安卓之播放本地视频讲解

第一种形式：（网络的URL）

Intent it = new Intent();
it.setAction(Intent.ACTION_VIEW);
it.setData(Uri.parse("http://www.baidu.com"));
startActivity(it);

第二种形式：（本地URL）

Intent intent = new Intent(Intent.ACTION_VIEW);
Uri uri = Uri.parse("file:///sdcard/foo.mp3");
intent.setDataAndType(uri, "audio/mp3");
startActivity(intent);

可是有时候我们加载本地URL的形式却是这样子的：/storage/emulated/0/video/test.MP4
如果还是用Uri.parse()可能在一些手机调用不到系统的播放器（播放不了），解决办法如下：
把Uri.parse()改为Uri.fromFile(new File(URL));

有一种需求是获取本地视频的缩略图，网上有很多办法获取，在这里我只介绍一种，本人觉得是最有用，最有效的：（异步，缓存加载）
这里有个工具类：

/**
 * Created by CWJ on 2016/4/15.
 */
public class VideoThumbnailLoader {
    private static VideoThumbnailLoader mInstance;
    private Map<String, SoftReference<Bitmap>> caches;

    private List<LoadTask> mTaskQueue;

    public static VideoThumbnailLoader getInstance(){
        if (mInstance == null){
            mInstance = new VideoThumbnailLoader();
        }
        return mInstance;
    }
    private VideoThumbnailLoader(){
        caches = new HashMap<>();
        mTaskQueue = new ArrayList<>();
        isRunning = true;
        runnable = new LoadRunnable();
        new Thread(runnable).start();
    }

    public void displayThumbnail(ImageView imageView, String videoPath, int resId) {
        imageView.setTag(videoPath);
        Bitmap bitmap = loadImage(videoPath, getImageCallback(imageView, resId));

        if (bitmap == null){
            imageView.setImageResource(resId);
        }else {
            imageView.setImageBitmap(bitmap);
        }
    }

    private Bitmap loadImage(String videoPath, ImageCallback callback) {
        if (caches .containsKey(videoPath)){
            SoftReference<Bitmap> softReference = caches.get(videoPath);
            Bitmap bitmap = softReference.get();
            if (bitmap == null){
                caches.remove(videoPath);
            }else {
                return bitmap;
            }
        }else {
            LoadTask task = new LoadTask();
            task.path = videoPath;
            task.callback = callback;
            if (!mTaskQueue.contains(task)){
                mTaskQueue.add(task);
                synchronized (runnable) {
                    runnable.notify();
                }
            }
        }
        return null;
    }

    //回调接口
    public interface ImageCallback{
        void loadImage(String path, Bitmap bitmap);
    }

    class LoadTask{
        String path;
        Bitmap bitmap;
        ImageCallback callback;

        @Override
        public boolean equals(Object o) {
            LoadTask task = (LoadTask)o;
            return task.path.equals(path);
        }
    }

    private LoadRunnable runnable;
    private boolean isRunning = false;
    class LoadRunnable implements Runnable {
        @Override
        public void run() {
            while (isRunning){
                while (mTaskQueue.size() > 0){
                    LoadTask task = mTaskQueue.remove(0);
                    task.bitmap = CustomUtil.getVideoThumbnail1(task.path);
                    caches.put(task.path, new SoftReference<Bitmap>(task.bitmap));
                    if(handler != null){
                        Message msg = handler.obtainMessage();
                        msg.obj = task;
                        handler.sendMessage(msg);
                    }
                }

                synchronized (this) {
                    try {
                        this.wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }
    }

    private ImageCallback getImageCallback(final ImageView imageView, final int resId){
        return new ImageCallback() {
            @Override
            public void loadImage(String path, Bitmap bitmap) {
                if(path.equals(imageView.getTag().toString())){
                    imageView.setImageBitmap(bitmap);
                }else{
                    imageView.setImageResource(resId);
                }
            }
        };
    }

    private Handler handler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
            LoadTask task = (LoadTask)msg.obj;
            task.callback.loadImage(task.path, task.bitmap);
        }

    };
}

然后在listview或者recycleview加载item：

VideoThumbnailLoader.getInstance().displayThumbnail(holder.iv_photo, sdState + array.get(position - 1), R.drawable.loading_img);

第一个参数的加载的view（ImageView），第二个是文件的路径（URL），第三个是默认加载的图片，也就是当没有获取到视频缩略图时默认显示的图片。