源码分析:Activity生命周期调用顺序(二)

Activity生命周期调用顺序,接着上篇
源码分析:Activity声明周期调用顺序(一)

当进入一个Activity后,会执行attach()→onCreate()→onStart()→onRestoreInstanceState()→onPostCreate()→onResume()→onPostResume()等方法

ActivityThread.H 的handleMessage()方法


 public void handleMessage(Message msg) {
			...
            switch (msg.what) {
				//启动Activity
                case LAUNCH_ACTIVITY: {
                   
                    final ActivityClientRecord r = (ActivityClientRecord) msg.obj;

                    r.packageInfo = getPackageInfoNoCheck(
                            r.activityInfo.applicationInfo, r.compatInfo);
					//【注:1】处理启动的Activity
                    handleLaunchActivity(r, null, "LAUNCH_ACTIVITY");
                } break;
			...

【注:1】 handleLaunchActivity()

//我们只看,要打开的activity的声明周期
private void handleLaunchActivity(ActivityClientRecord r, Intent customIntent, String reason) {
        ...

        // Make sure we are running with the most recent config.
        handleConfigurationChanged(null, null);

        
        WindowManagerGlobal.initialize();
		//【注:2】 这里执行了attach跟oncreate等
        Activity a = performLaunchActivity(r, customIntent);

        if (a != null) {
            r.createdConfig = new Configuration(mConfiguration);
            reportSizeConfigurations(r);
            Bundle oldState = r.state;
			//【注:3】 这里执行了onResume等
            handleResumeActivity(r.token, false, r.isForward,
                    !r.activity.mFinished && !r.startsNotResumed, r.lastProcessedSeq, reason);

            if (!r.activity.mFinished && r.startsNotResumed) {
               
                performPauseActivityIfNeeded(r, reason);

                
                if (r.isPreHoneycomb()) {
                    r.state = oldState;
                }
            }
        } else {
            
            try {
                ActivityManager.getService()
                    .finishActivity(r.token, Activity.RESULT_CANCELED, null,
                            Activity.DONT_FINISH_TASK_WITH_ACTIVITY);
            } catch (RemoteException ex) {
                throw ex.rethrowFromSystemServer();
            }
        }
    }

【注:2】 performLaunchActivity()

 private Activity performLaunchActivity(ActivityClientRecord r, Intent customIntent) {

        ...

        ContextImpl appContext = createBaseContextForActivity(r);
        Activity activity = null;
        
			
            java.lang.ClassLoader cl = appContext.getClassLoader();
			//创建Activity
            activity = mInstrumentation.newActivity(
                    cl, component.getClassName(), r.intent);
            
           

        try {
           

            if (activity != null) {
				...
                //执行activity的onAttach()方法
                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.configCallback);

                
                activity.mCalled = false;
				//执行activity的onCreate()方法
                if (r.isPersistable()) {
                    mInstrumentation.callActivityOnCreate(activity, r.state, r.persistentState);
                } else {
                    mInstrumentation.callActivityOnCreate(activity, r.state);
                }
                if (!activity.mCalled) {
                    throw new SuperNotCalledException(
                        "Activity " + r.intent.getComponent().toShortString() +
                        " did not call through to super.onCreate()");
                }
                r.activity = activity;
                r.stopped = true;
                if (!r.activity.mFinished) {
					//执行Activity的onStart()方法
                    activity.performStart();
                    r.stopped = false;
                }
				//执行Activity的onRestoreInstance()方法
                if (!r.activity.mFinished) {
                    if (r.isPersistable()) {
                        if (r.state != null || r.persistentState != null) {
                            mInstrumentation.callActivityOnRestoreInstanceState(activity, r.state,
                                    r.persistentState);
                        }
                    } else if (r.state != null) {
                        mInstrumentation.callActivityOnRestoreInstanceState(activity, r.state);
                    }
                }
				//执行Activity的onPostCreate()
                if (!r.activity.mFinished) {
                    activity.mCalled = false;
                    if (r.isPersistable()) {
                        mInstrumentation.callActivityOnPostCreate(activity, r.state,
                                r.persistentState);
                    } else {
                        mInstrumentation.callActivityOnPostCreate(activity, r.state);
                    }
                }
            }
            r.paused = true;

            mActivities.put(r.token, r);

        return activity;
    }

这里面执行了Activity的onAttach(),onCreate(),onStart(),onRestoreInstance(),onPostCreate()方法

