启动过程源码分析
官方案例
image.png
getContentResolver源码
@Override
public ContentResolver getContentResolver() {
//mContentResolver实际是ApplicationContentResolver
return mContentResolver;
}
public final @Nullable Cursor query(final @RequiresPermission.Read @NonNull Uri uri,
@Nullable String[] projection, @Nullable Bundle queryArgs,
@Nullable CancellationSignal cancellationSignal) {
Preconditions.checkNotNull(uri, "uri");
//返回IContentProvider 对象
IContentProvider unstableProvider = acquireUnstableProvider(uri);
try {
try {
qCursor = unstableProvider.query(mPackageName, uri, projection,
queryArgs, remoteCancellationSignal);
}
}
}
查看acquireUnstableProvider源码
public final IContentProvider acquireUnstableProvider(Uri uri) {
//检查scheme是否等于content
if (!SCHEME_CONTENT.equals(uri.getScheme())) {
return null;
}
String auth = uri.getAuthority();
if (auth != null) {
return acquireUnstableProvider(mContext, uri.getAuthority());
}
return null;
}
//实现类实际是ContextImpl类的ApplicationContentResolver
protected abstract IContentProvider acquireUnstableProvider(Context c, String name);
private static final class ApplicationContentResolver extends ContentResolver {
@Override
protected IContentProvider acquireUnstableProvider(Context c, String auth) {
//mMainThread实际是ActivityThread
return mMainThread.acquireProvider(c,
ContentProvider.getAuthorityWithoutUserId(auth),
resolveUserIdFromAuthority(auth), false);
}
}
public final IContentProvider acquireProvider(
Context c, String auth, int userId, boolean stable) {
final IContentProvider provider = acquireExistingProvider(c, auth, userId, stable);
if (provider != null) {
//判断provider是否为空
return provider;
}
ContentProviderHolder holder = null;
try {
synchronized (getGetProviderLock(auth, userId)) {
//实际最终会走到AMS的getContentProvider方法
holder = ActivityManager.getService().getContentProvider(
getApplicationThread(), auth, userId, stable);
}
} catch (RemoteException ex) {
throw ex.rethrowFromSystemServer();
}
if (holder == null) {
Slog.e(TAG, "Failed to find provider info for " + auth);
return null;
}
//返回的ContentProvider相关的数据存储在mProviderMap中
holder = installProvider(c, holder, holder.info,
true /*noisy*/, holder.noReleaseNeeded, stable);
return holder.provider;
}
@Override
public final ContentProviderHolder getContentProvider(
IApplicationThread caller, String name, int userId, boolean stable) {
enforceNotIsolatedCaller("getContentProvider");
return getContentProviderImpl(caller, name, null, stable, userId);
}
private ContentProviderHolder getContentProviderImpl(IApplicationThread caller,
String name, IBinder token, boolean stable, int userId) {
if (i >= N) {
try {
//获取ContentProvider的进程信息
ProcessRecord proc = getProcessRecordLocked(
cpi.processName, cpr.appInfo.uid, false);
if (proc != null && proc.thread != null && !proc.killed) {
//如果已经启动就会走到这里
if (!proc.pubProviders.containsKey(cpi.name)) {
checkTime(startTime, "getContentProviderImpl: scheduling install");
proc.pubProviders.put(cpi.name, cpr);
try {
proc.thread.scheduleInstallProvider(cpi);
} catch (RemoteException e) {
}
}
} else {
//如果没有启动则进入这里
proc = startProcessLocked(cpi.processName,
cpr.appInfo, false, 0, "content provider",
new ComponentName(cpi.applicationInfo.packageName,
cpi.name), false, false, false);
}
cpr.launchingApp = proc;
mLaunchingProviders.add(cpr);
} finally {
Binder.restoreCallingIdentity(origId);
}
}
}
刚开始肯定是没有创建进程，startProcessLocked最后走到的ActivityThread的main方法
public static void main(String[] args) {
//创建looper
Looper.prepareMainLooper();
ActivityThread thread = new ActivityThread();
thread.attach(false, startSeq);
if (sMainThreadHandler == null) {
sMainThreadHandler = thread.getHandler();
}
if (false) {
Looper.myLooper().setMessageLogging(new
LogPrinter(Log.DEBUG, "ActivityThread"));
}
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
//消息循环
Looper.loop();
throw new RuntimeException("Main thread loop unexpectedly exited");
}
private void attach(boolean system) {
//得到AMS服务
final IActivityManager mgr = ActivityManagerNative.getDefault();
try {
//调用AMS的attachApplication方法
mgr.attachApplication(mAppThread);
} catch (RemoteException ex) {
