BroadcastReceiver 源码分析，一线互联网大厂中高级 Android 面试真题收录
ContextImpl.java
public void sendBroadcast(Intent intent) {
warnIfCallingFromSystemProcess();
String resolvedType = intent.resolveTypeIfNeeded(getContentResolver());
intent.prepareToLeaveProcess(this);
ActivityManager.getService().broadcastIntent(
mMainThread.getApplicationThread(), intent, resolvedType, null,
Activity.RESULT_OK, null, null, null, AppOpsManager.OP_NONE, null, false, false,
getUserId());
}
ActivityManagerService.java
public final int broadcastIntent(IApplicationThread caller,
Intent intent, String resolvedType, IIntentReceiver resultTo,
int resultCode, String resultData, Bundle resultExtras,
String[] requiredPermissions, int appOp, Bundle bOptions,
boolean serialized, boolean sticky, int userId) {
···
int res = broadcastIntentLocked(callerApp,
callerApp != null ? callerApp.info.packageName : null,
intent, resolvedType, resultTo, resultCode, resultData, resultExtras,
requiredPermissions, appOp, bOptions, serialized, sticky,
callingPid, callingUid, userId);
···
}
}
final int broadcastIntentLocked(ProcessRecord callerApp,
String callerPackage, 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 userId){
···
//1 找到匹配的 Receiver 列表
registeredReceivers = mReceiverResolver.queryIntent(intent,
resolvedType, false /defaultOnly/, userId);
int NR = registeredReceivers != null ? registeredReceivers.size() : 0;
//是否是有序广播，并且存在接收者
if (!ordered && NR > 0) {
//取出普通任务 queue
final BroadcastQueue queue = broadcastQueueForIntent(intent);
BroadcastRecord r = new BroadcastRecord(queue, intent, callerApp,
callerPackage, callingPid, callingUid, callerInstantApp, resolvedType,
requiredPermissions, appOp, brOptions, registeredReceivers, resultTo,
resultCode, resultData, resultExtras, ordered, sticky, false, userId);
//添加到并行分发 queue
queue.enqueueParallelBroadcastLocked(r);
//开始分发广播
queue.scheduleBroadcastsLocked();
registeredReceivers = null;
NR = 0;
}
}
queue.scheduleBroadcastsLocked();会发送 BROADCAST_INTENT_MSG，调用 processNextBroadcast(true);
BroadcastQueue.java
final void processNextBroadcast(boolean fromMsg) {
synchronized (mService) {
processNextBroadcastLocked(fromMsg, false);
}
}
final void processNextBroadcastLocked(boolean fromMsg, boolean skipOomAdj){
while (mParallelBroadcasts.size() > 0) {
r = mParallelBroadcasts.remove(0);
final int N = r.receivers.size();
//依次取出分发
for (int i=0; i<N; i++) {
Object target = r.receivers.get(i);
//调用
deliverToRegisteredReceiverLocked(r, (BroadcastFilter)target, false, i);
}
}
}
private void deliverToRegisteredReceiverLocked(BroadcastRecord r,
BroadcastFilter filter, boolean ordered, int index) {
··· //分发广播到客户端
performReceiveLocked(filter.receiverList.app, filter.receiverList.receiver,
new Intent(r.intent), r.resultCode, r.resultData,
r.resultExtras, r.ordered, r.initialSticky, r.userId);
····
}
void performReceiveLocked(ProcessRecord app, IIntentReceiver receiver,
Intent intent, int resultCode, String data, Bundle extras,
boolean ordered, boolean sticky, int sendingUser) throws RemoteException {
// Send the intent to the receiver asynchronously using one-way binder calls.
