1、Activity的啟動方式
在android中，啟動activity的方式有很多種，比如通過launcher來啟動，比如通過調用activity的startActivity()方法來啟動，adb shell 命令來啟動等等，這里只簡單過一下點擊桌面啟動Activity的流程。
2、Launcher.java中啟動activity
launcher是activity的一個子類，關于launcher原碼分析這里暫時不考慮，從點擊shortcut開始來分析。
/**
* Launches the intent referred by the clicked shortcut.
*
* @param v The view representing the clicked shortcut.
*/
public void onClick(View v) {
Object tag = v.getTag();
if (tag instanceof ApplicationInfo) {
// Open shortcut
final Intent intent = ((ApplicationInfo) tag).intent;
startActivitySafely(intent);
} else if (tag instanceof FolderInfo) {
handleFolderClick((FolderInfo) tag);
}
}
void startActivitySafely(Intent intent) {
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
try {
startActivity(intent);//
} catch (ActivityNotFoundException e) {
Toast.makeText(this, R.string.activity_not_found, Toast.LENGTH_SHORT).show();
} catch (SecurityException e) {
Toast.makeText(this, R.string.activity_not_found, Toast.LENGTH_SHORT).show();
e(LOG_TAG, "Launcher does not have the permission to launch " + intent +
". Make sure to create a MAIN intent-filter for the corresponding activity " +
"or use the exported attribute for this activity.", e);
}
}
3、Activity.startActivity()
public void startActivity(Intent intent) {
this.startActivity(intent, null);
}
public void startActivity(Intent intent, @Nullable Bundle options) {
if (options != null) {
startActivityForResult(intent, -1, options);
} else {
// Note we want to go through this call for compatibility with
// applications that may have overridden the method.
startActivityForResult(intent, -1);
}
}
4、Activity.startActivityForResult()
public void startActivityForResult(Intent intent, int requestCode, @Nullable Bundle options) {
if (mParent == null) {// 應用的第一個Activity
Instrumentation.ActivityResult ar =
mInstrumentation.execStartActivity(
this, mMainThread.getApplicationThread(), mToken, this,
intent, requestCode, options);
if (ar != null) {
mMainThread.sendActivityResult(
mToken, mEmbeddedID, requestCode, ar.getResultCode(),
ar.getResultData());
}
if (requestCode >= 0) {
// If this start is requesting a result, we can avoid making
// the activity visible until the result is received. Setting
// this code during onCreate(Bundle savedInstanceState) or onResume() will keep the
// activity hidden during this time, to avoid flickering.
// This can only be done when a result is requested because
// that guarantees we will get information back when the
// activity is finished, no matter what happens to it.
mStartedActivity = true;
}
cancelInputsAndStartExitTransition(options);
// TODO Consider clearing/flushing other event sources and events for child windows.
} else {
if (options != null) {
mParent.startActivityFromChild(this, intent, requestCode, options);
} else {
// Note we want to go through this method for compatibility with
// existing applications that may have overridden it.
mParent.startActivityFromChild(this, intent, requestCode);
}
}
}
不管mParent是否為null，最終都是調用mInstrumentation.execStartActivity 來啟動另外Activity的。
public ActivityResult execStartActivity(
Context who, IBinder contextThread/**/, IBinder token/**/, Activity target,
Intent intent, int requestCode, Bundle options) {
// 調用者是哪一個
IApplicationThread whoThread = (IApplicationThread) contextThread;
Uri referrer = target != null ? target.onProvideReferrer() : null;
if (referrer != null) {
intent.putExtra(Intent.EXTRA_REFERRER, referrer);
}
if (mActivityMonitors != null) {// 對啟動的activity進行檢查
synchronized (mSync) {
final int N = mActivityMonitors.size();
for (int i=0; i<N; i++) {
final ActivityMonitor am = mActivityMonitors.get(i);
if (am.match(who, null, intent)) {
am.mHits++;
if (am.isBlocking()) {
return requestCode >= 0 ? am.getResult() : null;
}
break;
}
}
}
}
try {
intent.migrateExtraStreamToClipData();
intent.prepareToLeaveProcess();
// 調用AMS.startActivity
int result = ActivityManagerNative.getDefault()
.startActivity(whoThread, who.getBasePackageName(), intent,
intent.resolveTypeIfNeeded(who.getContentResolver()),
token, target != null ? target.mEmbeddedID : null,
requestCode, 0, null, options);
checkStartActivityResult(result, intent);
} catch (RemoteException e) {
throw new RuntimeException("Failure from system", e);
}
return null;
}
Client端的流程到這里就已經結束了，后續就跳轉到Server端了，在分析Server端之前，先理一下幾個類的關系：
ActivityRecord：Activity相關的信息都保存在這個對象中；
ActivityStask:這是一個獨立的棧，用來保存和管理ActivityRecord；
ActivityStackSupervisor：用來調度管理ActivityStask
QQ截圖20160815165610.png
5 ActivityManagerService.startActivity()
@Override
public final int startActivity(IApplicationThread caller, String callingPackage,
Intent intent, String resolvedType, IBinder resultTo, String resultWho, int requestCode,
int startFlags, ProfilerInfo profilerInfo, Bundle options) {
return startActivityAsUser(caller, callingPackage, intent, resolvedType, resultTo,
resultWho, requestCode, startFlags, profilerInfo, options,
UserHandle.getCallingUserId());
}
@Override
public final int startActivityAsUser(IApplicationThread caller, String callingPackage,
Intent intent, String resolvedType, IBinder resultTo, String resultWho, int requestCode,
int startFlags, ProfilerInfo profilerInfo, Bundle options, int userId) {
// 是否有權限啟動activity
enforceNotIsolatedCaller("startActivity");
userId = handleIncomingUser(Binder.getCallingPid(), Binder.getCallingUid(), userId,
false, ALLOW_FULL_ONLY, "startActivity", null);
// TODO: Switch to user app stacks here.
