android第三方服务进程启动,Android Phone进程启动过程

相关源码:

packages/services/Telephony

- src/com/android/phone/PhoneApp.java

- AndroidManifest.xml

frameworks/base/services/core/java/com/android/server/

- am/ActivityManagerService.java

frameworks/base/services/java/com/android/server/

- SystemServer.java

frameworks/base/core/java/android/os/

- Process.java

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在packages/services/Telephony/AndroidManifest.xml中，PhoneApp的属性android:persistent="true"，ActivityManagerService在启动后会去遍历所有android:persistent="true"的应用，而后交由Process通过socket通知zygote fork一个新的进程，phone进程启动具体过程如下：

1 注册ActivityManagerService

SystemServer执行main方法，接着执行run,在run中有这样一段

frameworks/base/services/java/com/android/server/SystemServer.java

private void run() {

startBootstrapServices();

startCoreServices();

startOtherServices();

}

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其中的startBootstrapServices方法去调用startService启动ActivityManagerService。

frameworks/base/services/java/com/android/server/SystemServer.java

private void startBootstrapServices() {

// Activity manager runs the show.

mActivityManagerService = mSystemServiceManager.startService(

ActivityManagerService.Lifecycle.class).getService();

...

// Set up the Application instance for the system process and get started.

mActivityManagerService.setSystemProcess();

}

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startService会回调Lifecycle.onStart()，这时已经创建好ActivityManagerService对象mActivityManagerService，然后在SystemServer的startBootstrapServices中继续调用ActivityManagerService的setSystemProcess，

在ServiceManager中完成注册ActivityManagerService。

frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java

public void setSystemProcess() {

ServiceManager.addService(Context.ACTIVITY_SERVICE, this, true);

}

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至此ActivityManagerService完成了初始化。

2 遍历persistent进程

SystemServer执行startBootstrapServices完成AMS的初始化后，继续调用startOtherServices。

frameworks/base/services/java/com/android/server/SystemServer.java

private void startOtherServices() {

mActivityManagerService.systemReady(new Runnable() ...

}

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在ActivityManagerService.systemReady中遍历所有persistent进程。

frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java

public void systemReady(final Runnable goingCallback) {

...

synchronized (this) {

if (mFactoryTest != FactoryTest.FACTORY_TEST_LOW_LEVEL) {

try {//遍历所有android:persistent属性为true的进程,PhoneApp的persistent也为true

List apps = AppGlobals.getPackageManager().

getPersistentApplications(STOCK_PM_FLAGS);

if (apps != null) {

int N = apps.size();

int i;

for (i=0; i

ApplicationInfo info

= (ApplicationInfo)apps.get(i);

if (info != null &&

!info.packageName.equals("android")) {

addAppLocked(info, false, null /* ABI override */);//persistent进程启动，Phone进程也不例外

}

}

}

} catch (RemoteException ex) {

// pm is in same process, this will never happen.

}

}

// Start up initial activity.

mBooting = true;

startHomeActivityLocked(mCurrentUserId, "systemReady");//启动launcher

...

}

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接着进入addAppLocked，启动persistent进程

frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java

final ProcessRecord addAppLocked(ApplicationInfo info, boolean isolated,

String abiOverride) {

startProcessLocked(app, "added application", app.processName, abiOverride,

null /* entryPoint */, null /* entryPointArgs */);

}

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需要继续调用startProcessLocked，尤其注意if (entryPoint == null) entryPoint = "android.app.ActivityThread";,entryPoint将作为zygote fork phone进程的参数。

frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java

private final void startProcessLocked(ProcessRecord app, String hostingType,

String hostingNameStr, String abiOverride, String entryPoint, String[] entryPointArgs) {

...

// 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";//记住这个类名，zygote会反射调用其main()方法

Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "Start proc: " +

app.processName);

checkTime(startTime, "startProcess: asking zygote to start proc");

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);

...

}

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3 fork phone进程

Process.start继续调用startViaZygote，startViaZygote继续调zygoteSendArgsAndGetResult，通过LocalSocket，带上类名等参数，if (entryPoint == null) entryPoint = "android.app.ActivityThread",通知Zygote fork phone进程，Zygote通过native方法 fork phone进程后，会反射进入ActivityThread的main方法，main继续调用Application的onCreate。

frameworks/base/core/java/android/os/Process.java

private static ProcessStartResult zygoteSendArgsAndGetResult(ZygoteState zygoteState, ArrayList args){

int sz = args.size();

for (int i = 0; i < sz; i++) {

String arg = args.get(i);

if (arg.indexOf('\n') >= 0) {

throw new ZygoteStartFailedEx(

"embedded newlines not allowed");

}

writer.write(arg);

writer.newLine();

}

writer.flush();

}

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4 PhoneApp 入口

PhoneApp继承了Application，进程fork后，ActivityThread会去调用其onCreate方法,之后就可以进入电话、数据连接、短彩信流程了。

总结

在ActivityManagerService启动之后，AMS会遍历所有persistent为true的应用，通过过LocalSocket通知Zygote fork phone进程，接着反射执行ActivityThread的main方法，ActivityThread会去调用PhoneApp的onCreate方法。