调用流程,如下图
源码分析:Activity生命周期调用顺序(二)_第1张图片

【注:3】 handleResumeActivity()方法

final void handleResumeActivity(IBinder token,
            boolean clearHide, boolean isForward, boolean reallyResume, int seq, String reason) {
        ActivityClientRecord r = mActivities.get(token);
        if (!checkAndUpdateLifecycleSeq(seq, r, "resumeActivity")) {
            return;
        }

        unscheduleGcIdler();
        mSomeActivitiesChanged = true;

        // 【注:4】执行onResume
        r = performResumeActivity(token, clearHide, reason);

        if (r != null) {
            final Activity a = r.activity;



            final int forwardBit = isForward ?
                    WindowManager.LayoutParams.SOFT_INPUT_IS_FORWARD_NAVIGATION : 0;


            boolean willBeVisible = !a.mStartedActivity;
            if (!willBeVisible) {
                try {
                    willBeVisible = ActivityManager.getService().willActivityBeVisible(
                            a.getActivityToken());
                } catch (RemoteException e) {
                    throw e.rethrowFromSystemServer();
                }
            }
			//这里是处理Activity的View显示的,以后会分析
            if (r.window == null && !a.mFinished && willBeVisible) {
                r.window = r.activity.getWindow();
                View decor = r.window.getDecorView();
                decor.setVisibility(View.INVISIBLE);
                ViewManager wm = a.getWindowManager();
                WindowManager.LayoutParams l = r.window.getAttributes();
                a.mDecor = decor;
                l.type = WindowManager.LayoutParams.TYPE_BASE_APPLICATION;
                l.softInputMode |= forwardBit;
                if (r.mPreserveWindow) {
                    a.mWindowAdded = true;
                    r.mPreserveWindow = false;
                    ViewRootImpl impl = decor.getViewRootImpl();
                    if (impl != null) {
                        impl.notifyChildRebuilt();
                    }
                }
                if (a.mVisibleFromClient) {
                    if (!a.mWindowAdded) {
                        a.mWindowAdded = true;
                        wm.addView(decor, l);
                    } else {
                        // The activity will get a callback for this {@link LayoutParams} change
                        // earlier. However, at that time the decor will not be set (this is set
                        // in this method), so no action will be taken. This call ensures the
                        // callback occurs with the decor set.
                        a.onWindowAttributesChanged(l);
                    }
                }

            } else if (!willBeVisible) {
                if (localLOGV) Slog.v(
                    TAG, "Launch " + r + " mStartedActivity set");
                r.hideForNow = true;
            }

            // Get rid of anything left hanging around.
            cleanUpPendingRemoveWindows(r, false /* force */);

            // The window is now visible if it has been added, we are not
            // simply finishing, and we are not starting another activity.
            if (!r.activity.mFinished && willBeVisible
                    && r.activity.mDecor != null && !r.hideForNow) {
                if (r.newConfig != null) {
                    performConfigurationChangedForActivity(r, r.newConfig);
                    if (DEBUG_CONFIGURATION) Slog.v(TAG, "Resuming activity "
                            + r.activityInfo.name + " with newConfig " + r.activity.mCurrentConfig);
                    r.newConfig = null;
                }
                WindowManager.LayoutParams l = r.window.getAttributes();
                if ((l.softInputMode
                        & WindowManager.LayoutParams.SOFT_INPUT_IS_FORWARD_NAVIGATION)
                        != forwardBit) {
                    l.softInputMode = (l.softInputMode
                            & (~WindowManager.LayoutParams.SOFT_INPUT_IS_FORWARD_NAVIGATION))
                            | forwardBit;
                    if (r.activity.mVisibleFromClient) {
                        ViewManager wm = a.getWindowManager();
                        View decor = r.window.getDecorView();
                        wm.updateViewLayout(decor, l);
                    }
                }

                r.activity.mVisibleFromServer = true;
                mNumVisibleActivities++;
                if (r.activity.mVisibleFromClient) {
                    r.activity.makeVisible();
                }
            }

            if (!r.onlyLocalRequest) {
                r.nextIdle = mNewActivities;
                mNewActivities = r;
                if (localLOGV) Slog.v(
                    TAG, "Scheduling idle handler for " + r);
                Looper.myQueue().addIdleHandler(new Idler());
            }
            r.onlyLocalRequest = false;