throw ex.rethrowFromSystemServer();
}
}
AMS启动ContentProvider
@Override
public final void attachApplication(IApplicationThread thread, long startSeq) {
synchronized (this) {
int callingPid = Binder.getCallingPid();
final int callingUid = Binder.getCallingUid();
final long origId = Binder.clearCallingIdentity();
attachApplicationLocked(thread, callingPid, callingUid, startSeq);
Binder.restoreCallingIdentity(origId);
}
}
private final boolean attachApplicationLocked(IApplicationThread thread,
int pid, int callingUid, long startSeq) {
thread.bindApplication(processName, appInfo, providers,
app.instr.mClass,
profilerInfo, app.instr.mArguments,
app.instr.mWatcher,
app.instr.mUiAutomationConnection, testMode,
mBinderTransactionTrackingEnabled, enableTrackAllocation,
isRestrictedBackupMode || !normalMode, app.persistent,
new Configuration(getGlobalConfiguration()), app.compat,
getCommonServicesLocked(app.isolated),
mCoreSettingsObserver.getCoreSettingsLocked(),
buildSerial, isAutofillCompatEnabled);
}
从上面传值我们可以知道thread实际是ApplicationThread
private class ApplicationThread extends IApplicationThread.Stub {
public final void bindApplication(String processName, ApplicationInfo appInfo,
List<ProviderInfo> providers, ComponentName instrumentationName,
ProfilerInfo profilerInfo, Bundle instrumentationArgs,
IInstrumentationWatcher instrumentationWatcher,
sendMessage(H.BIND_APPLICATION, data);
}
}
case BIND_APPLICATION:
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "bindApplication");
AppBindData data = (AppBindData)msg.obj;
handleBindApplication(data);
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
break;
private void handleBindApplication(AppBindData data) {
//创建ContextImpl对象
final ContextImpl appContext = ContextImpl.createAppContext(this, data.info);
if (ii != null) {
try {
final ClassLoader cl = instrContext.getClassLoader();
//通过反射创建mInstrumentation 对象
mInstrumentation = (Instrumentation)
cl.loadClass(data.instrumentationName.getClassName()).newInstance();
} catch (Exception e) {
}
final ComponentName component = new ComponentName(ii.packageName, ii.name);
mInstrumentation.init(this, instrContext, appContext, component,
data.instrumentationWatcher, data.instrumentationUiAutomationConnection);
} else {
mInstrumentation = new Instrumentation();
mInstrumentation.basicInit(this);
}
//创建application
app = data.info.makeApplication(data.restrictedBackupMode, null);
if (!data.restrictedBackupMode) {
if (!ArrayUtils.isEmpty(data.providers)) {
//启动contentProviders
installContentProviders(app, data.providers);
mH.sendEmptyMessageDelayed(H.ENABLE_JIT, 10*1000);
}
}
try {
//调用Application的onCreate方法
mInstrumentation.onCreate(data.instrumentationArgs);
}
}
}
我们会发现contentProvider所在的应用程序进程实在Application的onCreate之前调用的。我们继续分析installContentProviders的源码
private void installContentProviders(
Context context, List<ProviderInfo> providers) {
final ArrayList<ContentProviderHolder> results = new ArrayList<>();
for (ProviderInfo cpi : providers) {
ContentProviderHolder cph = installProvider(context, null, cpi,
false /*noisy*/, true /*noReleaseNeeded*/, true /*stable*/);
}
try {
ActivityManager.getService().publishContentProviders(
getApplicationThread(), results);
} catch (RemoteException ex) {
throw ex.rethrowFromSystemServer();
}
}
private ContentProviderHolder installProvider(Context context,
ContentProviderHolder holder, ProviderInfo info,
boolean noisy, boolean noReleaseNeeded, boolean stable) {
ContentProvider localProvider = null;
IContentProvider provider;
if (holder == null || holder.provider == null) {
//创建context
try {
final java.lang.ClassLoader cl = c.getClassLoader();
//创建localProvider对象
provider = localProvider.getIContentProvider();
if (provider == null) {
return null;
}
localProvider.attachInfo(c, info);
}
return retHolder;
}
public void attachInfo(Context context, ProviderInfo info) {
attachInfo(context, info, false);
}
private void attachInfo(Context context, ProviderInfo info, boolean testing) {
//调用ContentProvider的onCreate生命周期
ContentProvider.this.onCreate();
}
}
ContentProvider的启动过程.png
网友评论