return mStackSupervisor.startActivityMayWait(caller, -1, callingPackage, intent,
resolvedType, null, null, resultTo, resultWho, requestCode, startFlags,
profilerInfo, null, null, options, false, userId, null, null);
}
6 ActivityStackSupervisor.startActivityMayWait()
final int startActivityMayWait(IApplicationThread caller, int callingUid,
String callingPackage, Intent intent, String resolvedType,
IVoiceInteractionSession voiceSession, IVoiceInteractor voiceInteractor,
IBinder resultTo, String resultWho, int requestCode, int startFlags,
ProfilerInfo profilerInfo, WaitResult outResult, Configuration config,
Bundle options, boolean ignoreTargetSecurity, int userId,
IActivityContainer iContainer, TaskRecord inTask) {
// Refuse possible leaked file descriptors
if (intent != null && intent.hasFileDescriptors()) {
throw new IllegalArgumentException("File descriptors passed in Intent");
}
boolean componentSpecified = intent.getComponent() != null;
// Don't modify the client's object!
intent = new Intent(intent);
// Collect information about the target of the Intent.
// 從PMS中查找和intent匹配的activity信息
ActivityInfo aInfo =
resolveActivity(intent, resolvedType, startFlags, profilerInfo, userId);
ActivityContainer container = (ActivityContainer)iContainer;
synchronized (mService) {
// 調用者的uid和pid
if (container != null && container.mParentActivity != null &&
container.mParentActivity.state != RESUMED) {
// Cannot start a child activity if the parent is not resumed.
return ActivityManager.START_CANCELED;
}
final int realCallingPid = Binder.getCallingPid();
final int realCallingUid = Binder.getCallingUid();
int callingPid;
if (callingUid >= 0) {
callingPid = -1;
} else if (caller == null) {
callingPid = realCallingPid;
callingUid = realCallingUid;
} else {
callingPid = callingUid = -1;
}
// 一個activity棧，用來管理里面的activities，因為activity由activityrecord來存儲，所以ActivityStack 管理的其實是ActivityRecord.
final ActivityStack stack;
if (container == null || container.mStack.isOnHomeDisplay()) {
stack = mFocusedStack;
} else {
stack = container.mStack;
}
stack.mConfigWillChange = config != null && mService.mConfiguration.diff(config) != 0;
if (DEBUG_CONFIGURATION) Slog.v(TAG_CONFIGURATION,
"Starting activity when config will change = " + stack.mConfigWillChange);
final long origId = Binder.clearCallingIdentity();
//......
int res = startActivityLocked(caller, intent, resolvedType, aInfo,
voiceSession, voiceInteractor, resultTo, resultWho,
requestCode, callingPid, callingUid, callingPackage,
realCallingPid, realCallingUid, startFlags, options, ignoreTargetSecurity,
componentSpecified, null, container, inTask);
Binder.restoreCallingIdentity(origId);
if (stack.mConfigWillChange) {
// If the caller also wants to switch to a new configuration,
// do so now. This allows a clean switch, as we are waiting
// for the current activity to pause (so we will not destroy
// it), and have not yet started the next activity.
