Activity启动流程

贺祥 | 发表于 | 分类于

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Activity启动流程

  1. context.startActivity调用AMS系统服务，发起binder调用

  2. 是否需要创建进程，执行进程启动流程，同时挂起Activity或者service等相关组件，等待进程启动完成

    #进程启动流程
2.1 AMS像Zygote通过socket发送命令启动进程
2.2 Zygote收到命令会调用runeOnce方法，fork进程
2.3 zygote fork用进程后，会执行ActivityThread的Main函，这个ActivityThread类入口来自AMS发送的Socket参数
2.4 进程启动后会像AMS报告，attachApplication binder调用

  3. 进程启动好后AMS 通过binder调用应用的bindApplication，初始化应用

  4. 创建Acitivty 对象，准备好aplication，创建contextImpl，attach 上下文

  5. 生命周期回调 OnCreate

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    /**  Core implementation of activity launch. */
       private Activity performLaunchActivity(ActivityClientRecord r, Intent customIntent) {
           ContextImpl appContext = createBaseContextForActivity(r);
       
           try {
               java.lang.ClassLoader cl = appContext.getClassLoader();
               activity = mInstrumentation.newActivity(
                       cl, component.getClassName(), r.intent);
           } catch (Exception e) {
               if (!mInstrumentation.onException(activity, e)) {
                   throw new RuntimeException(
                       "Unable to instantiate activity " + component
                       + ": " + e.toString(), e);
               }
           }
       
           try {
               Application app = r.packageInfo.makeApplicationInner(false, mInstrumentation);
               if (activity != null) {
                   activity.attach(appContext, this, getInstrumentation(), r.token,
                           r.ident, app, r.intent, r.activityInfo, title, r.parent,
                           r.embeddedID, r.lastNonConfigurationInstances, config,
                           r.referrer, r.voiceInteractor, window, r.activityConfigCallback,
                           r.assistToken, r.shareableActivityToken);
                   if (theme != 0) {
                       activity.setTheme(theme);
                   }
                   if (r.isPersistable()) {
                       mInstrumentation.callActivityOnCreate(activity, r.state, r.persistentState);
                   } else {
                       mInstrumentation.callActivityOnCreate(activity, r.state);
                   }
               }
       
            } catch (SuperNotCalledException e) {
               throw e;
       
           } catch (Exception e) {
           }
       
           return activity;
       }

  6. 接着activity 显示原理