最近做的项目，客户临时要求改版，我真的是最烦这个，要求跟换主页面的背景，换上新的背景图，要求是动态的。

效果（我随便拿的五个图片做的gif）：

方案:

帧动画方案:

        缺点:1.好像只能imageview才能播放帧动画 

                2.容易OOM（播三四张还行，播九十张以上，且，每张都在300k左右就有OOM问题）

                3.看到网上方案解决帧动画OOM，是一次播放十张，再往里面添十张，再播放。问题就有了，动画有一个                      添加十个图片的时间卡顿。

surfaceview方案:

         因为imageview要是以一张一张换，性能必定不如surfaceview。核心应该是

      canvas = surfaceHolder.lockCanvas(rect);
      canvas.drawBitmap(lruCache.get(folderName + "/" + assets[position]), null, rect, null);

        surfaceHolder = sv_main.getHolder();
        lruCache = new StringBitmapLruCache();
        surfaceHolder.addCallback(new SurfaceHolder.Callback() {
            @Override
            public void surfaceCreated(SurfaceHolder holder) {

            }

            @Override
            public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {


                rect = new Rect(0, 0, width, height);

                //获取主题
                SharedPreferences sp = getSharedPreferences("setting", Context.MODE_PRIVATE);
                String theme = sp.getString("theme", "bgone");
                switch (theme) {
                    case "bgone":
                        folderName = "bgone";
                        break;
                    case "bgtwo":
                        folderName = "bgtwo";
                        break;
                    case "bgthree":
                        folderName = "bgthree";
                        break;
                }

                try {
                    assetManager = getAssets();
                    assets = assetManager.list(folderName);
                    totalCount = assets.length;
                    if (lruCache.get(folderName + "/" + assets[0]) == null) {
                        Bitmap bitmap = BitmapFactory.decodeStream(assetManager.open(folderName + "/" + assets[0]));
                        lruCache.put(folderName + "/" + assets[0], bitmap);
                    }
                    canvas = surfaceHolder.lockCanvas(rect);
                    canvas.drawBitmap(lruCache.get(folderName + "/" + assets[0]), null, rect, null);
                    holder.unlockCanvasAndPost(canvas);

                    if (!isFlag) {
                        startDecodeThread();
                        isFlag = true;
                    }


                } catch (IOException e) {
                    e.printStackTrace();
                }

                isFlag = true;


            }

            @Override
            public void surfaceDestroyed(SurfaceHolder holder) {
                RxUtils.unsubscribe(animationSub);
            }
        });

 private void startDecodeThread() {

        RxUtils.unsubscribe(animationSub);
        animationSub = Observable.interval(200, TimeUnit.MILLISECONDS).subscribeOn(Schedulers.io()).subscribe(new Subscriber<Long>() {
            @Override
            public void onCompleted() {

            }

            @Override
            public void onError(Throwable e) {

            }

            @Override
            public void onNext(Long aLong) {
                Logger.i("DDSSK::" + position);
                if (position >= totalCount) {
                    position = 0;
                }

                canvas = surfaceHolder.lockCanvas(rect);
                // if (canvas != null) {

                canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR);
                if (lruCache.get(folderName + "/" + assets[position]) == null) {
                    try {
                        Bitmap bitmap = BitmapFactory.decodeStream(assetManager.open(folderName + "/" + assets[position]));
                        lruCache.put(folderName + "/" + assets[position], bitmap);
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
                canvas.drawBitmap(lruCache.get(folderName + "/" + assets[position]), null, rect, null);
                surfaceHolder.unlockCanvasAndPost(canvas);


              /*  try {
                    Bitmap bitmap = BitmapFactory.decodeStream(assetManager.open(folderName + "/" + assets[0]));
                    canvas.drawBitmap(bitmap, null, rect, null);
                    surfaceHolder.unlockCanvasAndPost(canvas);

                } catch (IOException e) {
                    e.printStackTrace();
                }*/

                position++;
            }
        });
    }

1.surfaceview准备的时候，界面是一片黑。所以在surfacechanged的时候我要展示动画的第一张图，这样就不黑了

2.canvas为空？因为canvas是从surfaceview获得的，如果surfaceview没有准备好，它绝对为空

3.如果界面跳转再返回，surfaceview还会创建，但是我点了黑屏再亮屏，surfaceview就不会在创建，动画就播不了，所以要写一个开关，在onresume里写代码触发动画

4.surfaceview的优化，因为播放太多的图片，占用太多资源，导致其他的组件超卡。因为surfaceview可以在子线程跟新UI,所以我们可以起线程轮播图

附件:

package utils;

import android.graphics.Bitmap;
import android.support.v4.util.LruCache;

/**
 * Created by Administrator on 2017/6/23 0023.
 */

public class StringBitmapLruCache extends LruCache<String, Bitmap> {
    public StringBitmapLruCache() {
        // 构造方法传入当前应用可用最大内存的八分之一
        super((int) (Runtime.getRuntime().maxMemory() / 1024 / 8));
    }

    @Override
    // 重写sizeOf方法，并计算返回每个Bitmap对象占用的内存
    protected int sizeOf(String key, Bitmap value) {
        return value.getByteCount() / 1024;
    }

    @Override
    // 当缓存被移除时调用，第一个参数是表明缓存移除的原因，true表示被LruCache移除，false表示被主动remove移除，可不重写
    protected void entryRemoved(boolean evicted, String key, Bitmap oldValue, Bitmap
            newValue) {
        super.entryRemoved(evicted, key, oldValue, newValue);
    }

    @Override
    // 当get方法获取不到缓存的时候调用，如果需要创建自定义默认缓存，可以在这里添加逻辑，可不重写
    protected Bitmap create(String key) {
        return super.create(key);
    }
}