mService.enforceCallingPermission(android.Manifest.permission.CHANGE_CONFIGURATION,
"updateConfiguration()");
stack.mConfigWillChange = false;
if (DEBUG_CONFIGURATION) Slog.v(TAG_CONFIGURATION,
"Updating to new configuration after starting activity.");
mService.updateConfigurationLocked(config, null, false, false);
}
if (outResult != null) {
outResult.result = res;
if (res == ActivityManager.START_SUCCESS) {
mWaitingActivityLaunched.add(outResult);
do {
try {
mService.wait();
} catch (InterruptedException e) {
}
} while (!outResult.timeout && outResult.who == null);
} else if (res == ActivityManager.START_TASK_TO_FRONT) {
// 記錄一個Activity(這個activity是Android中的四大組件，而非PMS解析APK得到的那個activity)的所有信息,由ActivityStack進行管理
ActivityRecord r = stack.topRunningActivityLocked(null);
if (r.nowVisible && r.state == RESUMED) {
outResult.timeout = false;
outResult.who = new ComponentName(r.info.packageName, r.info.name);
outResult.totalTime = 0;
outResult.thisTime = 0;
} else {
outResult.thisTime = SystemClock.uptimeMillis();
mWaitingActivityVisible.add(outResult);
do {
try {
mService.wait();
} catch (InterruptedException e) {
}
} while (!outResult.timeout && outResult.who == null);
}
}
}
return res;
}
}
7 ActivityStackSupervisor.startActivityLocked()
該函數主要工作是檢查調用者Launcher權限，調用者是否需要返回結果，檢查目標Intent是否正確，檢查目標activity是否存在，檢查是否具有調用startActivity權限；檢查通過后創建目標activity對應的activityrecord，然后交給startActivityUncheckedLocked繼續處理。
8 ActivityStackSupervisor.startActivityUncheckedLocked()
該方法主要工作：
1）根據目標Activity的LaunchMode決定是否需要建立新的Task
2）檢查是否有可重用的Task和Activity
3）查找是否具有可重用的Activity（ActivityRecord）
4）TaskRecord和Activity關聯起來
5）工作繼續交由ActivityStack.startActivityLocked()來完成。
9 ActivityStack.startActivityLocked()
該方法的主要工作是：根據要啟動的Activity所在的Task是否存在來決定是從原有的Task隊列中找還是新建一個task，然后更改該task在任務隊列的位置，準備Activity啟動動畫，然后將工作交給ActivityStackSupervisor.resumeTopActivitiesLocked();
10 ActivityStackSupervisor.resumeTopActivitiesLocked()
判斷棧頂是否有需要顯示的Activity，暫停所有處于棧頂的Activity（調用ActivityStack.resumeTopActivityLocked()方法）
11 ActivityStack.resumeTopActivityInnerLocked()
調用ActivityStackSupervisor.pauseBackStacks()暫停所有的Activity，調用ActivityStackSupervisor.startSpecificActivityLocked(next, true, true)來啟動目標Activity。
12 ActivityStackSupervisor.startSpecificActivityLocked()
void startSpecificActivityLocked(ActivityRecord r,
boolean andResume, boolean checkConfig) {
// Is this activity's application already running?
// 如果是從Launcher啟動的話，這個時候應用進程是還沒有被創建的，所以這個的app返回為null
ProcessRecord app = mService.getProcessRecordLocked(r.processName,
r.info.applicationInfo.uid, true);
r.task.stack.setLaunchTime(r);
if (app != null && app.thread != null) {
try {
if ((r.info.flags&ActivityInfo.FLAG_MULTIPROCESS) == 0
|| !"android".equals(r.info.packageName)) {
// Don't add this if it is a platform component that is marked
// to run in multiple processes, because this is actually
// part of the framework so doesn't make sense to track as a
// separate apk in the process.
app.addPackage(r.info.packageName, r.info.applicationInfo.versionCode,
mService.mProcessStats);
}
// 如果不是從Launcher啟動，原來該Activity所在的進程已經存在
realStartActivityLocked(r, app, andResume, checkConfig);
return;
} catch (RemoteException e) {
Slog.w(TAG, "Exception when starting activity "
+ r.intent.getComponent().flattenToShortString(), e);
}
// If a dead object exception was thrown -- fall through to
// restart the application.
}
// 創建一個新的進程用來運行Activity所在應用
mService.startProcessLocked(r.processName, r.info.applicationInfo, true, 0,
"activity", r.intent.getComponent(), false, false, true);
}
13 ActivityManagerService.startProcessLocked()
final ProcessRecord startProcessLocked(String processName,
ApplicationInfo info, boolean knownToBeDead, int intentFlags,
String hostingType, ComponentName hostingName, boolean allowWhileBooting,
boolean isolated, boolean keepIfLarge) {
return startProcessLocked(processName, info, knownToBeDead, intentFlags, hostingType,
hostingName, allowWhileBooting, isolated, 0 /* isolatedUid */, keepIfLarge,
null /* ABI override */, null /* entryPoint */, null /* entryPointArgs */,
null /* crashHandler */);
}
final ProcessRecord startProcessLocked(String processName, ApplicationInfo info,
boolean knownToBeDead/*true*/, int intentFlags/*0*/, String hostingType/*"activity"*/,
ComponentName hostingName/*r.intent.getComponent()*/,boolean allowWhileBooting/*false*/,
boolean isolated/*false*/, int isolatedUid/*0*/, boolean keepIfLarge/*true*/,String abiOverride/*null*/,
String entryPoint/*null*/, String[] entryPointArgs/*null*/, Runnable crashHandler/*null*/) {
long startTime = SystemClock.elapsedRealtime();
ProcessRecord app;
if (!isolated) {
// 查看是否已經有該Activity運行的進程信息
app = getProcessRecordLocked(processName, info.uid, keepIfLarge);
checkTime(startTime, "startProcess: after getProcessRecord");
if ((intentFlags & Intent.FLAG_FROM_BACKGROUND) != 0) {
// 不是通過UI交互啟動Activity，由后臺啟動
// 對于bad process(在較短時間內發生兩次crash的進程)，直接返回，表示啟動失敗
// If we are in the background, then check to see if this process
// is bad. If so, we will just silently fail.
if (mBadProcesses.get(info.processName, info.uid) != null) {
if (DEBUG_PROCESSES) Slog.v(TAG, "Bad process: " + info.uid
+ "/" + info.processName);
return null;
}
} else {
// 由UI交互來啟動Activity
// When the user is explicitly starting a process, then clear its
// crash count so that we won't make it bad until they see at
// least one crash dialog again, and make the process good again
// if it had been bad.
