRecentTasksByPackageName(ssp, userId);
mServices.forceStopPackageLocked(ssp, userId);
mAtmInternal.onPackageUninstalled(ssp);
mBatteryStatsService.notePackageUninstalled(ssp);
}
} else {
if (killProcess) {
final int extraUid = intent.getIntExtra(Intent.EXTRA_UID,
-1);
synchronized (mProcLock) {
mProcessList.killPackageProcessesLSP(ssp,
UserHandle.getAppId(extraUid),
userId, ProcessList.INVALID_ADJ,
ApplicationExitInfo.REASON_USER_REQUESTED,
ApplicationExitInfo.SUBREASON_UNKNOWN,
"change " + ssp);
}
}
cleanupDisabledPackageComponentsLocked(ssp, userId,
intent.getStringArrayExtra(
Intent.EXTRA_CHANGED_COMPONENT_NAME_LIST));
mServices.schedulePendingServiceStartLocked(ssp, userId);
} }
break;
case Intent.ACTION_PACKAGES_SUSPENDED:
case Intent.ACTION_PACKAGES_UNSUSPENDED:
final boolean suspended = Intent.ACTION_PACKAGES_SUSPENDED.equals(
intent.getAction());
final String[] packageNames = intent.getStringArrayExtra(
Intent.EXTRA_CHANGED_PACKAGE_LIST);
final int userIdExtra = intent.getIntExtra(
Intent.EXTRA_USER_HANDLE, UserHandle.USER_NULL);
mAtmInternal.onPackagesSuspendedChanged(packageNames, suspended,
userIdExtra);
break;
}
break;
case Intent.ACTION_PACKAGE_REPLACED:
{
final Uri data = intent.getData();
final String ssp;
if (data != null && (ssp = data.getSchemeSpecificPart()) != null) {
ApplicationInfo aInfo = null;
try {
aInfo = AppGlobals.getPackageManager()
.getApplicationInfo(ssp, STOCK_PM_FLAGS, userId);
} catch (RemoteException ignore) {
}
if (aInfo == null) {
Slog.w(TAG, "Dropping ACTION_PACKAGE_REPLACED for non-existent pkg:"
+ " ssp=" + ssp + " data=" + data);
return ActivityManager.BROADCAST_SUCCESS;
}
updateAssociationForApp(aInfo);
mAtmInternal.onPackageReplaced(aInfo);
mServices.updateServiceApplicationInfoLocked(aInfo);
sendPackageBroadcastLocked(ApplicationThreadConstants.PACKAGE_REPLACED,
new String[] {
ssp}, userId);
}
break;
}
case Intent.ACTION_PACKAGE_ADDED:
{
//应用安装
// Special case for adding a package: by default turn on compatibility mode.
Uri data = intent.getData();
String ssp;
if (data != null && (ssp = data.getSchemeSpecificPart()) != null) {
final boolean replacing =
intent.getBooleanExtra(Intent.EXTRA_REPLACING, false);
mAtmInternal.onPackageAdded(ssp, replacing);
try {
ApplicationInfo ai = AppGlobals.getPackageManager().
getApplicationInfo(ssp, STOCK_PM_FLAGS, 0);
mBatteryStatsService.notePackageInstalled(ssp,
ai != null ? ai.longVersionCode : 0);
} catch (RemoteException e) {
}
}
break;
}
case Intent.ACTION_PACKAGE_DATA_CLEARED:
{
//应用数据清除
Uri data = intent.getData();
String ssp;
if (data != null && (ssp = data.getSchemeSpecificPart()) != null) {
mAtmInternal.onPackageDataCleared(ssp);
}
break;
}
case Intent.ACTION_TIMEZONE_CHANGED:
// If this is the time zone changed action, queue up a message that will reset
// the timezone of all currently running processes. This message will get
// queued up before the broadcast happens.
//时区改变
mHandler.sendEmptyMessage(UPDATE_TIME_ZONE);
break;
case Intent.ACTION_TIME_CHANGED:
// EXTRA_TIME_PREF_24_HOUR_FORMAT is optional so we must distinguish between
// the tri-state value it may contain and "unknown".
// For convenience we re-use the Intent extra values.
