设置更新后如何重新启动此壁纸引擎？

我正在创建动态壁纸，并使用本教程作为起点：

http://code.tutsplus.com/tutorials/create-a-live-wallpaper-on-android-using-an-animated-gif--cms-23088 http://code.tutsplus.com/tutorials/create-a-live-wallpaper-on-android-using-an-animated-gif--cms-23088

我正在尝试添加一个设置菜单，让用户选择四种背景之一。我一切都在使用SharedPreferences。唯一的问题是在设置菜单中更改设置后壁纸不会更新。如果您重新启动应用程序，背景将更新为最后选择的背景，但只有在壁纸重新启动后才有效（即选择不同的壁纸，然后重新选择此壁纸）。

我已将问题范围缩小到以下事实：SharedPreference仅更新于onCreateEngine()方法。壁纸服务运行后，onCreateEngine()方法不会被调用，所以即使SharedPreference已更改，它不会在壁纸服务中更新。

我的问题是如何重新启动壁纸以便onCreateEngine()设置更改后调用方法？再次，SharedPreferences正在工作，因为重新启动后一切正常。我知道我需要使用onsharedPreferenceChanged方法，但我不确定应该在哪里发生，或者该方法中应包含哪些代码来重新启动壁纸引擎。

这是示例代码。除了评论指出之外，我的也是一样的：

    import android.graphics.Canvas;
    import android.graphics.Movie;
    import android.os.Handler;
    import android.service.wallpaper.WallpaperService;
    import android.util.Log;
    import android.view.SurfaceHolder;

    import java.io.IOException;

    public class GIFWallpaperService extends WallpaperService implements onsharedpreferencechangelistener {

        // Variable I added to change background
        String mBackgroundImage = null;

        // Method I added to update background image
        public void updatedBackgroundImage(){
             // code that sets mBackgroundImage based upon value of shared preference file. 
        }

        @Override
        public WallpaperService.Engine onCreateEngine() {

            // I call this method to change the value of mBackgroundImage
            updateBackgroundImage(); 

            try {
                Movie movie = Movie.decodeStream(
                        getResources().getAssets().open("mBackgroundImage"));

                return new GIFWallpaperEngine(movie);
            }catch(IOException e){
                Log.d("GIF", "Could not load asset");
                return null;
            }
        }

        @Override
        public void onSharedPreferenceChanged(SharedPreferences sp, String key) {
    // What do I do?  How do I make the wallpaper engine restart when settings are changed?  
        }

        private class GIFWallpaperEngine extends WallpaperService.Engine {

            private final int frameDuration = 20;

            private SurfaceHolder holder;
            private Movie movie;
            private boolean visible;
            private Handler handler;

            public GIFWallpaperEngine(Movie movie) {
                this.movie = movie;
                handler = new Handler();
            }

            @Override
            public void onCreate(SurfaceHolder surfaceHolder) {
                super.onCreate(surfaceHolder);
                this.holder = surfaceHolder;
            }

            private Runnable drawGIF = new Runnable() {
                public void run() {
                    draw();
                }
            };


            private void draw() {
                if (visible) {
                    Canvas canvas = holder.lockCanvas();
                    canvas.save();
                        // Adjust size and position so that
                        // the image looks good on your screen
                        canvas.scale(3f, 3f);
                        movie.draw(canvas, -100, 0);
                    canvas.restore();
                    holder.unlockCanvasAndPost(canvas);
                    movie.setTime((int) (System.currentTimeMillis() % movie.duration()));

                    handler.removeCallbacks(drawGIF);
                    handler.postDelayed(drawGIF, frameDuration);
                }
            }

            @Override
            public void onVisibilityChanged(boolean visible) {
                this.visible = visible;
                if (visible) {
                    handler.post(drawGIF);
                } else {
                    handler.removeCallbacks(drawGIF);
                }
            }

            @Override
            public void onDestroy() {
                super.onDestroy();
                handler.removeCallbacks(drawGIF);
            }
        }
    }

我可能迟到了，但希望有人会发现这很有用。

您需要首先指定并注册您的 SharedPrefs。将其添加到您的 onCreate() 方法中。

SharedPreferences preferences = getSharedPreferences("PREFERENCES NAME", Context.MODE_PRIVATE);
        preferences.registerOnSharedPreferenceChangeListener(this);