if (DEBUG_PROCESSES) Slog.v(TAG, "Clearing bad process: " + info.uid
+ "/" + info.processName);
mProcessCrashTimes.remove(info.processName, info.uid);
if (mBadProcesses.get(info.processName, info.uid) != null) {
EventLog.writeEvent(EventLogTags.AM_PROC_GOOD,
UserHandle.getUserId(info.uid), info.uid,
info.processName);
mBadProcesses.remove(info.processName, info.uid);
if (app != null) {
app.bad = false;
}
}
}
} else {
// If this is an isolated process, it can't re-use an existing process.
app = null;
}
// app launch boost for big.little configurations
// use cpusets to migrate freshly launched tasks to big cores
synchronized(ActivityManagerService.this) {
nativeMigrateToBoost();
mIsBoosted = true;
mBoostStartTime = SystemClock.uptimeMillis();
Message msg = mHandler.obtainMessage(APP_BOOST_DEACTIVATE_MSG);
mHandler.sendMessageDelayed(msg, APP_BOOST_MESSAGE_DELAY);
}
// We don't have to do anything more if:
// (1) There is an existing application record; and
// (2) The caller doesn't think it is dead, OR there is no thread
// object attached to it so we know it couldn't have crashed; and
// (3) There is a pid assigned to it, so it is either starting or
// already running.
if (DEBUG_PROCESSES) Slog.v(TAG_PROCESSES, "startProcess: name=" + processName
+ " app=" + app + " knownToBeDead=" + knownToBeDead
+ " thread=" + (app != null ? app.thread : null)
+ " pid=" + (app != null ? app.pid : -1));
if (app != null && app.pid > 0) {
if (!knownToBeDead || app.thread == null) {
// We already have the app running, or are waiting for it to
// come up (we have a pid but not yet its thread), so keep it.
if (DEBUG_PROCESSES) Slog.v(TAG_PROCESSES, "App already running: " + app);
// If this is a new package in the process, add the package to the list
app.addPackage(info.packageName, info.versionCode, mProcessStats);
checkTime(startTime, "startProcess: done, added package to proc");
return app;
}
// An application record is attached to a previous process,
// clean it up now.
if (DEBUG_PROCESSES || DEBUG_CLEANUP) Slog.v(TAG_PROCESSES, "App died: " + app);
checkTime(startTime, "startProcess: bad proc running, killing");
killProcessGroup(app.info.uid, app.pid);
handleAppDiedLocked(app, true, true);
checkTime(startTime, "startProcess: done killing old proc");
}
String hostingNameStr = hostingName != null
? hostingName.flattenToShortString() : null;
if (app == null) {
checkTime(startTime, "startProcess: creating new process record");
// 創建一個新的記錄進程信息對象
app = newProcessRecordLocked(info, processName, isolated, isolatedUid);
if (app == null) {
Slog.w(TAG, "Failed making new process record for "
+ processName + "/" + info.uid + " isolated=" + isolated);
return null;
}
app.crashHandler = crashHandler;
checkTime(startTime, "startProcess: done creating new process record");
} else {
// If this is a new package in the process, add the package to the list
app.addPackage(info.packageName, info.versionCode, mProcessStats);
checkTime(startTime, "startProcess: added package to existing proc");
}
// If the system is not ready yet, then hold off on starting this
// process until it is.
// 這個在systemReady()中有進行設置
if (!mProcessesReady
&& !isAllowedWhileBooting(info)
&& !allowWhileBooting) {
if (!mProcessesOnHold.contains(app)) {
mProcessesOnHold.add(app);
}
if (DEBUG_PROCESSES) Slog.v(TAG_PROCESSES,
"System not ready, putting on hold: " + app);
checkTime(startTime, "startProcess: returning with proc on hold");
return app;
}
checkTime(startTime, "startProcess: stepping in to startProcess");
startProcessLocked(
app, hostingType/*activity*/, hostingNameStr/*packagename+classname*/,
abiOverride/*null*/, entryPoint/*null*/, entryPointArgs/*null*/);
checkTime(startTime, "startProcess: done starting proc!");
return (app.pid != 0) ? app : null;
}
主要工作是對bad process進行移除，如果目標Activity所在的進程不存在，則通過newProcessRecordLocked方法來新建一個ProcessRecord,用于記錄進程運行的進程信息。調用該函數的重載函數。
private final void startProcessLocked(ProcessRecord app, String hostingType/*activity*/,
String hostingNameStr/*packagename+classname*/, String abiOverride, String entryPoint, String[] entryPointArgs) {
long startTime = SystemClock.elapsedRealtime();
// 如果是Launcher啟動的Activity，其進程還未創建，因而app.pid=0
if (app.pid > 0 && app.pid != MY_PID) {
// 非系統進程 MY_PID對應的是framework-res.apk運行的進程
checkTime(startTime, "startProcess: removing from pids map");
synchronized (mPidsSelfLocked) {
// mPidsSelfLocked保存的是當前正在運行的所有進程，按照pid排序
mPidsSelfLocked.remove(app.pid);
mHandler.removeMessages(PROC_START_TIMEOUT_MSG, app);
}
checkTime(startTime, "startProcess: done removing from pids map");
app.setPid(0);
}
if (DEBUG_PROCESSES && mProcessesOnHold.contains(app)) Slog.v(TAG_PROCESSES,
"startProcessLocked removing on hold: " + app);
// 保存的也是進程，在systemReady之后要進行啟動
mProcessesOnHold.remove(app);
// gid uid cpu......