//判断应是否为空
if (app != null) {
if (app.thread != null) {
//通知客户端
分发广播，Binder 采用 oneway 异步 应用端会自动串行化
app.thread.scheduleRegisteredReceiver(receiver, intent, resultCode,
data, extras, ordered, sticky, sendingUser, app.repProcState);
}
} else {
receiver.performReceive(intent, resultCode, data, extras, ordered,
sticky, sendingUser);
}
}
AMS 端的 app.thread.scheduleRegisteredReceiver()，会调用到注册时注册的 InnerReceiver 的 performReceive 方法
ActivityThread.java
public void scheduleRegisteredReceiver(IIntentReceiver receiver, Intent intent,
int resultCode, String dataStr, Bundle extras, boolean ordered,
boolean sticky, int sendingUser, int processState) throws RemoteException {
updateProcessState(processState, false);
//1
receiver.performReceive(intent, resultCode, dataStr, extras, ordered,
sticky, sendingUser);
}
InnerReceiver.java
public void performReceive(Intent intent, int resultCode, String data,
Bundle extras, boolean ordered, boolean sticky, int sendingUser) {
final LoadedApk.ReceiverDispatcher rd;
···
if (rd != null) {
//调用 LoadedApk.ReceiverDispatcher 的 performReceive
rd.performReceive(intent, resultCode, data, extras,
ordered, sticky, sendingUser);
···
}
}
···
LoadedApk.ReceiverDispatcher.java
public void performReceive(Intent intent, int resultCode, String data,
Bundle extras, boolean ordered, boolean sticky, int sendingUser) {
final Args args = new Args(intent, resultCode, data, extras, ordered,
sticky, sendingUser);
···
//向 ActivityThread 发送一个 Runnable
if (intent == null || !mActivityThread.post(args.getRunnable())) {
}
}
Args.java
public final Runnable getRunnable() {
return () -> {
final BroadcastReceiver receiver = mReceiver;
final boolean ordered = mOrdered;
=
final IActivityManager mgr = ActivityManager.getService();
···
receiver.setPendingResult(this);
//这里触发了 BoradcastReciever 回调
receiver.onReceive(mContext, intent);
···
};
}
=========================================================================
1、首先动态注册 BroadcastReceiver 到 AMS，将他们存储在一个 Map 中，Map 的 key 是 IIntentReceiver 用于回调注册端，value 是一个 ReceiverList
2、发送这发送 Intent 到 AMS，筛选出匹配的 ReceiverList，遍历通知注册端
=======================================================================================
PackageParser.java
private boolean parseBaseApplication(Package owner, Resources res,
XmlResourceParser parser, int flags, String[] outError){
else if (tagName.equals("receiver")) {
Activity a = parseActivity(owner, res, parser, flags, outError, cachedArgs,
true, false);
owner.receivers.add(a);
}
}
1、将 receiver 解析成一个 Activity（这个 Activity 表示的是一个组件）对象，添加到 receivers 的列表中，receivers 是一个 ArrayList
============================================================================
5.1 调用 Context 的 sendBroadcast
最后会调用到
ContextImpl.java
public void sendBroadcast(Intent intent) {
warnIfCallingFromSystemProcess();
String resolvedType = intent.resolveTypeIfNeeded(getContentResolver());
intent.prepareToLeaveProcess(this);
ActivityManager.getService().broadcastIntent(
mMainThread.getApplicationThread(), intent, resolvedType, null,
Activity.RESULT_OK, null, null, null, AppOpsManager.OP_NONE, null, false, false,
getUserId());
}
ActivityManagerService.java
public final int broadcastIntent(IApplicationThread caller,
Intent intent, String resolvedType, IIntentReceiver resultTo,
int resultCode, String resultData, Bundle resultExtras,
String[] requiredPermissions, int appOp, Bundle bOptions,
boolean serialized, boolean sticky, int userId) {
···
