Android視頻壁紙的實(shí)現(xiàn)

視頻壁紙屬于動(dòng)態(tài)壁紙，所以視頻壁紙就可以用Android系統(tǒng)提供的動(dòng)態(tài)壁紙服務(wù)來(lái)實(shí)現(xiàn)。首先先介紹一下在實(shí)現(xiàn)過(guò)程中會(huì)用到的幾個(gè)類。

WallpaperManager

Android提供的用于管理壁紙的類，里面有幾個(gè)方法在實(shí)現(xiàn)過(guò)程中需要用到

  1. getInstance(context) 獲取一個(gè)實(shí)例
  2. clear() 清空所有的壁紙
  3. getWallpaperInfo() 獲取當(dāng)前壁紙的信息

WallpaperService

Android系統(tǒng)提供的壁紙服務(wù)的抽象類，實(shí)現(xiàn)一個(gè)動(dòng)態(tài)壁紙必須要繼承該類并實(shí)現(xiàn)onCreateEngine()方法，該類的唯一功能就是返回繪制動(dòng)態(tài)壁紙所需要的Engine實(shí)例。

WallpaperService.Engine

Engine是WallpaperService一個(gè)內(nèi)部類，動(dòng)態(tài)壁紙的所有顯示過(guò)程的繪制都由該類完成，我們需要繼承該類并實(shí)現(xiàn)以下三個(gè)方法：

  1. onSurfaceCreated()
  2. onSurfaceDestroyed()
  3. onVisibilityChanged()

當(dāng)然還有其他的如onCreate()和onDestroy()方法等等。

視頻壁紙的實(shí)現(xiàn)過(guò)程

  • 首先我們需要自定義一個(gè)類VideoWallPaperService來(lái)繼承WallpaperService類并實(shí)現(xiàn)onCreateEngine()方法，在該方法中需要返回一個(gè)Engine實(shí)例。
public class VideoWallPaperService extends WallpaperService {
    @Override
    public Engine onCreateEngine() {
        return new VideoEngine();
    }
}
  • 所以我們需要再VideoWallPaperService內(nèi)部自定義一個(gè)VideoEngine類來(lái)繼承Engine類并實(shí)現(xiàn)onSurfaceCreated() 、onSurfaceDestroyed()和onVisibilityChanged()方法。然后在onSurfaceCreated()方法中初始化一個(gè)MediaPlayer；在onSurfaceDestroyed()中去釋放和銷(xiāo)毀MediaPlayer；在onVisibilityChanged()方法中去切換MediaPlayer的播放和暫停。
private class VideoEngine extends Engine {
        private MediaPlayer mPlayer;

        @Override
        public void onVisibilityChanged(boolean visible) {
             if(visible) {
                 mPlayer.start();
             } else {
                 mPlayer.pause();
             }
        }

        @Override
        public void onSurfaceCreated(SurfaceHolder holder) {
            super.onSurfaceCreated(holder);
            mPlayer = new MediaPlayer();
            //不能使用setDisplay()方法
            mPlayer.setSurface(holder.getSurface());
            mPlayer.setDataSource(videoPath);
            mPlayer.prepare();
            mPlayer.start();
        }