app.gids = gids;
app.requiredAbi = requiredAbi;
app.instructionSet = instructionSet;
// Start the process. It will either succeed and return a result containing
// the PID of the new process, or else throw a RuntimeException.
boolean isActivityProcess = (entryPoint == null);
if (entryPoint == null) entryPoint = "android.app.ActivityThread";
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "Start proc: " +
app.processName);
checkTime(startTime, "startProcess: asking zygote to start proc");
// 由zygote fork一個子進程，用來運行當前Activity
Process.ProcessStartResult startResult = Process.start(entryPoint,
app.processName, uid, uid, gids, debugFlags, mountExternal,
app.info.targetSdkVersion, app.info.seinfo, requiredAbi, instructionSet,
app.info.dataDir, entryPointArgs);
checkTime(startTime, "startProcess: returned from zygote!");
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
if (app.isolated) {
mBatteryStatsService.addIsolatedUid(app.uid, app.info.uid);
}
mBatteryStatsService.noteProcessStart(app.processName, app.info.uid);
checkTime(startTime, "startProcess: done updating battery stats");
EventLog.writeEvent(EventLogTags.AM_PROC_START,
UserHandle.getUserId(uid), startResult.pid, uid,
app.processName, hostingType,
hostingNameStr != null ? hostingNameStr : "");
if (app.persistent) {
Watchdog.getInstance().processStarted(app.processName, startResult.pid);
}
checkTime(startTime, "startProcess: building log message");
StringBuilder buf = mStringBuilder;
buf.setLength(0);
buf.append("Start proc ");
buf.append(startResult.pid);
buf.append(':');
buf.append(app.processName);
buf.append('/');
UserHandle.formatUid(buf, uid);
if (!isActivityProcess) {
buf.append(" [");
buf.append(entryPoint);
buf.append("]");
}
buf.append(" for ");
buf.append(hostingType);
if (hostingNameStr != null) {
buf.append(" ");
buf.append(hostingNameStr);
}
Slog.i(TAG, buf.toString());
app.setPid(startResult.pid);
app.usingWrapper = startResult.usingWrapper;
app.removed = false;
app.killed = false;
app.killedByAm = false;
checkTime(startTime, "startProcess: starting to update pids map");
synchronized (mPidsSelfLocked) {
this.mPidsSelfLocked.put(startResult.pid, app);
if (isActivityProcess) {
// 發送超時消息
Message msg = mHandler.obtainMessage(PROC_START_TIMEOUT_MSG);
msg.obj = app;
mHandler.sendMessageDelayed(msg, startResult.usingWrapper
? PROC_START_TIMEOUT_WITH_WRAPPER : PROC_START_TIMEOUT);
}
}
checkTime(startTime, "startProcess: done updating pids map");
} catch (RuntimeException e) {
// XXX do better error recovery.
app.setPid(0);
mBatteryStatsService.noteProcessFinish(app.processName, app.info.uid);
if (app.isolated) {
mBatteryStatsService.removeIsolatedUid(app.uid, app.info.uid);
}
Slog.e(TAG, "Failure starting process " + app.processName, e);
}
}
在由Process.start()創建子進程時，指定了該進程的入口為ActivityThread.main().
14 ActivityThread.main()
public static void main(String[] args) {
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "ActivityThreadMain");
SamplingProfilerIntegration.start();
// CloseGuard defaults to true and can be quite spammy. We
// disable it here, but selectively enable it later (via
// StrictMode) on debug builds, but using DropBox, not logs.
CloseGuard.setEnabled(false);
Environment.initForCurrentUser();
// Set the reporter for event logging in libcore
EventLogger.setReporter(new EventLoggingReporter());
// Make sure TrustedCertificateStore looks in the right place for CA certificates
final File configDir = Environment.getUserConfigDirectory(UserHandle.myUserId());
TrustedCertificateStore.setDefaultUserDirectory(configDir);
Process.setArgV0("<pre-initialized>");
// 在android中，對于要使用Handler的線程，都需要有一個Looper對象
Looper.prepareMainLooper();
ActivityThread thread = new ActivityThread();
thread.attach(false);// 對于非系統進程，這里為false
if (sMainThreadHandler == null) {
sMainThreadHandler = thread.getHandler();
}
if (false) {
Looper.myLooper().setMessageLogging(new
LogPrinter(Log.DEBUG, "ActivityThread"));
}
// End of event ActivityThreadMain.
