1、Activity的启动方式
在android中，启动activity的方式有很多种，比如通过launcher来启动，比如通过调用activity的startActivity()方法来启动，adb shell 命令来启动等等，这里只简单过一下点击桌面启动Activity的流程。
2、Launcher.java中启动activity
launcher是activity的一个子类，关于launcher原码分析这里暂时不考虑，从点击shortcut开始来分析。
/**
* 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) {// 应用的第一个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是否为null，最终都是调用mInstrumentation.execStartActivity 来启动另外Activity的。
public ActivityResult execStartActivity(
Context who, IBinder contextThread/**/, IBinder token/**/, Activity target,
Intent intent, int requestCode, Bundle options) {
// 调用者是哪一个
IApplicationThread whoThread = (IApplicationThread) contextThread;
Uri referrer = target != null ? target.onProvideReferrer() : null;
if (referrer != null) {
intent.putExtra(Intent.EXTRA_REFERRER, referrer);
}
if (mActivityMonitors != null) {// 对启动的activity进行检查
synchronized (mSync) {
final int N = mActivityMonitors.size();
for (int i=0; i= 0 ? am.getResult() : null;
}
break;
}
}
}
}
try {
intent.migrateExtraStreamToClipData();
intent.prepareToLeaveProcess();
// 调用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端的流程到这里就已经结束了，后续就跳转到Server端了，在分析Server端之前，先理一下几个类的关系：
ActivityRecord：Activity相关的信息都保存在这个对象中；
ActivityStask:这是一个独立的栈，用来保存和管理ActivityRecord；
ActivityStackSupervisor：用来调度管理ActivityStask
QQ截图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) {
// 是否有权限启动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.
// 从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) {
// 调用者的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;
}
// 一个activity栈，用来管理里面的activities，因为activity由activityrecord来存储，所以ActivityStack 管理的其实是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) {
// 记录一个Activity(这个activity是Android中的四大组件，而非PMS解析APK得到的那个activity)的所有信息,由ActivityStack进行管理
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()
该函数主要工作是检查调用者Launcher权限，调用者是否需要返回结果，检查目标Intent是否正确，检查目标activity是否存在，检查是否具有调用startActivity权限；检查通过后创建目标activity对应的activityrecord，然后交给startActivityUncheckedLocked继续处理。
8 ActivityStackSupervisor.startActivityUncheckedLocked()
该方法主要工作：
1）根据目标Activity的LaunchMode决定是否需要建立新的Task
2）检查是否有可重用的Task和Activity
3）查找是否具有可重用的Activity（ActivityRecord）
4）TaskRecord和Activity关联起来
5）工作继续交由ActivityStack.startActivityLocked()来完成。
9 ActivityStack.startActivityLocked()
该方法的主要工作是：根据要启动的Activity所在的Task是否存在来决定是从原有的Task队列中找还是新建一个task，然后更改该task在任务队列的位置，准备Activity启动动画，然后将工作交给ActivityStackSupervisor.resumeTopActivitiesLocked();
10 ActivityStackSupervisor.resumeTopActivitiesLocked()
判断栈顶是否有需要显示的Activity，暂停所有处于栈顶的Activity（调用ActivityStack.resumeTopActivityLocked()方法）
11 ActivityStack.resumeTopActivityInnerLocked()
调用ActivityStackSupervisor.pauseBackStacks()暂停所有的Activity，调用ActivityStackSupervisor.startSpecificActivityLocked(next, true, true)来启动目标Activity。
12 ActivityStackSupervisor.startSpecificActivityLocked()
void startSpecificActivityLocked(ActivityRecord r,
boolean andResume, boolean checkConfig) {
// Is this activity's application already running?
// 如果是从Launcher启动的话，这个时候应用进程是还没有被创建的，所以这个的app返回为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);
}
// 如果不是从Launcher启动，原来该Activity所在的进程已经存在
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.
