bindService的调用流程
使用bindService去调用service，如果有多个客户端调用，onBind方法只会被调用一次，由于bindService嗲处理中，AMS是一个中间商，猜测这个处理也是AMS里进行的，这里我们再看看bindService的调用流程
public class ContextWrapper extends Context {
Context mBase;
public ContextWrapper(Context base) {
mBase = base;
}
public boolean bindService(Intent service, ServiceConnection conn,
int flags) {
return mBase.bindService(service, conn, flags);
}
ContextImpl.java
// bindService
@Override
public boolean bindService(Intent service, ServiceConnection conn, int flags) {
warnIfCallingFromSystemProcess();
return bindServiceCommon(service, conn, flags, Process.myUserHandle());
}
// bindServiceCommon
private boolean bindServiceCommon(Intent service, ServiceConnection conn, int flags, UserHandle user) {
IServiceConnection sd;
...
//包装ServiceConnection
sd = mPackageInfo.getServiceDispatcher(conn, getOuterContext(),
mMainThread.getHandler(), flags);
...
int res = ActivityManagerNative.getDefault().bindService(
mMainThread.getApplicationThread(), getActivityToken(), service,
service.resolveTypeIfNeeded(getContentResolver()),
sd, flags, getOpPackageName(), user.getIdentifier());
...
}
这里是通过binder和AMS进行通信，一次binder调用
ActivityManagerNative.java
private static final Singleton
protected IActivityManager create() {
IBinder b = ServiceManager.getService("activity");
if (false) {
Log.v("ActivityManager", "default service binder = " + b);
}
IActivityManager am = asInterface(b);
if (false) {
Log.v("ActivityManager", "default service = " + am);
}
return am;
}
};
}
static public IActivityManager asInterface(IBinder obj) {
if (obj == null) {
return null;
}
IActivityManager in =
(IActivityManager)obj.queryLocalInterface(descriptor);
if (in != null) {
return in;
}
return new ActivityManagerProxy(obj);
}
public abstract class Singleton
private T mInstance;
protected abstract T create();
public final T get() {
synchronized (this) {
if (mInstance == null) {
mInstance = create();
}
return mInstance;
}
}
}
即包装ServiceManager.getService("activity");
继续查看bindServiceCommon方法
private boolean bindServiceCommon(Intent service, ServiceConnection conn, int flags, Handler
handler, UserHandle user) {
IServiceConnection sd;
if (conn == null) {
throw new IllegalArgumentException("connection is null");
}
if (mPackageInfo != null) {
sd = mPackageInfo.getServiceDispatcher(conn, getOuterContext(), handler, flags);
} else {
throw new RuntimeException("Not supported in system context");
}
validateServiceIntent(service);
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);
int res = ActivityManagerNative.getDefault().bindService(
mMainThread.getApplicationThread(), getActivityToken(), service,
service.resolveTypeIfNeeded(getContentResolver()),
sd, flags, getOpPackageName(), user.getIdentifier());
这个sd是怎么来的呢
ServiceDispatcher用来包装ServiceConnection
创建binder实体对象，用来响应回调
LoadedApk.java
public final IServiceConnection getServiceDispatcher(ServiceConnection c,
Context context, Handler handler, int flags) {
synchronized (mServices) {
LoadedApk.ServiceDispatcher sd = null;
ArrayMap
if (map != null) {
sd = map.get(c);
}
if (sd == null) {
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);
}
return sd.getIServiceConnection();
}
}
ServiceDispatcher(ServiceConnection conn,
Context context, Handler activityThread, int flags) {
mIServiceConnection = new InnerConnection(this);
mConnection = conn;
mContext = context;
mActivityThread = activityThread;
mLocation = new ServiceConnectionLeaked(null);
mLocation.fillInStackTrace();
mFlags = flags;
}
InnerConnection用来进行binder通信
private static class InnerConnection extends IServiceConnection.Stub {
final WeakReference
InnerConnection(LoadedApk.ServiceDispatcher sd) {
mDispatcher = new WeakReference
}
public void connected(ComponentName name, IBinder service) throws RemoteException {
LoadedApk.ServiceDispatcher sd = mDispatcher.get();
if (sd != null) {
sd.connected(name, service);
}
}
}
AMS端作为Proxy进行调用connected方法
IServiceConnection.Stub的定义
vi out/target/common/obj/JAVA_LIBRARIES/framework_intermediates/src/core/java/android/app/IServiceConnection.java
/*
* This file is auto-generated. DO NOT MODIFY.