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
Looper.loop();
throw new RuntimeException("Main thread loop unexpectedly exited");
}
attach()
private void attach(boolean system) {
sCurrentActivityThread = this;
mSystemThread = system;
if (!system) {// 非系統應用
ViewRootImpl.addFirstDrawHandler(new Runnable() {
@Override
public void run() {
ensureJitEnabled();
}
});
// DDMS中顯示的進程名字
android.ddm.DdmHandleAppName.setAppName("<pre-initialized>",
UserHandle.myUserId());
RuntimeInit.setApplicationObject(mAppThread.asBinder());
// 得到IActivityManager
// 對于應用進程來說，因為是跨進程通信，這里其實是ActivityManagerProxy
// 而對于系統進程來說，因為是在同一個進程當中，所以得到的是ActivityManagerService
final IActivityManager mgr = ActivityManagerNative.getDefault();
try {
// ActivityManagerService.attachApplication()
mgr.attachApplication(mAppThread);
} catch (RemoteException ex) {
// Ignore
}
// Watch for getting close to heap limit.
// DC回收機制:當應用消耗的內存大于總內存的75%的時候，就要開始進行資源的回收了
BinderInternal.addGcWatcher(new Runnable() {
@Override public void run() {
if (!mSomeActivitiesChanged) {
return;
}
Runtime runtime = Runtime.getRuntime();
long dalvikMax = runtime.maxMemory();
long dalvikUsed = runtime.totalMemory() - runtime.freeMemory();
if (dalvikUsed > ((3*dalvikMax)/4)) {
if (DEBUG_MEMORY_TRIM) Slog.d(TAG, "Dalvik max=" + (dalvikMax/1024)
+ " total=" + (runtime.totalMemory()/1024)
+ " used=" + (dalvikUsed/1024));
mSomeActivitiesChanged = false;
try {
mgr.releaseSomeActivities(mAppThread);
} catch (RemoteException e) {
}
}
}
});
} else {//系統應用
//......
}
}
15 ActivityManagerService.attachApplication()
@Override
public final void attachApplication(IApplicationThread thread) {
synchronized (this) {
// 取得調用者的pid
int callingPid = Binder.getCallingPid();
final long origId = Binder.clearCallingIdentity();
attachApplicationLocked(thread, callingPid);
Binder.restoreCallingIdentity(origId);
}
}
attachApplicationLocked()主要工作是填充Activity所在進程信息到ProcessRecord對象，調用IApplicationThread.bindApplication()使得IApplicationThread關聯到進程信息，調用ActivityStackSupervisor.attachApplicationLocked()來啟動進程。
16 ActivityThread.ApplicationThread.bindApplication()
1)數據填充到AppBindData對象，然后發送BIND_APPLICATION消息給handler處理
2)調用handleBindApplication(data)繼續處理：DDMS顯示的進程名，對于長久運行的應用要關閉硬件加速，Context初始化，Instrumentation初始化，ContentProvider安裝，調用Instrumentation.onCreate()，Application.onCreate().
private void handleBindApplication(AppBindData data) {
if (data.trackAllocation) {
DdmVmInternal.enableRecentAllocations(true);
}
mBoundApplication = data;
mConfiguration = new Configuration(data.config);
mCompatConfiguration = new Configuration(data.config);
mProfiler = new Profiler();
if (data.initProfilerInfo != null) {
mProfiler.profileFile = data.initProfilerInfo.profileFile;
mProfiler.profileFd = data.initProfilerInfo.profileFd;
mProfiler.samplingInterval = data.initProfilerInfo.samplingInterval;
mProfiler.autoStopProfiler = data.initProfilerInfo.autoStopProfiler;
}
// send up app name; do this *before* waiting for debugger
Process.setArgV0(data.processName);
// 設置DDMS中顯示的進程名
android.ddm.DdmHandleAppName.setAppName(data.processName,
UserHandle.myUserId());
if (data.persistent) {
// 對于一直要運行在后臺的進程，在低內存設備要關閉硬件加速功能
// Persistent processes on low-memory devices do not get to
// use hardware accelerated drawing, since this can add too much
// overhead to the process.
if (!ActivityManager.isHighEndGfx()) {
HardwareRenderer.disable(false);
}
}
if (mProfiler.profileFd != null) {
mProfiler.startProfiling();
}
// If the app is Honeycomb MR1 or earlier, switch its AsyncTask
// implementation to use the pool executor. Normally, we use the
// serialized executor as the default. This has to happen in the
// main thread so the main looper is set right.
if (data.appInfo.targetSdkVersion <= android.os.Build.VERSION_CODES.HONEYCOMB_MR1) {
AsyncTask.setDefaultExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
}
Message.updateCheckRecycle(data.appInfo.targetSdkVersion);
/*
* Before spawning a new process, reset the time zone to be the system time zone.
* This needs to be done because the system time zone could have changed after the
* the spawning of this process. Without doing this this process would have the incorrect
* system time zone.
*/
TimeZone.setDefault(null);
/*
* Initialize the default locale in this process for the reasons we set the time zone.
*/
Locale.setDefault(data.config.locale);
/*
* Update the system configuration since its preloaded and might not
* reflect configuration changes. The configuration object passed
* in AppBindData can be safely assumed to be up to date
*/
mResourcesManager.applyConfigurationToResourcesLocked(data.config, data.compatInfo);
mCurDefaultDisplayDpi = data.config.densityDpi;
applyCompatConfiguration(mCurDefaultDisplayDpi);
// LoadedApk對象
data.info = getPackageInfoNoCheck(data.appInfo, data.compatInfo);
/**
* Switch this process to density compatibility mode if needed.