        @Override
        public void onSurfaceDestroyed(SurfaceHolder holder) {
            super.onSurfaceDestroyed(holder);
            if(mPlayer.isPlaying()) {
                mPlayer.stop();
            }
            mPlayer.release();
            mPlayer = null;
        }
    }
  • 以上都完成后我們還需要對(duì)VideoWallPaperService進(jìn)行注冊(cè)，這里在注冊(cè)時(shí)寫(xiě)法和普通的Service相同，其中VideoWallPaperService需要一個(gè)"android.permission.BIND_WALLPAPER"的權(quán)限，需要添加一個(gè)action為"android.service.wallpaper.WallpaperService"（固定寫(xiě)法），還需要一個(gè)名為"android.service.wallpaper"（固定寫(xiě)法）的meta-data。
<service
     android:name=".VideoWallPaperService"
     android:permission="android.permission.BIND_WALLPAPER">
     <intent-filter>
          <action android:name="android.service.wallpaper.WallpaperService" />
     </intent-filter>
     <meta-data
           android:name="android.service.wallpaper"
           android:resource="@xml/wallpaper" />
     </service>
  • 上面一步的代碼中meta-data中需要一個(gè)xml文件源，所以我們需要再res的xml文件夾(沒(méi)有就自己建)下創(chuàng)建一個(gè)名為wallpaper的xml文件。xml文件的根標(biāo)簽為wallpaper，有一下三個(gè)屬性:
  1. description 動(dòng)態(tài)壁紙的文字描述
  2. thumbnail 動(dòng)態(tài)壁紙的圖片描述
  3. settingsActivity 動(dòng)態(tài)壁紙的設(shè)置界面（會(huì)在預(yù)覽界面出現(xiàn)）
<?xml version="1.0" encoding="utf-8"?>
<wallpaper xmlns:android="http://schemas.android.com/apk/res/android"
    android:description="@string/wallpaper_description"
    android:settingsActivity="com.example.videowallpaper.SettingsActivity"
    android:thumbnail="@mipmap/ic_launcher">
</wallpaper>
  • 接下來(lái)就是啟動(dòng)壁紙服務(wù)了，這里我們不能通過(guò)context的startService()方法來(lái)啟動(dòng)壁紙服務(wù)，我們需要通過(guò)啟動(dòng)系統(tǒng)的預(yù)覽界面來(lái)間接啟動(dòng)服務(wù)。
Intent intent = new Intent(WallpaperManager.ACTION_CHANGE_LIVE_WALLPAPER);
intent.putExtra(WallpaperManager.EXTRA_LIVE_WALLPAPER_COMPONENT, new ComponentName(context, VideoWallPaperService.class));
context.startActivity(intent);
  • 除了啟動(dòng)還需要關(guān)閉壁紙服務(wù)，我們可以通過(guò)WallpaperManager的clear()方法來(lái)關(guān)閉，也可以通過(guò)WallpaperService的clearWallpaper()(已經(jīng)被標(biāo)記過(guò)時(shí))方法來(lái)關(guān)閉壁紙。
try {
      WallpaperManager.getInstance(context).clear();
} catch(IOException e) {
       e.printStackTrace();
}
  • 其他需要注意的地方
  1. 設(shè)置壁紙需要"android.permission.SET_WALLPAPER"權(quán)限
  2. 播放本地視頻需要"android.permission.READ_EXTERNAL_STORAGE"權(quán)限
  3. VideoEngine的MediaPlayer的播放地址要使用持久化保存數(shù)據(jù)（數(shù)據(jù)庫(kù)、Preference等），否則設(shè)置好視頻壁紙后將手機(jī)關(guān)機(jī)再開(kāi)機(jī)，就會(huì)出bug
  4. WallpaperService的onCreateEngine()方法返回的Engine實(shí)例不能使用單例模式，必須每次都返回一個(gè)新的Engine實(shí)例
  5. 可以通過(guò)WallpaperManager的getWallpaperInfo()方法來(lái)判斷當(dāng)前自己的服務(wù)是否已經(jīng)在運(yùn)行，從而可以通過(guò)廣播或者其他通知來(lái)直接修改壁紙播放的視頻，從而避免每次更換一個(gè)視頻都需要走一次系統(tǒng)的預(yù)覽界面。

最后貼一下VideoWallPaperService的完整代碼（僅供參考）：

package com.example.videowallpaper;

import android.app.WallpaperInfo;
import android.app.WallpaperManager;
import android.content.BroadcastReceiver;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.SharedPreferences;
import android.media.MediaPlayer;
import android.preference.PreferenceManager;
import android.service.wallpaper.WallpaperService;
import android.text.TextUtils;
import android.view.SurfaceHolder;

import java.io.IOException;

public class VideoWallPaperService extends WallpaperService {
    private static final String SERVICE_NAME = "com.example.videowallpaper.VideoWallPaperService";

    @Override
    public Engine onCreateEngine() {
        return new VideoEngine();
    }

    public static void startWallPaper(Context context, String videoPath) {
        WallpaperInfo info = WallpaperManager.getInstance(context).getWallpaperInfo();

        if(info != null && SERVICE_NAME.equals(info.getServiceName())) {
            changeVideo(context, videoPath);
        } else {
            startNewWallpaper(context, videoPath);
        }
    }

    public static void closeWallpaper(Context context) {
        try {
            WallpaperManager.getInstance(context).clear();
        } catch(IOException e) {
            e.printStackTrace();
        }
    }

    private static void startNewWallpaper(Context context, String path) {
        saveVideoPath(context, path);
        Intent intent = new Intent(WallpaperManager.ACTION_CHANGE_LIVE_WALLPAPER);
        intent.putExtra(WallpaperManager.EXTRA_LIVE_WALLPAPER_COMPONENT, new ComponentName(context, VideoWallPaperService.class));
        context.startActivity(intent);
    }

    private static void changeVideo(Context context, String path) {
        saveVideoPath(context, path);
        Intent intent = new Intent();
        intent.setAction(Constant.ACTION);
        intent.putExtra(Constant.BROADCAST_SET_VIDEO_PARAM, Constant.ACTION_SET_VIDEO);
        context.sendBroadcast(intent);
    }

    public static void setVolume(Context context, boolean hasVolume) {
        Intent intent = new Intent();
        intent.setAction(Constant.ACTION);
        if(hasVolume) {
            intent.putExtra(Constant.BROADCAST_SET_VIDEO_PARAM, Constant.ACTION_VOICE_NORMAL);
        } else {
            intent.putExtra(Constant.BROADCAST_SET_VIDEO_PARAM, Constant.ACTION_VOICE_SILENCE);
        }
        context.sendBroadcast(intent);
    }

    private static void saveVideoPath(Context context, String path) {
        SharedPreferences.Editor editor = PreferenceManager.getDefaultSharedPreferences(context).edit();
        editor.putString(Constant.VIDEO_PATH, path);
        editor.apply();
    }

