前言
在【Service启动流程之startService】 中，我们已经分析了startService的流程，这篇就继续讲bindService的流程，他们两有很多相似之处。同样，流程图在总结处。
我们在调用bindService方法时候，实际调用的是ContextImpl的实现。
1. ContextImpl
代码路径：frameworks\base\core\java\android\app\ContextImpl.java
1.1 bindService
@Override
public boolean bindService(Intent service, ServiceConnection conn, int flags) {
warnIfCallingFromSystemProcess();
return bindServiceCommon(service, conn, flags, null, mMainThread.getHandler(), null,
getUser());
}
1.2 bindServiceCommon
private boolean bindServiceCommon(Intent service, ServiceConnection conn,
int flags, String instanceName, Handler handler,
Executor executor, UserHandle user) {
IServiceConnection sd;
if (mPackageInfo != null) {
// 将ServiceConnection 通过LoadedApk包装到 ServiceDispatcher 中
if (executor != null) {
sd = mPackageInfo.getServiceDispatcher(conn, getOuterContext(), executor, flags);
} else {
sd = mPackageInfo.getServiceDispatcher(conn, getOuterContext(), handler, flags);
}
}
try {
IBinder token = getActivityToken();
if (token == null && (flags&BIND_AUTO_CREATE) == 0 && mPackageInfo != null
&& mPackageInfo.getApplicationInfo().targetSdkVersion
< android.os.Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
flags |= BIND_WAIVE_PRIORITY;
}
service.prepareToLeaveProcess(this);
// 调用 AMS 接口
int res = ActivityManager.getService().bindServiceInstance(
mMainThread.getApplicationThread(), getActivityToken(), service,
service.resolveTypeIfNeeded(getContentResolver()),
sd, flags, instanceName, getOpPackageName(), user.getIdentifier());
return res != 0;
} catch (RemoteException e) {
throw e.rethrowFromSystemServer();
}
}
2. LoaderApk
代码路径：frameworks\base\core\java\android\app\LoadedApk.java
getServiceDispatcher 直接调用getServiceDispatcherCommon 方法
2.1 getServiceDispatcherCommon
private IServiceConnection getServiceDispatcherCommon(ServiceConnection c,
Context context, Handler handler, Executor executor, int flags) {
synchronized (mServices) {
LoadedApk.ServiceDispatcher sd = null;
ArrayMap<ServiceConnection, LoadedApk.ServiceDispatcher> map = mServices.get(context);
if (map != null) {
sd = map.get(c);
}
if (sd == null) {
if (executor != null) {
// 将ServiceConnection 保存到ServiceDispatcher中
sd = new ServiceDispatcher(c, context, executor, flags);
} else {
sd = new ServiceDispatcher(c, context, handler, flags);
}
if (map == null) {
map = new ArrayMap<>();
mServices.put(context, map);
}
map.put(c, sd);
} else {
sd.validate(context, handler, executor);
}
// 最后返回的是一个bind对象，即IServiceConnection
return sd.getIServiceConnection();
}
}
3. ActivityManagerService
代码路径：frameworks\base\services\core\java\com\android\server\am\ActivityManagerService.java
3.1 bindServiceInstance
private int bindServiceInstance(IApplicationThread caller, IBinder token,
Intent service, String resolvedType,
ServiceConnection connection ...) {
....
try {
synchronized (this) {
// 调用ActiveServices的bindServiceLocked
return mServices.bindServiceLocked(caller, token, service, resolvedType, connection,flags, instanceName, isSdkSandboxService, sdkSandboxClientAppUid, sdkSandboxClientAppPackage, callingPackage, userId);
}
} finally {
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
}
}
4. ActiveService
代码路径：frameworks\base\services\core\java\com\android\server\am\ActiveServices.java
4.1 bindServiceLocked
其中：
- ServiceRecord：用于描述一个Service
- processRecord：一个进程的信息
- ConnectionRecord：用于描述应用程序进程和Service建立的通信
- AppBindRecord：维护Service与应用进程的关联，包含通信记录ArraySet，绑定Service的intent。
- IntentBindRecord：描述绑定Service的intent。
int bindServiceLocked(IApplicationThread caller, IBinder token, Intent service,
String resolvedType, final IServiceConnection connection ...)