*/
if ((data.appInfo.flags&ApplicationInfo.FLAG_SUPPORTS_SCREEN_DENSITIES)
== 0) {
mDensityCompatMode = true;
Bitmap.setDefaultDensity(DisplayMetrics.DENSITY_DEFAULT);
}
updateDefaultDensity();
// Context初始化(ContextImpl)
final ContextImpl appContext = ContextImpl.createAppContext(this, data.info);
if (!Process.isIsolated()) {
final File cacheDir = appContext.getCacheDir();
if (cacheDir != null) {
// Provide a usable directory for temporary files
System.setProperty("java.io.tmpdir", cacheDir.getAbsolutePath());
} else {
Log.v(TAG, "Unable to initialize \"java.io.tmpdir\" property due to missing cache directory");
}
// Use codeCacheDir to store generated/compiled graphics code and jit profiling data.
final File codeCacheDir = appContext.getCodeCacheDir();
if (codeCacheDir != null) {
setupGraphicsSupport(data.info, codeCacheDir);
setupJitProfileSupport(data.info, codeCacheDir);
} else {
Log.e(TAG, "Unable to setupGraphicsSupport and setupJitProfileSupport " +
"due to missing code-cache directory");
}
}
final boolean is24Hr = "24".equals(mCoreSettings.getString(Settings.System.TIME_12_24));
DateFormat.set24HourTimePref(is24Hr);
View.mDebugViewAttributes =
mCoreSettings.getInt(Settings.Global.DEBUG_VIEW_ATTRIBUTES, 0) != 0;
/**
* For system applications on userdebug/eng builds, log stack
* traces of disk and network access to dropbox for analysis.
*/
if ((data.appInfo.flags &
(ApplicationInfo.FLAG_SYSTEM |
ApplicationInfo.FLAG_UPDATED_SYSTEM_APP)) != 0) {
StrictMode.conditionallyEnableDebugLogging();
}
/**
* For apps targetting SDK Honeycomb or later, we don't allow
* network usage on the main event loop / UI thread.
*
* Note to those grepping: this is what ultimately throws
* NetworkOnMainThreadException ...
*/
if (data.appInfo.targetSdkVersion > 9) {
StrictMode.enableDeathOnNetwork();
}
NetworkSecurityPolicy.getInstance().setCleartextTrafficPermitted(
(data.appInfo.flags & ApplicationInfo.FLAG_USES_CLEARTEXT_TRAFFIC) != 0);
if (data.debugMode != IApplicationThread.DEBUG_OFF) {// DEBUG
// XXX should have option to change the port.
Debug.changeDebugPort(8100);
if (data.debugMode == IApplicationThread.DEBUG_WAIT) {
Slog.w(TAG, "Application " + data.info.getPackageName()
+ " is waiting for the debugger on port 8100...");
IActivityManager mgr = ActivityManagerNative.getDefault();
try {
mgr.showWaitingForDebugger(mAppThread, true);
} catch (RemoteException ex) {
}
Debug.waitForDebugger();
try {
mgr.showWaitingForDebugger(mAppThread, false);
} catch (RemoteException ex) {
}
} else {
Slog.w(TAG, "Application " + data.info.getPackageName()
+ " can be debugged on port 8100...");
}
}
// Enable OpenGL tracing if required
if (data.enableOpenGlTrace) {
GLUtils.setTracingLevel(1);
}
// Allow application-generated systrace messages if we're debuggable.
boolean appTracingAllowed = (data.appInfo.flags&ApplicationInfo.FLAG_DEBUGGABLE) != 0;
Trace.setAppTracingAllowed(appTracingAllowed);
/**
* Initialize the default http proxy in this process for the reasons we set the time zone.
*/
IBinder b = ServiceManager.getService(Context.CONNECTIVITY_SERVICE);
if (b != null) {
// In pre-boot mode (doing initial launch to collect password), not
// all system is up. This includes the connectivity service, so don't
// crash if we can't get it.
IConnectivityManager service = IConnectivityManager.Stub.asInterface(b);
try {
final ProxyInfo proxyInfo = service.getProxyForNetwork(null);
Proxy.setHttpProxySystemProperty(proxyInfo);
} catch (RemoteException e) {}
}
if (data.instrumentationName != null) {
InstrumentationInfo ii = null;
try {
ii = appContext.getPackageManager().