    private String getVideoPath() {
        SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(this);
        return preferences.getString(Constant.VIDEO_PATH, null);
    }

    private class VideoEngine extends Engine implements MediaPlayer.OnPreparedListener,
            MediaPlayer.OnCompletionListener, MediaPlayer.OnErrorListener {
        private MediaPlayer mPlayer;
        private boolean mLoop;
        private boolean mVolume;
        private boolean isPapered = false;

        private VideoEngine() {
            SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(VideoWallPaperService.this);
            mLoop = preferences.getBoolean("loop", true);
            mVolume = preferences.getBoolean("volume", false);
        }

        private BroadcastReceiver mReceiver = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                int action = intent.getIntExtra(Constant.BROADCAST_SET_VIDEO_PARAM, -1);
                switch(action) {
                    case Constant.ACTION_SET_VIDEO: {
                        setVideo(getVideoPath());
                        break;
                    }
                    case Constant.ACTION_VOICE_NORMAL: {
                        mVolume = true;
                        setVolume();
                        break;
                    }
                    case Constant.ACTION_VOICE_SILENCE: {
                        mVolume = false;
                        setVolume();
                        break;
                    }
                }
            }
        };

        @Override
        public void onCreate(SurfaceHolder surfaceHolder) {
            super.onCreate(surfaceHolder);
            IntentFilter filter = new IntentFilter();
            filter.addAction(Constant.ACTION);
            registerReceiver(mReceiver, filter);
        }

        @Override
        public void onDestroy() {
            super.onDestroy();
            unregisterReceiver(mReceiver);
        }

        @Override
        public void onVisibilityChanged(boolean visible) {
            if(isPapered) {
                if(visible) {
                    mPlayer.start();
                } else {
                    mPlayer.pause();
                }
            }
        }

        @Override
        public void onSurfaceCreated(SurfaceHolder holder) {
            super.onSurfaceCreated(holder);
            mPlayer = new MediaPlayer();
            setVideo(getVideoPath());
        }

        @Override
        public void onSurfaceDestroyed(SurfaceHolder holder) {
            super.onSurfaceDestroyed(holder);
            if(mPlayer.isPlaying()) {
                mPlayer.stop();
            }
            mPlayer.release();
            mPlayer = null;
        }

        @Override
        public void onPrepared(MediaPlayer mp) {
            isPapered = true;
            mp.start();
        }

        @Override
        public void onCompletion(MediaPlayer mp) {
            closeWallpaper(getApplicationContext());
        }

        @Override
        public boolean onError(MediaPlayer mp, int what, int extra) {
            closeWallpaper(getApplicationContext());
            return true;
        }

        private void setVideo(String videoPath) {
            if(TextUtils.isEmpty(videoPath)) {
                closeWallpaper(getApplicationContext());
                throw new IllegalArgumentException("video path is null");
            }
            if(mPlayer != null) {
                mPlayer.reset();
                isPapered = false;
                try {
                    mPlayer.setOnPreparedListener(this);
                    mPlayer.setOnCompletionListener(this);
                    mPlayer.setOnErrorListener(this);
                    mPlayer.setLooping(mLoop);
//                  mPlayer.setDisplay(getSurfaceHolder());
                    mPlayer.setSurface(getSurfaceHolder().getSurface());
                    setVolume();
                    mPlayer.setDataSource(videoPath);
                    mPlayer.prepareAsync();
                } catch(IOException e) {
                    e.printStackTrace();
                }
            }
        }

        private void setVolume() {
            if(mPlayer != null) {
                if(mVolume) {
                    mPlayer.setVolume(1.0f, 1.0f);
                } else {
                    mPlayer.setVolume(0f, 0f);
                }
            }
        }
    }
}

還有一個(gè)SettingsActivity的代碼也貼出來(lái)吧

這里說(shuō)明一下推薦使用PreferenceFragment來(lái)代替PreferenceActivity

package com.example.videowallpaper;

import android.os.Bundle;
import android.preference.PreferenceActivity;

public class SettingsActivity extends PreferenceActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        addPreferencesFromResource(R.xml.setting_layout);
    }
}

setting_layout

<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"
    android:key="video_param"
    android:title="設(shè)置">
    <CheckBoxPreference
        android:defaultValue="true"
        android:key="loop"
        android:title="是否循環(huán)播放" />
    <CheckBoxPreference
        android:checked="false"
        android:key="volume"
        android:title="是否開(kāi)啟聲音" />
</PreferenceScreen>

Constant.java（自定義的一些常量）

public class Constant {
    public static final String BROADCAST_SET_VIDEO_PARAM = "broadcast_set_video_param";
    public static final String ACTION = "action";
    public static final String VIDEO_PATH = "action_video_path";
    public static final int ACTION_SET_VIDEO = 0x101;
    public static final int ACTION_VOICE_SILENCE = 0x102;
    public static final int ACTION_VOICE_NORMAL = 0x103;
}
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