如何实现Android应用的启动画面(闪屏)?

Android的启动画面通常用来显示用户的某种形式的进度，在应用程序加载完全之前。有些人使用应用程序的启动动画，只是为了在几秒钟内显示其程序应用和公司的LOGO。不幸的是，和IOS相比，在Android中，我们没有任何内在的机制来显示启动画面。在本教程中，我们将学习如何实现Android应用程序的闪屏。

启动画面的应用场景

启动画面的目的，取决于应用程序的要求。在本教程中，我将讲解实现闪屏的两种实现场景。第一个是使用Timer来显示启动画面，第二个是在进行网络HTTP调用这需要一些时间来获取所需的信息时显示启动画面。这两个教程都是一样的，除了闪屏活动。为了实现闪屏,我们要创建一个单独Activity,一旦这个Activity关闭,我们就启动我们的主Activity.所以首先让我们创建一个新的项目.

1.使用Timer的Android启动画面

1)首先为启动画面创建一个单独的Activity,在新建的项目里新建一个类,命名为SplashScreen.Java.

2)打开你的AndroidManifest.xml文件,让SplashScreen Activity作为启动的Activity.

3)为SplashScreen在res目录下创建一个layout文件,命名为activity_splash.xml,这个Layout只包含你的应用LOGO和公司LOGO.

activity_splash.xml<?xml version="1.0" encoding="utf-8"?>

4)在SplashScreen.Java Activity中添加以下代码,在下面的代码中Handler被用于等待特定的时间,一旦timer时间用完,我们就启动主Activity.

SplashScreen.javapackage com.androidsplashscreentimer; import android.app.Activity;import android.content.Intent;import android.os.Bundle;import android.os.Handler; public class SplashScreen extends Activity {     // Splash screen timer    private static int SPLASH_TIME_OUT = 3000;     @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_splash);         new Handler().postDelayed(new Runnable() {             /*             * Showing splash screen with a timer. This will be useful when you             * want to show case your app logo / company             */             @Override            public void run() {                // This method will be executed once the timer is over                // Start your app main activity                Intent i = new Intent(SplashScreen.this, MainActivity.class);                startActivity(i);                 // close this activity                finish();            }        }, SPLASH_TIME_OUT);    } }

5)启动这个程序,你将会看到3s的闪屏,而且之后你的主Activity也会被启动.

接下来是第二个场景,我们的应用程序在进入主Activity之前会进行一些网络请求.在这里所有的步骤都与之前相同,除了SplashScreen.Java的代码.在SplashScreen.Java的onCreat()方法中我将使用Asynctask方法请求网络获取需要的信息.一旦网络请求终止,就在onPostExecute()方法中启动主Activity.

2.进行网络请求时的Android闪屏

1)依照上面的步骤创建SplashScreen.Java类. 2)在AndroidManifest.xml文件中添加 INTERNET 权限.

3)在SplashScreen.Java中添加AsyncTask方法请求网络.在本教程中将通过HTTP调用来获取JSON并用log形式显示在屏幕.获取Json数据之后通过Intent传值到MainActivity中.

SplashScreen.javapackage info.androidhive.androidsplashscreentimer; import info.androidhive.androidsplashscreennetwork.R;import info.androidhive.network.JsonParser; import org.json.JSONException;import org.json.JSONObject; import android.app.Activity;import android.content.Intent;import android.os.AsyncTask;import android.os.Bundle;import android.util.Log; public class SplashScreen extends Activity {     String now_playing, earned;     @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_splash);         /**         * Showing splashscreen while making network calls to download necessary         * data before launching the app Will use AsyncTask to make http call         */        new PrefetchData().execute();     }     /**     * Async Task to make http call     */    private class PrefetchData extends AsyncTask {         @Override        protected void onPreExecute() {            super.onPreExecute();            // before making http calls                  }         @Override        protected Void doInBackground(Void... arg0) {            /*             * Will make http call here This call will download required data             * before launching the app              * example:              * 1. Downloading and storing in SQLite              * 2. Downloading images              * 3. Fetching and parsing the xml / json              * 4. Sending device information to server              * 5. etc.,             */            JsonParser jsonParser = new JsonParser();            String json = jsonParser                    .getJSONFromUrl("http://api.androidhive.info/game/game_stats.json");             Log.e("Response: ", "> " + json);             if (json != null) {                try {                    JSONObject jObj = new JSONObject(json)                            .getJSONObject("game_stat");                    now_playing = jObj.getString("now_playing");                    earned = jObj.getString("earned");                     Log.e("JSON", "> " + now_playing + earned);                 } catch (JSONException e) {                    // TODO Auto-generated catch block                    e.printStackTrace();                }             }             return null;        }         @Override        protected void onPostExecute(Void result) {            super.onPostExecute(result);            // After completing http call            // will close this activity and lauch main activity            Intent i = new Intent(SplashScreen.this, MainActivity.class);            i.putExtra("now_playing", now_playing);            i.putExtra("earned", earned);            startActivity(i);             // close this activity            finish();        }     } }

MainActivity.javapackage com.androidsplashscreentimer; import com.androidsplashscreennetwork.R;import android.app.Activity;import android.content.Intent;import android.os.Bundle;import android.view.View;import android.widget.LinearLayout;import android.widget.TextView; public class MainActivity extends Activity {     LinearLayout llStats;    TextView txtPlayCount, txtEarned;     @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);         llStats = (LinearLayout) findViewById(R.id.llStats);        txtPlayCount = (TextView) findViewById(R.id.txtNowPlaying);        txtEarned = (TextView) findViewById(R.id.txtEarned);         // layout background transparent        llStats.getBackground().setAlpha(150);        llStats.setVisibility(View.VISIBLE);         Intent i = getIntent();        String now_playing = i.getStringExtra("now_playing");        String earned = i.getStringExtra("earned");         // Diplaying the text        txtPlayCount.setText(now_playing);        txtEarned.setText(earned);    }}

1.使用Timer的Android启动画面

2.进行网络请求时的Android闪屏

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