Android性能优化第（九）篇---App启动速度优化之启动页设计

在上篇文章Android性能优化第（八）篇---App启动速度优化之耗时检测处理说了应用启动的拦路虎在哪里，最后给出了优化思路，如果经过第一轮的优化之后，还是不满意的话，一般我们是做个启动页，因为启动页一般View的数量比较少，业务逻辑比较简单，启动就不太费劲。

一、设计思路

• 常规启动页设计思路

通常点击桌面就会执行，Application中的逻辑，这部分的逻辑优化技巧在上篇介绍过，然后会跳入启动页SplashActivity,通常展示一个图片和logo,然后2或3秒后，并且SplashActivity里面可以去做一些MainActivity的数据的预加载，然后需要通过意图传到MainActivity。
优点：启动速度有所加快
缺点：最终还是要进入首页，在进入首页的时候，首页复杂的View渲染以及必须在UI线程执行的业务逻辑，仍然拖慢了启动速度。启动页简单执行快，首页复杂执行慢，前轻后重。

期待：能否在启动页的展示的同时，首页的View就能够被加载，首页的业务逻辑就能够被执行？

• 优化的启动页的设计思路

为了在展示启动页的同时，也能渲染首页，把SplashActivity改成SplashFragment,应用程序的入口仍然是MainActivity,在MainActivity中先展示SplashFragment，当SplashFragment显示完毕后再将它remove，同时在SplashFragment的2S的友好时间内进行网络数据缓存，在窗口加载完毕后，我们加载activity_main的布局，考虑到这个布局有可能比较复杂，耽误View的解析时间，采用ViewStub的形式进行懒加载。这样一开始只要加载SplashFragment所展示的布局就Ok了。

二、实现

MainActivity .java

public class MainActivity extends FragmentActivity {

    private  MyHandler mHandler=new MyHandler(this);

    public static final String TAG="MainActivity";

    private ProgressBar mNetLoadingBar;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.d(TAG,"onCreate");
        setContentView(R.layout.activity_main);
        final SplashFragment splashFragment = new SplashFragment();
        final ViewStub mainLayout = (ViewStub) findViewById(R.id.content_viewstub);
        //1、一上来首先显示启动页面
        FragmentManager supportFragmentManager = getSupportFragmentManager();
        if (supportFragmentManager != null) {
            FragmentTransaction fragmentTransaction = supportFragmentManager.beginTransaction();
            if (fragmentTransaction != null) {
                fragmentTransaction.replace(R.id.container, splashFragment);
                fragmentTransaction.commit();
            }
        }

        //2、如果主页有网络等耗时操作，可以现在就开始
        new Thread(new Runnable() {
            @Override
            public void run() {
                //耗时3500
                SystemClock.sleep(3000);
                mHandler.sendEmptyMessage(0);
            }
        }).start();

        //3、渲染完毕后,立刻加载主页布局
        getWindow().getDecorView().post(new Runnable() {
            @Override
            public void run() {
                Log.d(TAG," getWindow().getDecorView().post");
                View mainView = mainLayout.inflate();
                initView(mainView);
            }
        });

        //4、 启动页有动画，延迟一下,播放完动画，执行remove
        getWindow().getDecorView().post(new Runnable() {
            @Override
            public void run() {
                mHandler.postDelayed(new DelayRunnableImpl(MainActivity.this, splashFragment), 2000);
            }
        });
    }

    @Override
    protected void onResume() {
        super.onResume();
        Log.d(TAG,"onResume");
    }

    /**
     * 初始化主页View
     */
    private void initView(View pMainView) {
        if (pMainView != null) {
            mNetLoadingBar = (ProgressBar) pMainView.findViewById(R.id.progressbar);
            mNetLoadingBar.setVisibility(View.VISIBLE);
        }
    }


    private static class MyHandler extends Handler {

        private WeakReference wRef;

        private MyHandler(MainActivity pActivity) {
            this.wRef = new WeakReference(pActivity);
        }

        @Override
        public void handleMessage(Message msg) {
            MainActivity mainActivity = wRef.get();
            if (mainActivity != null) {
                mainActivity.mNetLoadingBar.setVisibility(View.GONE);
            }
        }
    }

    private class DelayRunnableImpl implements Runnable {
        WeakReference contextWref;
        WeakReference fragmentWref;

        private DelayRunnableImpl(Context pContext, Fragment pFragment) {
            this.contextWref = new WeakReference<>(pContext);
            this.fragmentWref = new WeakReference<>(pFragment);
        }

        @Override
        public void run() {
            FragmentActivity context = (FragmentActivity) contextWref.get();
            if (context != null) {
                FragmentManager supportFragmentManager = context.getSupportFragmentManager();
                if (supportFragmentManager != null) {
                    FragmentTransaction fragmentTransaction = supportFragmentManager.beginTransaction();
                    SplashFragment fragment = (SplashFragment) fragmentWref.get();
                    if (fragment != null) {
                        fragmentTransaction.remove(fragment);
                        fragmentTransaction.commit();
                    }
                }
            }
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if (mHandler != null) {
            mHandler.removeCallbacksAndMessages(null);
        }
    }

}

SplashFragment .java

public class SplashFragment extends Fragment {

    public SplashFragment() {

    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View ret = inflater.inflate(R.layout.fragment_splash, container, false);
        initView(ret);
        return ret;
    }

    private void initView(View ret) {
        if (ret != null) {
            ImageView imageView = (ImageView) ret.findViewById(R.id.laucher_logo);
            playAnimator(imageView);
        }
    }

    private void playAnimator(ImageView pView) {
        if (pView != null) {
            PropertyValuesHolder pvhA = PropertyValuesHolder.ofFloat("alpha", 1f, 0.7f, 0.1f);
            //  PropertyValuesHolder pvhR= PropertyValuesHolder.ofFloat("rotationX", 0.0F, 360.0F);
            ObjectAnimator.ofPropertyValuesHolder(pView, pvhA).setDuration(2000).start();
        }
    }
}

activity_mian.xml

fragment.xml

main_layout.xml

效果怎么样呢？

看一下启动时间

C:\Users\wangjing>adb shell am start -W zhangwan.wj.com.myshare/zhangwan.wj.com.myshare.activity.MainActivity
Starting: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] cmp=zhangwan.wj.com.myshare/.activity.MainActivity }
Status: ok
Activity: zhangwan.wj.com.myshare/.activity.MainActivity
ThisTime: 683
TotalTime: 683
Complete

还是挺不错的吧。

参考链接：请不要滥用SharedPreference https://zhuanlan.zhihu.com/p/22913991
Please accept mybest wishes for your happiness and success !