activity_splash.xml:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#99cc00">

    <TextView
        android:id="@+id/tv_version"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:textColor="#ffffff"
        android:textSize="14sp"/>

</RelativeLayout>

SplashActivity.java:

package com.example.muzico.test.activity;

import android.app.Activity;
import android.content.Intent;
import android.content.pm.ActivityInfo;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.widget.TextView;

import com.example.muzico.test.MainActivity;
import com.example.muzico.test.R;

import java.util.Timer;
import java.util.TimerTask;

public class SplashActivity extends Activity {

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

        setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);

        init();
    }

    private void init() {

        //设置启动页的版本信息
        TextView textView = findViewById(R.id.tv_version);
        try {
            PackageInfo info = getPackageManager().getPackageInfo(getPackageName(),0);
            textView.setText("V" + info.versionName);

        } catch (PackageManager.NameNotFoundException e) {
            e.printStackTrace();
            textView.setText("V");
        }


        Timer timer = new Timer();
        TimerTask task = new TimerTask() {
            @Override
            public void run() {
                Intent intent = new Intent(SplashActivity.this, MainActivity.class);
                startActivity(intent);
                SplashActivity.this.finish();
            }
        };
        timer.schedule(task, 3000);//定时器延迟3秒后执行
    }
}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.muzico.test">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.AppCompat.NoActionBar">
        <activity android:name=".MainActivity">

        </activity>
        <activity android:name=".activity.SplashActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

全屏效果：

res/values/styles.xml:

<resources>

    <style name="AppTheme.Full" parent="Theme.AppCompat.NoActionBar">
        <item name="android:windowFullscreen">true</item>
    </style>

</resources>

AndroidManifest.xml 中 android:theme 的值改为：

@style/AppTheme.Full

可以看到 启动页变成了全屏，而主页也是。。。变成了全屏。

隐藏、显示状态栏

为了让主页里面可以看到状态栏，我们可以在主页里面使用代码：

MainActivity.java:

package com.example.muzico.test;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.WindowManager;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        //显示状态栏
        getWindow().clearFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);
    }
}

知识点：

//隐藏状态栏 
getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);
//显示状态栏
getWindow().clearFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);

更加简单的启动页全屏

在上面我们看到有代码可以直接隐藏、显示状态栏，那么我们是否不修改 AndroidManifest.xml、MainActivity.java 的情况下，直接让启动页全屏而有不影响主页呢？

答案是可以的。

SplashActivity.java:

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

        //隐藏状态栏
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);

        setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);

        init();
    }