Android加载时显示Splash-Screen

Question

我有一个Android应用程序,显示3秒的"启动画面".之后,MainActivity被加载.

不幸的是,MainActivity需要额外的约4秒才能加载.在第一次启动时甚至更长.但是,当应用程序加载时,一切运行顺利.

现在,如何在Splash Screen的显示期间实现MainActivity的加载？它应该显示一个图像,直到整个东西完全加载.我已经阅读了有关Async-Task的内容,但我不知道该放在哪里以及如何正确使用它.有谁可以帮助我吗？

SplashScreen.java

public class SplashScreen extends Activity {
    private static int SPLASH_TIME_OUT = 3000;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_startup);

        new Handler().postDelayed(new Runnable() {
            @Override
            public void run() {
                Intent i = new Intent(SplashScreen.this, MainActivity.class);
                startActivity(i);
                finish();
            }
        }, SPLASH_TIME_OUT);
    }
}

MainActivity.java

public class MainActivity extends Activity implements OnClickListener, MediaController.MediaPlayerControl {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //Some heavy processing
        //starting services
        //starting Google Text to Speech
        //and so on...

    }

}

Answer 1

您不应该在启动时创建新线程,而是应该创建一个不必等待资源加载的视图,如本文所述:Splash Screens the Right Way.

如本文所述,您应该创建一个layer-listdrawable而不是layoutXML文件:

<layer-list xmlns:android="http://schemas.android.com/apk/res/android">

    <!-- Fill the background with a solid color -->
    <item android:drawable="@color/gray"/>

    <!-- Place your bitmap in the center -->
    <item>
        <bitmap
            android:gravity="center"
            android:src="@mipmap/ic_launcher"/>
    </item>

</layer-list>

然后使用可绘制文件作为背景创建主题.我使用background属性而不是windowBackground文章中建议的属性,因为background考虑了状态和导航栏,更好地使drawable居中.我也设置windowAnimationStyle为null使闪屏不会转换为MainActivity:

<resources>

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

    <!-- Splash Screen theme -->
    <style name="SplashTheme" parent="Theme.AppCompat.NoActionBar">
        <item name="android:background">@drawable/background_splash</item>
        <item name="android:windowAnimationStyle">@null</item>
    </style>

</resources>

然后在清单中声明您的主题SplashActivity:

<activity android:name=".SplashActivity"
    android:theme="@style/SplashTheme">
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />

        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
</activity>

最后你需要做的SplashActivity只是启动你的MainActivity,启动画面只会显示你的应用程序配置所需的时间:

public class SplashActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        Intent intent = new Intent(this, MainActivity.class);
        startActivity(intent);
        finish();
    }
}

Answer 2

如果对显示启动画面的时间没有特定限制,您可以AsyncTask按以下方式使用:

public class SplashScreen extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_startup);
        startHeavyProcessing();

    }

    private void startHeavyProcessing(){
       new LongOperation().execute("");
    }

    private class LongOperation extends AsyncTask<String, Void, String> {

        @Override
        protected String doInBackground(String... params) {
            //some heavy processing resulting in a Data String
            for (int i = 0; i < 5; i++) {
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    Thread.interrupted();
                }
            }
            return "whatever result you have";
        }

        @Override
        protected void onPostExecute(String result) {
            Intent i = new Intent(SplashScreen.this, MainActivity.class);
            i.putExtra("data", result);
            startActivity(i);
            finish();
        }

        @Override
        protected void onPreExecute() {}

        @Override
        protected void onProgressUpdate(Void... values) {}
    }
}

如果结果数据的性质不是String,那么您可以将ParcelableObject作为额外的活动.在onCreate你可以检索数据:

getIntent().getExtras.getString('data');