//系统时间改变
final int NO_EXTRA_VALUE_FOUND = -1;
final int timeFormatPreferenceMsgValue = intent.getIntExtra(
Intent.EXTRA_TIME_PREF_24_HOUR_FORMAT,
NO_EXTRA_VALUE_FOUND /* defaultValue */);
// Only send a message if the time preference is available.
if (timeFormatPreferenceMsgValue != NO_EXTRA_VALUE_FOUND) {
Message updateTimePreferenceMsg =
mHandler.obtainMessage(UPDATE_TIME_PREFERENCE_MSG,
timeFormatPreferenceMsgValue, 0);
mHandler.sendMessage(updateTimePreferenceMsg);
}
mBatteryStatsService.noteCurrentTimeChanged();
break;
case ConnectivityManager.ACTION_CLEAR_DNS_CACHE:
mHandler.sendEmptyMessage(CLEAR_DNS_CACHE_MSG);
break;
case Proxy.PROXY_CHANGE_ACTION:
mHandler.sendMessage(mHandler.obtainMessage(UPDATE_HTTP_PROXY_MSG));
break;
case android.hardware.Camera.ACTION_NEW_PICTURE:
case android.hardware.Camera.ACTION_NEW_VIDEO:
// In N we just turned these off; in O we are turing them back on partly,
// only for registered receivers. This will still address the main problem
// (a spam of apps waking up when a picture is taken putting significant
// memory pressure on the system at a bad point), while still allowing apps
// that are already actively running to know about this happening.
intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);
break;
case android.security.KeyChain.ACTION_TRUST_STORE_CHANGED:
mHandler.sendEmptyMessage(HANDLE_TRUST_STORAGE_UPDATE_MSG);
break;
case "com.android.launcher.action.INSTALL_SHORTCUT":
// As of O, we no longer support this broadcasts, even for pre-O apps.
// Apps should now be using ShortcutManager.pinRequestShortcut().
Log.w(TAG, "Broadcast " + action
+ " no longer supported. It will not be delivered.");
return ActivityManager.BROADCAST_SUCCESS;
case Intent.ACTION_PRE_BOOT_COMPLETED:
//如果是ACTION_PRE_BOOT_COMPLETED广播则设置超时豁免timeoutExempt = true
timeoutExempt = true;
break;
case Intent.ACTION_CLOSE_SYSTEM_DIALOGS:
//需要有BROADCAST_CLOSE_SYSTEM_DIALOGS的权限，不然直接返回
if (!mAtmInternal.checkCanCloseSystemDialogs(callingPid, callingUid,
callerPackage)) {
// Returning success seems to be the pattern here
return ActivityManager.BROADCAST_SUCCESS;
}
break;
}
if (Intent.ACTION_PACKAGE_ADDED.equals(action) ||
Intent.ACTION_PACKAGE_REMOVED.equals(action) ||
Intent.ACTION_PACKAGE_REPLACED.equals(action)) {
final int uid = getUidFromIntent(intent);
if (uid != -1) {
final UidRecord uidRec = mProcessList.getUidRecordLOSP(uid);
if (uidRec != null) {
uidRec.updateHasInternetPermission();
}
}
}
}
3.5 发送粘性广播的处理
将粘性广播添加到AMS的mStickyBroadcasts(key是用户组，value是粘性广播列表stickies)中，
单个用户组的粘性广播列表stickies(key是action，value是intent)
已经发送的粘性广播会放入AMS的mStickyBroadcasts中，后面动态注册的接收者就可以在注册的时候就接收这类粘性广播， 因为系统有保存这类广播
// Add to the sticky list if requested.
// 是否粘性广播，可以通过ContextImpl.java的sendStickyBroadcast/sendStickyBroadcastAsUser/
// sendStickyOrderedBroadcast/sendStickyOrderedBroadcastAsUser来进行发送
if (sticky) {
//粘性广播需要拥有"android.permission.BROADCAST_STICKY"的权限
if (checkPermission(android.Manifest.permission.BROADCAST_STICKY,
callingPid, callingUid)
!= PackageManager.PERMISSION_GRANTED) {
String msg = "Permission Denial: broadcastIntent() requesting a sticky broadcast from pid="
+ callingPid + ", uid=" + callingUid
+ " requires " + android.Manifest.permission.BROADCAST_STICKY;
Slog.w(TAG, msg);
throw new SecurityException(msg);
}
//这类广播不能带有requiredPermissions，否则直接返回
if (requiredPermissions != null && requiredPermissions.length > 0) {
Slog.w(TAG, "Can't broadcast sticky intent " + intent
+ " and enforce permissions " + Arrays.toString(requiredPermissions));
return ActivityManager.BROADCAST_STICKY_CANT_HAVE_PERMISSION;
}
//粘性广播不能指定发送到相关组件，否则发出安全异常
if (intent.getComponent() != null) {
throw new SecurityException(
"Sticky broadcasts can't target a specific component");
}
// We use userId directly here, since the "all" target is maintained
// as a separate set of sticky broadcasts.
//如果userId不是发送给所有用户USER_ALL(-1)
if (userId != UserHandle.USER_ALL) {
// But first, if this is not a broadcast to all users, then
// make sure it doesn't conflict with an existing broadcast to
// all users.
//则取出保存粘性广播的列表mStickyBroadcasts里面相同action的Intent
ArrayMap<String, ArrayList<Intent>> stickies =
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