Step 7. ActivityStack.startActivityMayWait
这个函数定义在frameworks/base/services/java/com/Android/server/am/ActivityStack.java文件中：
public class ActivityStack { ...... final int startActivityMayWait(IApplicationThread caller, Intent intent, String resolvedType, Uri[] grantedUriPermissions, int grantedMode, IBinder resultTo, String resultWho, int requestCode, boolean onlyIfNeeded, boolean debug, WaitResult outResult, Configuration config) { ...... boolean componentSpecified = intent.getComponent() != null; // Don't modify the client's object! intent = new Intent(intent); // Collect information about the target of the Intent. ActivityInfo aInfo; try { ResolveInfo rInfo = AppGlobals.getPackageManager().resolveIntent( intent, resolvedType, PackageManager.MATCH_DEFAULT_ONLY | ActivityManagerService.STOCK_PM_FLAGS); aInfo = rInfo != null ? rInfo.activityInfo : null; } catch (RemoteException e) { ...... } if (aInfo != null) { // Store the found target back into the intent, because now that // we have it we never want to do this again. For example, if the // user navigates back to this point in the history, we should // always restart the exact same activity. intent.setComponent(new ComponentName( aInfo.applicationInfo.packageName, aInfo.name)); ...... } synchronized (mService) { int callingPid; int callingUid; if (caller == null) { ...... } else { callingPid = callingUid = -1; } mConfigWillChange = config != null && mService.mConfiguration.diff(config) != 0; ...... if (mMainStack && aInfo != null && (aInfo.applicationInfo.flags&ApplicationInfo.FLAG_CANT_SAVE_STATE) != 0) { ...... } int res = startActivityLocked(caller, intent, resolvedType, grantedUriPermissions, grantedMode, aInfo, resultTo, resultWho, requestCode, callingPid, callingUid, onlyIfNeeded, componentSpecified); if (mConfigWillChange && mMainStack) { ...... } ...... if (outResult != null) { ...... } return res; } } ...... }
注意，从Step 6传下来的参数outResult和config均为null，此外，表达式(aInfo.applicationInfo.flags&ApplicationInfo.FLAG_CANT_SAVE_STATE) != 0为false，因此，这里忽略了无关代码。下面语句对参数intent的内容进行解析，得到MainActivity的相关信息，保存在aInfo变量中：
ActivityInfo aInfo; try { ResolveInfo rInfo = AppGlobals.getPackageManager().resolveIntent( intent, resolvedType, PackageManager.MATCH_DEFAULT_ONLY | ActivityManagerService.STOCK_PM_FLAGS); aInfo = rInfo != null ? rInfo.activityInfo : null; } catch (RemoteException e) { ...... }
解析之后，得到的aInfo.applicationInfo.packageName的值为"shy.luo.activity"，aInfo.name的值为"shy.luo.activity.MainActivity"，这是在这个实例的配置文件AndroidManifest.xml里面配置的。此外，函数开始的地方调用intent.getComponent()函数的返回值不为null，因此，这里的componentSpecified变量为true。
接下去就调用startActivityLocked进一步处理了。
Step 8. ActivityStack.startActivityLocked
这个函数定义在frameworks/base/services/java/com/android/server/am/ActivityStack.java文件中：
public class ActivityStack { ...... final int startActivityLocked(IApplicationThread caller, Intent intent, String resolvedType, Uri[] grantedUriPermissions, int grantedMode, ActivityInfo aInfo, IBinder resultTo, String resultWho, int requestCode, int callingPid, int callingUid, boolean onlyIfNeeded, boolean componentSpecified) { int err = START_SUCCESS; ProcessRecord callerApp = null; if (caller != null) { callerApp = mService.getRecordForAppLocked(caller); if (callerApp != null) { callingPid = callerApp.pid; callingUid = callerApp.info.uid; } else { ...... } } ...... ActivityRecord sourceRecord = null; ActivityRecord resultRecord = null; if (resultTo != null) { int index = indexOfTokenLocked(resultTo); ...... if (index >= 0) { sourceRecord = (ActivityRecord)mHistory.get(index); if (requestCode >= 0 && !sourceRecord.finishing) { ...... } } } int launchFlags = intent.getFlags(); if ((launchFlags&Intent.FLAG_ACTIVITY_FORWARD_RESULT) != 0 && sourceRecord != null) { ...... } if (err == START_SUCCESS && intent.getComponent() == null) { ...... } if (err == START_SUCCESS && aInfo == null) { ...... } if (err != START_SUCCESS) { ...... } ...... ActivityRecord r = new ActivityRecord(mService, this, callerApp, callingUid, intent, resolvedType, aInfo, mService.mConfiguration, resultRecord, resultWho, requestCode, componentSpecified); ...... return startActivityUncheckedLocked(r, sourceRecord, grantedUriPermissions, grantedMode, onlyIfNeeded, true); } ...... }
从传进来的参数caller得到调用者的进程信息，并保存在callerApp变量中，这里就是Launcher应用程序的进程信息了。前面说过，参数resultTo是Launcher这个Activity里面的一个Binder对象，通过它可以获得Launcher这个Activity的相关信息，保存在sourceRecord变量中。
再接下来，创建即将要启动的Activity的相关信息，并保存在r变量中：
ActivityRecord r = new ActivityRecord(mService, this, callerApp, callingUid, intent, resolvedType, aInfo, mService.mConfiguration, resultRecord, resultWho, requestCode, componentSpecified);
接着调用startActivityUncheckedLocked函数进行下一步操作。