            // Tell the activity manager we have resumed.
            if (reallyResume) {
                try {
                    ActivityManager.getService().activityResumed(token);
                } catch (RemoteException ex) {
                    throw ex.rethrowFromSystemServer();
                }
            }

        } else {
            // 当Activity执行onResume时候出现异常,就直接关闭它
            try {
                ActivityManager.getService()
                    .finishActivity(token, Activity.RESULT_CANCELED, null,
                            Activity.DONT_FINISH_TASK_WITH_ACTIVITY);
            } catch (RemoteException ex) {
                throw ex.rethrowFromSystemServer();
            }
        }
    }

这个放出除了调用了,接下来要【注:4】performResumeActivity()方法,还处理了Activity显示View的逻辑。这里,我们只看需要打开的Activity的声明周期调用。接下来,看【注:4】。

【注:4】performResumeActivity()方法

public final ActivityClientRecord performResumeActivity(IBinder token,
            boolean clearHide, String reason) {
        ActivityClientRecord r = mActivities.get(token);
        if (r != null && !r.activity.mFinished) {
				//...省略代码
				//
                r.activity.performResume();
				//...省略代码
            
        }
        return r;
    }

调用activity的performResume();

final void performResume() {
		//1,执行performRestart
        performRestart();
		
		//...省略代码

        mCalled = false;
        // 2,通过Instrumentation调用onResume
        mInstrumentation.callActivityOnResume(this);
        //3,执行onPostResume()方法
		onPostResume();
    }

1,执行performRestart()方法都做了什么

final void performRestart() {
		//...省略代码
		//如果mStopped为true的话。会执行下面onRestart()方法
		//后面我们早onStop()之后,mStopped会置为true
        if (mStopped) {
            mStopped = false;

            mCalled = false;
			//调用activity的onRestart()方法
            mInstrumentation.callActivityOnRestart(this);
            if (!mCalled) {
                throw new SuperNotCalledException(
                    "Activity " + mComponent.toShortString() +
                    " did not call through to super.onRestart()");
            }
			//...省略代码
            performStart();
        }
    }

这个方法,都是只有在,mStopped=true的情况下才会执行。
这里的mStopped其实在Activity的onStop()方法才会置为true,执行了onRestart(),
最后调用了performStart()这个方法

final void performStart() {
        mActivityTransitionState.setEnterActivityOptions(this, getActivityOptions());
		//调用了Instrumentation.callActivityOnStart(this);
        mInstrumentation.callActivityOnStart(this);
		//省略代码

这里执行了onStart()方法。
到这里,我们结合上面mStopped变量,就知道了performRestart()方法执行的流程。onStop()-onRestart()-onStart(),就是在跳转Activity,返回的时候,执行的。
最后,看下Instrumentation里面的方法。我们发现,其实Activity的声明周期都是通过Instrumentation类来实现的。

public class Instrumentation {
	public void callActivityOnResume(Activity activity) {
        activity.mResumed = true;
        //这里看到,最终调用了onResume()
		activity.onResume();
        
    }
	 public void callActivityOnRestart(Activity activity) {
     	//调用onRestart
   		activity.onRestart();
    }
    public void callActivityOnStart(Activity activity) {
        activity.onStart();
    }
}

handleResumeActivity()方法的流程图
源码分析:Activity生命周期调用顺序(二)_第2张图片

到这里就全部看完了。通过分析可以看到Activity的声明周期调用都是通过Instrumentation来调用的。

从ActivityThread.H的LAUNCH_ACTIVITY消息的执行流程图。

源码分析:Activity生命周期调用顺序(二)_第3张图片

你可能感兴趣的:(Android-源码分析,Android,源码分析,Activity,生命周期,ActivityThread)