* Original file: frameworks/base/core/java/android/app/IServiceConnection.aidl
*/
package android.app;
/** @hide */
public interface IServiceConnection extends android.os.IInterface
{
/** Local-side IPC implementation stub class. */
public static abstract class Stub extends android.os.Binder implements android.app.IServiceConnection
{
@Override public boolean onTransact(int code, android.os.Parcel data, android.os.Parcel reply, int flags) throws android.os.RemoteException
{
switch (code)
{
case INTERFACE_TRANSACTION:
{
reply.writeString(DESCRIPTOR);
return true;
}
case TRANSACTION_connected:
{
data.enforceInterface(DESCRIPTOR);
android.content.ComponentName _arg0;
if ((0!=data.readInt())) {
_arg0 = android.content.ComponentName.CREATOR.createFromParcel(data);
}
else {
_arg0 = null;
}
android.os.IBinder _arg1;
_arg1 = data.readStrongBinder();
this.connected(_arg0, _arg1);
return true;
}
}
return super.onTransact(code, data, reply, flags);
}
private static class Proxy implements android.app.IServiceConnection
{
private android.os.IBinder mRemote;
Proxy(android.os.IBinder remote)
AMS通过调用传入的proxy来和client端进行交互
ActivityManagerService中有方法
public void publishService(IBinder token, Intent intent, IBinder service) {
// Refuse possible leaked file descriptors
if (intent != null && intent.hasFileDescriptors() == true) {
throw new IllegalArgumentException("File descriptors passed in Intent");
}
synchronized(this) {
if (!(token instanceof ServiceRecord)) {
throw new IllegalArgumentException("Invalid service token");
}
mServices.publishServiceLocked((ServiceRecord)token, intent, service);
}
}
ActiveServices.java
void publishServiceLocked(ServiceRecord r, Intent intent, IBinder service) {
...
for (int conni=r.connections.size()-1; conni>=0; conni--) {
ArrayList
for (int i=0; i ConnectionRecord c = clist.get(i); ... try { //binder调用，AMS调用client的方法，把service的binder传过去 c.conn.connected(r.name, service); } catch (Exception e) { Slog.w(TAG, "Failure sending service " + r.name + " to connection " + c.conn.asBinder() + " (in " + c.binding.client.processName + ")", e); } } } ... } ConnectionRecord.java final class ConnectionRecord { final AppBindRecord binding; // The application/service binding. final ActivityRecord activity; // If non-null, the owning activity. final IServiceConnection conn; // The client connection. AMS中 public int bindService(IApplicationThread caller, IBinder token, Intent service, String resolvedType, IServiceConnection connection, int flags, String callingPackage, int userId) throws TransactionTooLargeException { enforceNotIsolatedCaller("bindService"); // Refuse possible leaked file descriptors if (service != null && service.hasFileDescriptors() == true) { throw new IllegalArgumentException("File descriptors passed in Intent"); } if (callingPackage == null) { throw new IllegalArgumentException("callingPackage cannot be null"); } synchronized(this) { return mServices.bindServiceLocked(caller, token, service, resolvedType, connection, flags, callingPackage, userId); } } 在ActivityManagerService.java中有定义 final ActiveServices mServices; ActiveServices.java中 bindServiceLocked bringUpServiceLocked public final class ActiveServices { private final void realStartServiceLocked(ServiceRecord r, ProcessRecord app, boolean execInFg) throws RemoteException { ... r.app = app; ... app.thread.scheduleCreateService(r, r.serviceInfo, mAm.compatibilityInfoForPackageLocked(r.serviceInfo.applicationInfo), app.repProcState); r.postNotification(); ... // requestServiceBindingsLocked(r, execInFg); updateServiceClientActivitiesLocked(app, null, true); ... } private final boolean requestServiceBindingLocked(ServiceRecord r, IntentBindRecord i, boolean execInFg, boolean rebind) throws TransactionTooLargeException { if (r.app == null || r.app.thread == null) { // If service is not currently running, can't yet bind. return false; } if ((!i.requested || rebind) && i.apps.size() > 0) { try { bumpServiceExecutingLocked(r, execInFg, "bind"); r.app.forceProcessStateUpTo(ActivityManager.PROCESS_STATE_SERVICE); r.app.thread.scheduleBindService(r, i.intent.getIntent(), rebind, r.app.repProcState); if (!rebind) { i.requested = true; } i.hasBound = true; i.doRebind = false; } catch (TransactionTooLargeException e) { … … } } return true; } final class ProcessRecord { IApplicationThread thread; 这里是binder调用 在启动应用的过程中，通过对AMS的binder调用，传给了AMS一个ApplicationThread的proxy对象。 public abstract class ApplicationThreadNative extends Binder implements IApplicationThread { /** ActivityThread.java中有内部类 private class ApplicationThread extends ApplicationThreadNative { private static final String DB_INFO_FORMAT = " %8s %8s %14s %14s %s"; 调用到ApplicationThread的 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); } 处理该消息时调用ActivityThread的 private void handleBindService(BindServiceData data) { Service s = mServices.get(data.token); if (s != null) { try { data.intent.setExtrasClassLoader(s.getClassLoader()); data.intent.prepareToEnterProcess(); try { if (!data.rebind) { IBinder binder = s.onBind(data.intent); ActivityManagerNative.getDefault().publishService( data.token, data.intent, binder); } else { s.onRebind(data.intent); ActivityManagerNative.getDefault().serviceDoneExecuting( data.token, SERVICE_DONE_EXECUTING_ANON, 0, 0); } ensureJitEnabled(); } catch (RemoteException ex) { throw ex.rethrowFromSystemServer(); } } catch (Exception e) { } } } 在server进程中，通过调用AMS服务publishService把binder对象传给AMS