int res = broadcastIntentLocked(callerApp,
callerApp != null ? callerApp.info.packageName : null,
intent, resolvedType, resultTo, resultCode, resultData, resultExtras,
requiredPermissions, appOp, bOptions, serialized, sticky,
callingPid, callingUid, userId);
···
}
}
final int broadcastIntentLocked(ProcessRecord callerApp,
String callerPackage, 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 userId){
···
//获取接收静态广播
receivers = collectReceiverComponents(intent, resolvedType, callingUid, users);
//通过 Intent 查找能接受的动态广播
registeredReceivers = mReceiverResolver.queryIntent(intent,
resolvedType, false /defaultOnly/, userId);
int NR = registeredReceivers != null ? registeredReceivers.size() : 0;
if (!ordered && NR > 0) {
//处理动态广播，添加到并行分发队列，OneWay 发送 binder 处理是串行的
}
//给没有处理完的动态 receiver（order 是 true），跟静态 receiver 合并到一起
if ((receivers != null && receivers.size() > 0){
//处理剩下的 receiver。加到串行分发队列
//获取 queue
BroadcastQueue queue = broadcastQueueForIntent(intent);
BroadcastRecord r = new BroadcastRecord(queue, intent, callerApp,
callerPackage, callingPid, callingUid, callerInstantApp, resolvedType,
requiredPermissions, appOp, brOptions, receivers, resultTo, resultCode,
resultData, resultExtras, ordered, sticky, false, userId);
//添加到串行分发 queue
queue.enqueueOrderedBroadcastLocked(r);
//处理分发
queue.scheduleBroadcastsLocked();
}
return ActivityManager.BROADCAST_SUCCESS;
}
queue.scheduleBroadcastsLocked();会发送 BROADCAST_INTENT_MSG，调用 processNextBroadcast(true);
BroadcastQueue.java
final void processNextBroadcast(boolean fromMsg) {
synchronized (mService) {
processNextBroadcastLocked(fromMsg, false);
}
}
final void processNextBroadcastLocked(boolean fromMsg, boolean skipOomAdj){
while (mParallelBroadcasts.size() > 0) {
r = mParallelBroadcasts.remove(0);
final int N = r.receivers.size()
for (int i=0; i<N; i++) {
Object target = r.receivers.get(i);
//先并行分发，然后接下来分发串行广播
deliverToRegisteredReceiverLocked(r, (BroadcastFilter)target, false, i);
}
}
//如果有 pedding 广播，先直接返回，这个广播在等待应用进程启动
//如果当前广播分发超时了，废弃这个广播，处理下一个广播
broadcastTimeoutLocked(false);
//如果没有超时，并且在分发中，就先返回。什么也不做
//如果当前的广播已经分发完一个 receiver，就继续分发下一个 receiver
//如果这个 receiver 是动态注册的 receiver 就直接分发
//如果这个 receiver 是静态注册的 receiver，先看进程启动没有
//如果进程启动了，就直接分发
processCurBroadcastLocked(r, app, skipOomAdj);
//没启动的话就先启动进程，然后给广播标记为 pedding
//进程启动后 attachApplication 时继续处理这个 pending 的广播
}
BroadcastQueue.java
//处理超时
final void broadcastTimeoutLocked(boolean fromMsg) {
BroadcastRecord r = mOrderedBroadcasts.get(0);
Object curReceiver = r.receivers.get(r.nextReceiver-1);
//找到当前分发 receiver 对应的进程
if (mPendingBroadcast == r) {
mPendingBroadcast = null;
}
// Move on to the next receiver.
finishReceiverLocked(r, r.resultCode, r.resultData,
r.resultExtras, r.resultAbort, false);
//发送消息处理下一个 receiver
scheduleBroadcastsLocked();
if (!debugging && anrMessage != null) {
// Post the ANR to the handler since we do not want to process ANRs while
// potentially holding our lock.
//超时显示 ANR
mHandler.post(new AppNotResponding(app, anrMessage));
}
}
BroadcastQueue.java
//接收进程存在，通知接收进程
private final void processCurBroadcastLocked(BroadcastRecord r,
ProcessRecord app, boolean skipOomAdj) throws RemoteException {
···
app.thread.scheduleReceiver(new Intent(r.intent), r.curReceiver,
mService.compatibilityInfoForPackageLocked(r.curReceiver.applicationInfo),
r.resultCode, r.resultData, r.resultExtras, r.ordered, r.userId,
app.repProcState);
···
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