一、概述：

壁纸运行在一个Android服务之中，这个服务的名字叫做WallpaperService。当用户选择了一个壁纸之后，此壁纸所对应的WallpaperService便会启动并开始进行壁纸的绘制工作。

Engine是WallpaperService中的一个内部类，实现了壁纸窗口的创建以及Surface的维护工作。Engine内部实现了SurfaceView，我们只需要在其内部利用MediaPlayer + SurfaceView就可以播放动态壁纸了。

二、实现：

WallpaperService需要一个xml去配置，然后在AndroidManifest.xml中声明

android:thumbnail="@mipmap/icon_lacation_black___cm">

继承WallpaperService实现我们自己的壁纸服务VideoLiveWallpaper

public class VideoLiveWallpaper extends WallpaperService {

@Override

public Engine onCreateEngine() {

return new VideoEngine();

}

class VideoEngine extends Engine {

private MediaPlayer mMediaPlayer;

@Override

public void onCreate(SurfaceHolder surfaceHolder) {

super.onCreate(surfaceHolder);

}

@Override

public void onDestroy() {

super.onDestroy();

}

@Override

public void onSurfaceCreated(SurfaceHolder holder) {

super.onSurfaceCreated(holder);

mMediaPlayer = new MediaPlayer();

mMediaPlayer.setSurface(holder.getSurface());

try {

mMediaPlayer.setDataSource(new File(FileUtil.getDCIMCameraDir(), "hlj_wallpaper").getAbsolutePath());

mMediaPlayer.setLooping(true);

mMediaPlayer.setVolume(0, 0);

mMediaPlayer.prepare();

mMediaPlayer.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {

@Override

public void onPrepared(MediaPlayer mp) {

mMediaPlayer.start();

}

});

} catch (IOException e) {

e.printStackTrace();

}

}

@Override

public void onSurfaceDestroyed(SurfaceHolder holder) {

super.onSurfaceDestroyed(holder);

mMediaPlayer.release();

mMediaPlayer = null;

}

@Override

public void onVisibilityChanged(boolean visible) {

if (visible) {

mMediaPlayer.start();

} else {

mMediaPlayer.pause();

}

}

}

}

接着声明这个服务同时声明我们上面写的xml配置

android:name=".VideoLiveWallpaper"

android:label="@string/app_name"

android:permission="android.permission.BIND_WALLPAPER"

android:process=":wallpaper">

android:name="android.service.wallpaper"

android:resource="@xml/wallpaper" />

重点在onSurfaceCreated方法中，这里为了可以动态切换不同的壁纸，我是指定去加载一个固定目录下的视频文件，然后不断的复制新文件到这个目录，因为一旦开启切换壁纸这个方法就会调用，所以当调用后再动态通知去更改路径不起作用。

所以我在更换壁纸前先清空

try {

WallpaperManager.getInstance(getContext())

.clear();

} catch (IOException e) {

e.printStackTrace();

}

再去复制需要替换的壁纸到指定目录

copyFile(file.getAbsolutePath(),

new File(FileUtil.getDCIMCameraDir(),

"hlj_wallpaper").getAbsolutePath());

/**

* 复制单个文件

*

* @param oldPath String 原文件路径 如：c:/fqf.txt

* @param newPath String 复制后路径 如：f:/fqf.txt

* @return boolean

*/

public void copyFile(final String oldPath, final String newPath) {

progressBar.setVisibility(View.VISIBLE);

Observable.create(new Observable.OnSubscribe() {

@Override

public void call(Subscriber super Boolean> subscriber) {

try {

int byteSum = 0;

int byteRead ;

File oldFile = new File(oldPath);

if (oldFile.exists()) { //文件存在时

InputStream inStream = new FileInputStream(oldPath); //读入原文件

FileOutputStream fs = new FileOutputStream(newPath);

byte[] buffer = new byte[1444];

while ((byteRead = inStream.read(buffer)) != -1) {

byteSum += byteRead; //字节数 文件大小

System.out.println(byteSum);

fs.write(buffer, 0, byteRead);

}

inStream.close();

subscriber.onNext(true);

subscriber.onCompleted();

}

} catch (Exception e) {

System.out.println("复制单个文件操作出错");

e.printStackTrace();

subscriber.onCompleted();

}

}

})

.subscribeOn(Schedulers.io())

.observeOn(AndroidSchedulers.mainThread())

.subscribe(new Observer() {

@Override

public void onCompleted() {

progressBar.setVisibility(View.GONE);

}

@Override

public void onError(Throwable e) {

progressBar.setVisibility(View.GONE);

}

@Override

public void onNext(Boolean aBoolean) {

progressBar.setVisibility(View.GONE);

setToWallPaper(getContext());

}

});

}

setToWallPaper方法就是真正的开启设置壁纸操作了

public static void setToWallPaper(Context context) {

final Intent intent = new Intent(WallpaperManager.ACTION_CHANGE_LIVE_WALLPAPER);

intent.putExtra(WallpaperManager.EXTRA_LIVE_WALLPAPER_COMPONENT,

new ComponentName(context, VideoLiveWallpaper.class));

context.startActivity(intent);

}

至此，一个简单的动态壁纸就搞定了。