getInstrumentationInfo(data.instrumentationName, 0);
} catch (PackageManager.NameNotFoundException e) {
}
if (ii == null) {
throw new RuntimeException(
"Unable to find instrumentation info for: "
+ data.instrumentationName);
}
mInstrumentationPackageName = ii.packageName;
mInstrumentationAppDir = ii.sourceDir;
mInstrumentationSplitAppDirs = ii.splitSourceDirs;
mInstrumentationLibDir = ii.nativeLibraryDir;
mInstrumentedAppDir = data.info.getAppDir();
mInstrumentedSplitAppDirs = data.info.getSplitAppDirs();
mInstrumentedLibDir = data.info.getLibDir();
ApplicationInfo instrApp = new ApplicationInfo();
instrApp.packageName = ii.packageName;
instrApp.sourceDir = ii.sourceDir;
instrApp.publicSourceDir = ii.publicSourceDir;
instrApp.splitSourceDirs = ii.splitSourceDirs;
instrApp.splitPublicSourceDirs = ii.splitPublicSourceDirs;
instrApp.dataDir = ii.dataDir;
instrApp.nativeLibraryDir = ii.nativeLibraryDir;
LoadedApk pi = getPackageInfo(instrApp, data.compatInfo,
appContext.getClassLoader(), false, true, false);
ContextImpl instrContext = ContextImpl.createAppContext(this, pi);
try {
java.lang.ClassLoader cl = instrContext.getClassLoader();
mInstrumentation = (Instrumentation)
cl.loadClass(data.instrumentationName.getClassName()).newInstance();
} catch (Exception e) {
throw new RuntimeException(
"Unable to instantiate instrumentation "
+ data.instrumentationName + ": " + e.toString(), e);
}
mInstrumentation.init(this, instrContext, appContext,
new ComponentName(ii.packageName, ii.name), data.instrumentationWatcher,
data.instrumentationUiAutomationConnection);
if (mProfiler.profileFile != null && !ii.handleProfiling
&& mProfiler.profileFd == null) {
mProfiler.handlingProfiling = true;
File file = new File(mProfiler.profileFile);
file.getParentFile().mkdirs();
Debug.startMethodTracing(file.toString(), 8 * 1024 * 1024);
}
} else {
// 創建Instrumentation
mInstrumentation = new Instrumentation();
}
if ((data.appInfo.flags&ApplicationInfo.FLAG_LARGE_HEAP) != 0) {
// 申請了大內存
dalvik.system.VMRuntime.getRuntime().clearGrowthLimit();
} else {
// Small heap, clamp to the current growth limit and let the heap release
// pages after the growth limit to the non growth limit capacity. b/18387825
dalvik.system.VMRuntime.getRuntime().clampGrowthLimit();
}
// Allow disk access during application and provider setup. This could
// block processing ordered broadcasts, but later processing would
// probably end up doing the same disk access.
final StrictMode.ThreadPolicy savedPolicy = StrictMode.allowThreadDiskWrites();
try {
// If the app is being launched for full backup or restore, bring it up in
// a restricted environment with the base application class.
// 創建Application
Application app = data.info.makeApplication(data.restrictedBackupMode, null);
mInitialApplication = app;
// don't bring up providers in restricted mode; they may depend on the
// app's custom Application class
if (!data.restrictedBackupMode) {
// ContentProvider安裝
List<ProviderInfo> providers = data.providers;
if (providers != null) {
installContentProviders(app, providers);
// For process that contains content providers, we want to
// ensure that the JIT is enabled "at some point".
mH.sendEmptyMessageDelayed(H.ENABLE_JIT, 10*1000);
}
}
// Do this after providers, since instrumentation tests generally start their
// test thread at this point, and we don't want that racing.
try {
// Instrumentation.onCreate()運行在Contentprovider安裝之后
mInstrumentation.onCreate(data.instrumentationArgs);
}
catch (Exception e) {
throw new RuntimeException(
"Exception thrown in onCreate() of "
+ data.instrumentationName + ": " + e.toString(), e);
}
try {
// Application.onCreate()
mInstrumentation.callApplicationOnCreate(app);
} catch (Exception e) {
if (!mInstrumentation.onException(app, e)) {
throw new RuntimeException(
"Unable to create application " + app.getClass().getName()
+ ": " + e.toString(), e);
}
}
} finally {
StrictMode.setThreadPolicy(savedPolicy);
}
}
17 ActivityStackSupervisor.attachApplicationLocked()
boolean attachApplicationLocked(ProcessRecord app) throws RemoteException {
final String processName = app.processName;
boolean didSomething = false;
// mActivityDisplays保存的是所有進程中運行的ActivityTask
for (int displayNdx = mActivityDisplays.size() - 1; displayNdx >= 0; --displayNdx) {
ArrayList<ActivityStack> stacks = mActivityDisplays.valueAt(displayNdx).mStacks;
for (int stackNdx = stacks.size() - 1; stackNdx >= 0; --stackNdx) {
final ActivityStack stack = stacks.get(stackNdx);
if (!isFrontStack(stack)) {
continue;
}
// 對于沒有啟動的進程，hr.app是為null的
ActivityRecord hr = stack.topRunningActivityLocked(null);
if (hr != null) {
if (hr.app == null && app.uid == hr.info.applicationInfo.uid
&& processName.equals(hr.processName)) {
try {// 找到了進程中的Activity，啟動它
if (realStartActivityLocked(hr, app, true, true)) {
didSomething = true;
}
} catch (RemoteException e) {
Slog.w(TAG, "Exception in new application when starting activity "
+ hr.intent.getComponent().flattenToShortString(), e);
throw e;
}
}
}
}
}
if (!didSomething) {
ensureActivitiesVisibleLocked(null, 0);
}
return didSomething;
}
后續流程：ActivityThread.ApplicationThread.scheduleLaunchActivity-->發送 LAUNCH_ACTIVITY消息-->handleLaunchActivity(r, null)-->performLaunchActivity().