}
// 创建一个新的进程用来运行Activity所在应用
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) {
// 查看是否已经有该Activity运行的进程信息
app = getProcessRecordLocked(processName, info.uid, keepIfLarge);
checkTime(startTime, "startProcess: after getProcessRecord");
if ((intentFlags & Intent.FLAG_FROM_BACKGROUND) != 0) {
// 不是通过UI交互启动Activity，由后台启动
// 对于bad process(在较短时间内发生两次crash的进程)，直接返回，表示启动失败
// 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交互来启动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");
// 创建一个新的记录进程信息对象
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.
// 这个在systemReady()中有进行设置
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;
}
主要工作是对bad process进行移除，如果目标Activity所在的进程不存在，则通过newProcessRecordLocked方法来新建一个ProcessRecord,用于记录进程运行的进程信息。调用该函数的重载函数。
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启动的Activity，其进程还未创建，因而app.pid=0
if (app.pid > 0 && app.pid != MY_PID) {
// 非系统进程 MY_PID对应的是framework-res.apk运行的进程
checkTime(startTime, "startProcess: removing from pids map");
synchronized (mPidsSelfLocked) {
// mPidsSelfLocked保存的是当前正在运行的所有进程，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);
// 保存的也是进程，在systemReady之后要进行启动
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一个子进程，用来运行当前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) {
// 发送超时消息
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()创建子进程时，指定了该进程的入口为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("");
// 在android中，对于要使用Handler的线程，都需要有一个Looper对象
Looper.prepareMainLooper();
ActivityThread thread = new ActivityThread();
thread.attach(false);// 对于非系统进程，这里为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) {// 非系统应用
ViewRootImpl.addFirstDrawHandler(new Runnable() {
@Override
public void run() {
ensureJitEnabled();
}
});
// DDMS中显示的进程名字
android.ddm.DdmHandleAppName.setAppName("",
UserHandle.myUserId());
RuntimeInit.setApplicationObject(mAppThread.asBinder());
// 得到IActivityManager
// 对于应用进程来说，因为是跨进程通信，这里其实是ActivityManagerProxy
// 而对于系统进程来说，因为是在同一个进程当中，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回收机制:当应用消耗的内存大于总内存的75%的时候，就要开始进行资源的回收了
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 {//系统应用
//......
}
}
15 ActivityManagerService.attachApplication()
@Override
public final void attachApplication(IApplicationThread thread) {
synchronized (this) {
// 取得调用者的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所在进程信息到ProcessRecord对象，调用IApplicationThread.bindApplication()使得IApplicationThread关联到进程信息，调用ActivityStackSupervisor.attachApplicationLocked()来启动进程。
16 ActivityThread.ApplicationThread.bindApplication()
1)数据填充到AppBindData对象，然后发送BIND_APPLICATION消息给handler处理
2)调用handleBindApplication(data)继续处理：DDMS显示的进程名，对于长久运行的应用要关闭硬件加速，Context初始化，Instrumentation初始化，ContentProvider安装，调用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);
// 设置DDMS中显示的进程名
android.ddm.DdmHandleAppName.setAppName(data.processName,
UserHandle.myUserId());
if (data.persistent) {
// 对于一直要运行在后台的进程，在低内存设备要关闭硬件加速功能
// 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对象
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 {
// 创建Instrumentation
mInstrumentation = new Instrumentation();
}
if ((data.appInfo.flags&ApplicationInfo.FLAG_LARGE_HEAP) != 0) {
// 申请了大内存
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.
// 创建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安装
List 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()运行在Contentprovider安装之后
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保存的是所有进程中运行的ActivityTask
for (int displayNdx = mActivityDisplays.size() - 1; displayNdx >= 0; --displayNdx) {
ArrayList stacks = mActivityDisplays.valueAt(displayNdx).mStacks;
for (int stackNdx = stacks.size() - 1; stackNdx >= 0; --stackNdx) {
final ActivityStack stack = stacks.get(stackNdx);
if (!isFrontStack(stack)) {
continue;
}
// 对于没有启动的进程，hr.app是为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 {// 找到了进程中的Activity，启动它
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;
}
后续流程：ActivityThread.ApplicationThread.scheduleLaunchActivity-->发送 LAUNCH_ACTIVITY消息-->handleLaunchActivity(r, null)-->performLaunchActivity().