参考文章： https://blog.csdn.net/fengyuzhengfan/article/details/52712829
本文主要是针对Android白屏问题，记录解决方案。IOS传送阵。

出现白屏的原因是js.bundle文件未加载完。解决的思路：通过原生代码实现白屏上显示一个Dialog，当js.bundle文件加载完后，在JS代码中将Dialog隐藏。

原生部分

原生部分主要是实现Dialog，显示Dialog和JS调用Dialog隐藏的桥接。原生部分项目结构如下图：

image.png

SplashScreen：创建Diaolg，当白屏的时候显示用。
SplashScreenModule、SplashScreenReactPackage：Dialog关闭的桥接，需要在MainApplication中注册。
welcome.png:Dialog布局文件显示的图片
splash.xml:Dialog加载的布局文件

SplashScreen.java

public class SplashScreen {

    private static int NULL_ID = 0;
    private static Dialog mSplashDialog;
    private static WeakReference<Activity> mActivity;

    /**
     * 打开启动屏
     */
    public static void show(final Activity activity, final boolean fullScreen, final int themeResId){
        if (activity==null) return;
        mActivity = new WeakReference<Activity>(activity);
        activity.runOnUiThread(new Runnable() {
            @Override
            public void run() {
                if (!activity.isFinishing()) {
                    mSplashDialog = new Dialog(
                            activity,
                            themeResId !=NULL_ID ? themeResId
                                    : fullScreen ? R.style.SplashScreen_Fullscreen
                                    : R.style.SplashScreen_SplashTheme

                    );
                    mSplashDialog.setContentView(R.layout.splash);
                    mSplashDialog.setCancelable(false);
                    if (!mSplashDialog.isShowing()) {
                        mSplashDialog.show();
                    }
                }
            }
        });
    }

    /**
     * 打开启动屏
     */
    public static void show(final Activity activity, final boolean fullScreen) {
        show(activity, fullScreen, 0);
    }

    /**
     * 打开启动屏
     */
    public static void show(final Activity activity) {
        show(activity, false);
    }

    /**
     * 关闭启动屏
     */
    public static void hide(Activity activity) {
        if (activity == null) {
            if (mActivity == null) {
                return;
            }
            activity = mActivity.get();
        }
        if (activity == null) return;

        activity.runOnUiThread(new Runnable() {
            @Override
            public void run() {
                if (mSplashDialog != null && mSplashDialog.isShowing()) {
                    mSplashDialog.dismiss();
                    mSplashDialog = null;
                }
            }
        });
    }

}

SplashScreenModule.java

public class SplashScreenModule extends ReactContextBaseJavaModule {
    public SplashScreenModule(ReactApplicationContext reactContext) {
        super(reactContext);
    }

    @Override
    public String getName() {
        return "SplashScreen";
    }

    /**
     * 打开启动屏
     */
    @ReactMethod
    public void show() {
        SplashScreen.show(getCurrentActivity());
    }

    /**
     * 关闭启动屏
     */
    @ReactMethod
    public void hide() {
        SplashScreen.hide(getCurrentActivity());
    }

    /**
     * 退出程序
     */
    @ReactMethod
    public void exit() {
        if (getCurrentActivity() != null)
            getCurrentActivity().finish();
        System.exit(0);
    }

}

styles.xml

<resources>

    <!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
        <!-- Customize your theme here. -->
    </style>

    <style name="SplashScreen_SplashAnimation">
        <item name="android:windowExitAnimation">@android:anim/fade_out</item>
    </style>

    <style name="SplashScreen_SplashTheme" parent="Theme.AppCompat.NoActionBar">
        <item name="android:windowAnimationStyle">@style/SplashScreen_SplashAnimation</item>
    </style>
    <style name="SplashScreen_Fullscreen" parent="SplashScreen_SplashTheme">
        <item name="android:windowFullscreen">true</item>
    </style>

</resources>

MainActivity.java
关键代码：SplashScreen.show(this,true)，并且必须在super.onCreate(savedInstanceState)之前调用。

public class MainActivity extends ReactActivity {

    @Override
    protected String getMainComponentName() {
        return "PushDemo";
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        SplashScreen.show(this,true);//显示Dialog
        super.onCreate(savedInstanceState);
        //解决应用程序多次重启问题
        if ((getIntent().getFlags() & Intent.FLAG_ACTIVITY_BROUGHT_TO_FRONT) != 0){
            finish();
            return;
        }
    }
}

JS部分

该部分比较简单，直接上代码
SplashNative.js

import {NativeModules, Platform} from 'react-native';

const splash = (Platform.OS === "android") ? NativeModules.SplashScreen : {};

export default splash;

关键点是何时隐藏dialog
在js的第一个页面的componentDidMount方法中调用

    import SplashScreen from '../native/SplashNative'     
    ...
    componentDidMount() {
        if(Platform.OS === 'android') {
            SplashScreen.hide();
        }
    }

到此，就完成了白屏问题的解决。

注：原来npm库中react-native-splash-screen已经解决该问题，其原理一样。