ActivityThread启动源码解析

最新推荐文章于 2024-05-03 22:04:59 发布

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最新推荐文章于 2024-05-03 22:04:59 发布

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分类专栏： android

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本文详细解析了Android应用从启动到Activity生命周期的变化过程。通过跟踪ActivityThread类中的关键方法，如attach、bindApplication等，揭示了Application如何被创建以及LoadedApk的作用。深入探讨了IApplicationThread接口的应用，并解释了Handler在消息传递中的作用。

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https://github.com/android/platform_frameworks_base/blob/master/core/java/android/app/ActivityThread.java
1.启动，走attach
ActivityThread thread = new ActivityThread();
thread.attach(false);
2 获取一个代理，则进入AMS查看attachApplication
final IActivityManager mgr = ActivityManager.getService();
mgr.attachApplication(mAppThread);
3 thread.bindApplication 这里thread指的是ActivityThread种的IApplicationThread
4 ApplicationThread 继承IApplicationThread
进入ApplicationThread bindApplication
sendMessage(H.BIND_APPLICATION, data);
mH.sendMessage(msg);
5final H mH = new H();
所以找一下H这个类，就是Handler
这里启动Activity生命周期都是一个套路
ApplicationThread 调用 IApplicationThread定义的接口
这里是bindApplication.生命周期是schedulexxx
给H发msg
回调 ActivityThread handlerxxx
performxxx

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;
Application app = data.info.makeApplication(data.restrictedBackupMode, null);
mInitialApplication = app;
mInstrumentation.callApplicationOnCreate(app);

    data.info = getPackageInfoNoCheck(data.appInfo, data.compatInfo);

这里知道LoadedApk怎么创建的
Application怎么创建的
public final LoadedApk peekPackageInfo(String packageName, boolean includeCode) {
synchronized (mResourcesManager) {
WeakReference ref;
if (includeCode) {
ref = mPackages.get(packageName);
} else {
ref = mResourcePackages.get(packageName);
}
return ref != null ? ref.get() : null;
}
}

好的，总结一下，这里Application在LoadedApk创建，
LoadedApk存在Map类型的数据结构，以包名也就是一个进程对应一个

public Application makeApplication(boolean forceDefaultAppClass,
Instrumentation instrumentation) {
if (mApplication != null) {
return mApplication;
}

    Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "makeApplication");

    Application app = null;

    String appClass = mApplicationInfo.className;
    if (forceDefaultAppClass || (appClass == null)) {
        appClass = "android.app.Application";
    }

    try {
        java.lang.ClassLoader cl = getClassLoader();
        if (!mPackageName.equals("android")) {
            Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER,
                    "initializeJavaContextClassLoader");
            initializeJavaContextClassLoader();
            Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
        }
        ContextImpl appContext = ContextImpl.createAppContext(mActivityThread, this);
        app = mActivityThread.mInstrumentation.newApplication(
                cl, appClass, appContext);
        appContext.setOuterContext(app);
    } catch (Exception e) {
        if (!mActivityThread.mInstrumentation.onException(app, e)) {
            Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
            throw new RuntimeException(
                "Unable to instantiate application " + appClass
                + ": " + e.toString(), e);
        }
    }
    mActivityThread.mAllApplications.add(app);
    mApplication = app;

    if (instrumentation != null) {
        try {
            instrumentation.callApplicationOnCreate(app);
        } catch (Exception e) {
            if (!instrumentation.onException(app, e)) {
                Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
                throw new RuntimeException(
                    "Unable to create application " + app.getClass().getName()
                    + ": " + e.toString(), e);
            }
        }
    }

    // Rewrite the R 'constants' for all library apks.
    SparseArray<String> packageIdentifiers = getAssets().getAssignedPackageIdentifiers();
    final int N = packageIdentifiers.size();
    for (int i = 0; i < N; i++) {
        final int id = packageIdentifiers.keyAt(i);
        if (id == 0x01 || id == 0x7f) {
            continue;
        }

        rewriteRValues(getClassLoader(), packageIdentifiers.valueAt(i), id);
    }

    Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);

    return app;
}

Instrumentation

public Application newApplication(Class