throws TransactionTooLargeException {
final ProcessRecord callerApp = mAm.getRecordForAppLOSP(caller);
ActivityServiceConnectionsHolder<ConnectionRecord> activity = null;
int clientLabel = 0;
PendingIntent clientIntent = null;
// 获取 ServiceRecord
ServiceLookupResult res = retrieveServiceLocked(service, instanceName,
isSdkSandboxService, sdkSandboxClientAppUid, sdkSandboxClientAppPackage,
resolvedType, callingPackage, callingPid, callingUid, userId, true, callerFg,
isBindExternal, allowInstant);
ServiceRecord s = res.record;
try {
AppBindRecord b = s.retrieveAppBindingLocked(service, callerApp);
// 用于保存 serviceConnect 信息
ConnectionRecord c = new ConnectionRecord(b, activity,
connection, flags, clientLabel, clientIntent,
callerApp.uid, callerApp.processName, callingPackage, res.aliasComponent);
IBinder binder = connection.asBinder();
// 将connection binder对象添加到map中
s.addConnection(binder, c);
b.connections.add(c);
boolean needOomAdj = false;
// 传入flag是BIND_AUTO_CREATE
if ((flags&Context.BIND_AUTO_CREATE) != 0) {
// Service还没启动，就走启动流程
// bringUpServiceLocked 方法返回null意味着成功启动Service
if (bringUpServiceLocked(s, service.getFlags(), callerFg, false,
permissionsReviewRequired, packageFrozen, true) != null) {
// 启动失败，添加排队
mAm.updateOomAdjPendingTargetsLocked(OomAdjuster.OOM_ADJ_REASON_BIND_SERVICE);
return 0;
}
}
// b.intent.received 表示已接收到绑定Service时返回的binder对象。
if (s.app != null && b.intent.received) {
// 服务已经在运行，可以直接调用connected
//如果客户端尝试启动/连接的是别名，那么需要将别名组件名称传递给客户端。
final ComponentName clientSideComponentName =
res.aliasComponent != null ? res.aliasComponent : s.name;
try {
// 这里的c.conn 即 IServiceConnection对象
c.conn.connected(clientSideComponentName, b.intent.binder, false);
} catch (Exception e) {
}
// 如果这是连接回此绑定的第一个应用， 并且Service已经调用过onUnBind方法
// 则需要调用requestServiceBindingLocked。
if (b.intent.apps.size() == 1 && b.intent.doRebind) {
requestServiceBindingLocked(s, b.intent, callerFg, true);
}
} else if (!b.intent.requested) {
requestServiceBindingLocked(s, b.intent, callerFg, false);
}
} finally {
Binder.restoreCallingIdentity(origId);
}
return 1;
}
4.2 realStartServiceLocked
如startService流程中的分析，bringUpServiceLocked 调用 realStartServiceLocked来启动Service
private void realStartServiceLocked(ServiceRecord r, ProcessRecord app,
IApplicationThread thread ...) throws RemoteException {
// 通知客户端创建service
thread.scheduleCreateService(r, r.serviceInfo,
mAm.compatibilityInfoForPackage(r.serviceInfo.applicationInfo),
app.mState.getReportedProcState());
// 调用Service的onBind方法
requestServiceBindingsLocked(r, execInFg);
.....
}
4.3 requestServiceBindingsLocked
private final void requestServiceBindingsLocked(ServiceRecord r, boolean execInFg)
throws TransactionTooLargeException {
for (int i=r.bindings.size()-1; i>=0; i--) {
IntentBindRecord ibr = r.bindings.valueAt(i);
if (!requestServiceBindingLocked(r, ibr, execInFg, false)) {
break;
}
}
}
4.4 requestServiceBindingLocked
private final boolean requestServiceBindingLocked(ServiceRecord r, IntentBindRecord i,
boolean execInFg, boolean rebind) throws TransactionTooLargeException {
// i.requested:表示是否发送过绑定Service的请求，这里为true
// i.apps.size():表示当前intent绑定Service的应用进程个数
if ((!i.requested || rebind) && i.apps.size() > 0) {
try {
// 启动计时
bumpServiceExecutingLocked(r, execInFg, "bind",
OomAdjuster.OOM_ADJ_REASON_BIND_SERVICE);
// 通知客户端调用bind
r.app.getThread().scheduleBindService(r, i.intent.getIntent(), rebind,
r.app.mState.getReportedProcState());
if (!rebind) {
i.requested = true;
}
i.hasBound = true;
i.doRebind = false;
} catch (TransactionTooLargeException e) {
....
}
}
return true;
}
5. ApplicationThread
代码路径：frameworks\base\core\java\android\app\ActivityThread.java
5.1 scheduleBindService
public final void scheduleBindService(IBinder token, Intent intent,
boolean rebind, int processState) {
updateProcessState(processState, false);
BindServiceData s = new BindServiceData();
s.token = token;
s.intent = intent;
s.rebind = rebind;
sendMessage(H.BIND_SERVICE, s);
}
6. ActivityThread
代码路径：frameworks\base\core\java\android\app\ActivityThread.java
在发送BIND_SERVICE 消息后，最后调用到ActivityThread#handleBindService 方法
6.1 handleBindService
private void handleBindService(BindServiceData data) {
CreateServiceData createData = mServicesData.get(data.token);
Service s = mServices.get(data.token);
try {
if (!data.rebind) {
// 不是重新bind，即没有绑定过，调用onBind方法
IBinder binder = s.onBind(data.intent);
// 将binder对象传给AMS
ActivityManager.getService().publishService(
data.token, data.intent, binder);
} else {
// 调用onRebind方法
s.onRebind(data.intent);
ActivityManager.getService().serviceDoneExecuting(
data.token, SERVICE_DONE_EXECUTING_ANON, 0, 0);
}
} catch (RemoteException ex) {
throw ex.rethrowFromSystemServer();
}
}
7. ActivityManagerService
代码路径：frameworks\base\services\core\java\com\android\server\am\ActivityManagerService.java
7.1 publishService
public void publishService(IBinder token, Intent intent, IBinder service) {
....
