Android启动过程中背景图片显示

大部分Android App启动过程中，都会设置一个背景图片，直到App加载成功，图片消失。因此，这也是做Android App的基本技能之一。这个过程实现起来并不难。

总共需要以下内容：2个Activity，一张背景图，2个xml配置文件，String.xml，AndroidManifest写入配置信息。

1 准备一张背景图图片,命名为load,自己选择图片格式。放在drawable目录下

2  创建Load页面 LoadActivity.java及相关布局文件load.xml

LoadActivity.java

package com.timothy.load;

import android.app.Activity;
import android.os.Bundle;
import android.content.Intent;
import android.graphics.PixelFormat;
import android.os.Handler;
import android.view.WindowManager;

public class LoadActivity extends Activity {

    //time for picture display
    private static final int LOAD_DISPLAY_TIME = 1500;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        getWindow().setFormat(PixelFormat.RGBA_8888);
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_DITHER);
        setContentView(R.layout.load);

        new Handler().postDelayed(new Runnable() {
            public void run() {
                //Go to main activity, and finish load activity
                Intent mainIntent = new Intent(LoadActivity.this, MainActivity.class);
                LoadActivity.this.startActivity(mainIntent);
                LoadActivity.this.finish();
            }
        }, LOAD_DISPLAY_TIME);
    }
}

load.xml

<?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:orientation="vertical"
     android:gravity="center|center"
     android:layout_width="fill_parent"
     android:layout_height="fill_parent"
     android:background="@drawable/load">
 </LinearLayout>

3  创建主页面 MainActivity.java及相关布局文件main.xml 

MainActivity.java

package com.timothy.load;

import android.app.Activity;
import android.os.Bundle;

public class MainActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
    }
}

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="@string/hello"
    />
</LinearLayout>

4 配置strings.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="hello">Hello, this is a demo to picture before app start</string>
    <string name="app_name">LoadPictureDemo</string>

    <style name="MyTheme.NoTitleBar.CustomBackground" parent="@android:Theme.Black">
        <item name="android:windowBackground">@drawable/load</item>
        <item name="android:windowNoTitle">true</item>
        <item name="android:windowFullscreen">true</item>
        <item name="android:windowContentOverlay">@null</item>
    </style>
</resources>

5 配置AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.timothy.load"
      android:versionCode="1"
      android:versionName="1.0">
    <uses-sdk android:minSdkVersion="8" />

    <application android:icon="@drawable/icon" android:label="@string/app_name">

         <activity android:name=".LoadActivity"
                  android:configChanges="orientation|keyboardHidden"
                  android:theme="@style/MyTheme.NoTitleBar.CustomBackground">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <activity android:name=".MainActivity">
        </activity>

    </application>
</manifest>

6 OK, 编译运行

启动过程中：

完成启动：