synchronized(this) {
mServices.publishServiceLocked((ServiceRecord)token, intent, service);
}
}
8. ActiveServices
代码路径：frameworks\base\services\core\java\com\android\server\am\ActiveServices.java
8.1 publishServiceLocked
void publishServiceLocked(ServiceRecord r, Intent intent, IBinder service) {
final long origId = Binder.clearCallingIdentity();
try {
if (r != null) {
Intent.FilterComparison filter
= new Intent.FilterComparison(intent);
IntentBindRecord b = r.bindings.get(filter);
if (b != null && !b.received) {
b.binder = service; // 保存Service#onBind方法返回的binder对象
b.requested = true;
b.received = true;
ArrayMap<IBinder, ArrayList<ConnectionRecord>> connections = r.getConnections();
for (int conni = connections.size() - 1; conni >= 0; conni--) {
ArrayList<ConnectionRecord> clist = connections.valueAt(conni);
for (int i=0; i<clist.size(); i++) {
ConnectionRecord c = clist.get(i);
if (!filter.equals(c.binding.intent.intent)) {
continue;
}
try {
// 调用ServiceConnection的回调
c.conn.connected(clientSideComponentName, service, false);
} catch (Exception e) {
}
}
}
}
// 移除定时任务等
serviceDoneExecutingLocked(r, mDestroyingServices.contains(r), false, false);
}
} finally {
Binder.restoreCallingIdentity(origId);
}
}
8.2 ConnectionRecord
代码路径：frameworks\base\services\core\java\com\android\server\am\ConnectionRecord.java
该类定义如下
final class ConnectionRecord {
final IServiceConnection conn; // The client connection.
.....
}
这里的IServiceConnection 即我们在bindService的时候，生成的ServiceDispatcher中内部mIServiceConnection 变量
9. LoadedApk
代码路径：frameworks\base\core\java\android\app\LoadedApk.java
9.1 InnerConnection
private static class InnerConnection extends IServiceConnection.Stub {
@UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
final WeakReference<LoadedApk.ServiceDispatcher> mDispatcher;
InnerConnection(LoadedApk.ServiceDispatcher sd) {
mDispatcher = new WeakReference<LoadedApk.ServiceDispatcher>(sd);
}
public void connected(ComponentName name, IBinder service, boolean dead)
throws RemoteException {
LoadedApk.ServiceDispatcher sd = mDispatcher.get();
if (sd != null) {
sd.connected(name, service, dead);
}
}
}
9.2 ServiceDispatcher
connect方法中会做切线程的动作，RunConnection 内部实际是调用到doConnected 方法。
static final class ServiceDispatcher {
public void connected(ComponentName name, IBinder service, boolean dead) {
if (mActivityExecutor != null) {
mActivityExecutor.execute(new RunConnection(name, service, 0, dead));
} else if (mActivityThread != null) {
mActivityThread.post(new RunConnection(name, service, 0, dead));
} else {
doConnected(name, service, dead);
}
}
}
9.3 doConnected
public void doConnected(ComponentName name, IBinder service, boolean dead) {
ServiceDispatcher.ConnectionInfo old;
ServiceDispatcher.ConnectionInfo info;
synchronized (this) {
old = mActiveConnections.get(name)
if (service != null) {
info = new ConnectionInfo();
info.binder = service;
info.deathMonitor = new DeathMonitor(name, service);
try {
// 监听bind的死亡回调
service.linkToDeath(info.deathMonitor, 0);
mActiveConnections.put(name, info);
} catch (RemoteException e) {
mActiveConnections.remove(name);
return;
}
} else {
// The named service is being disconnected... clean up.
mActiveConnections.remove(name);
}
if (old != null) {
old.binder.unlinkToDeath(old.deathMonitor, 0);
}
}
// 如果有老的服务，那就通知断开
if (old != null) {
mConnection.onServiceDisconnected(name);
}
if (dead) {
// 如果service端已经dead，就调用onBindingDied
mConnection.onBindingDied(name);
} else {
// 通知service已经连接上，并且远程服务返回的bind对象不为null
if (service != null) {
mConnection.onServiceConnected(name, service);
} else {
// 远程服务返回null的bind对象，
mConnection.onNullBinding(name);
}
}
}
总结
如果当前应用是第一个与Service绑定，并且Service已经调用过unUnBind方法，则会调用Service的onRebind方法文章来源：https://www.toymoban.com/news/detail-514099.html
对应的uml图如下
文章来源地址https://www.toymoban.com/news/detail-514099.html
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