[移动开发]项目实训—基于AI的智能视频剪辑器（七）创作历史页面

前言

用户在下载剪辑完毕的视频后，系统将会指定专门的文件夹对其进行存放。当用户进入创作历史页面后，就可以读取下载目录下的所有剪辑作品，由用户进行选择播放。由于之前视频播放器 VideoView 已经完成，这里的重点是利用 RecyclerView 实现一个播放列表。

VideoRecyclerViewAdapter

在使用 RecyclerView 这个强大的滚动控件的时候，需要为它提供一个 Adapter 适配器，这个适配器继承自 RecyclerView.Adapter 这个类。

这个类里面有三个抽象方法需要我们去重写，分别是：

这三个方法都是由安卓系统去调用的，其生命周期如下：

VideoHolder

创作历史页面的 RecyclerView 中的子 View 是 VideoView 对象，因此首先需要在 VideoRecyclerViewAdapter 创建内部类 VideoHolder 继承 ViewHolder

    public class VideoHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
        public int mPosition;
        public FrameLayout mPlayerContainer;
        public TextView mTitle;
        public ImageView mThumb;
        public PrepareView mPrepareView;

        VideoHolder(View itemView) {
            super(itemView);
            mPlayerContainer = itemView.findViewById(R.id.player_container);
            mTitle = itemView.findViewById(R.id.tv_title);
            mPrepareView = itemView.findViewById(R.id.prepare_view);
            mThumb = mPrepareView.findViewById(R.id.thumb);
            if (mOnItemChildClickListener != null) {
                mPlayerContainer.setOnClickListener(this);
            }
            if (mOnItemClickListener != null) {
                itemView.setOnClickListener(this);
            }
            //通过tag将ViewHolder和itemView绑定
            itemView.setTag(this);
        }

        @Override
        public void onClick(View v) {
            if (v.getId() == R.id.player_container) {
                if (mOnItemChildClickListener != null) {
                    mOnItemChildClickListener.onItemChildClick(mPosition);
                }
            } else {
                if (mOnItemClickListener != null) {
                    mOnItemClickListener.onItemClick(mPosition);
                }
            }

        }
    }

VideoRecyclerViewAdapter 实现需要重写的方法如下，为 RecyclerView 绑定了数据和布局：

    public VideoRecyclerViewAdapter(List<VideoBean> videos) {
        this.videos = videos;
    }

    @Override
    @NonNull
    public VideoHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_video, parent, false);
        return new VideoHolder(itemView);
    }

    @Override
    public void onBindViewHolder(@NonNull VideoHolder holder, int position) {
        VideoBean videoBean = videos.get(position);
        // 根据视频 url 获取封面图
        Glide.with(holder.mThumb.getContext()).setDefaultRequestOptions(
                new RequestOptions()
                        .frame(0)
                        .centerCrop()
                )
                .load(videoBean.getUrl())
                .placeholder(android.R.color.darker_gray)
                .into(holder.mThumb);
        holder.mTitle.setText(videoBean.getTitle());
        holder.mPosition = position;
    }

HistoryFragment

创作历史页面也是继承 BaseFragment ，在进入页面后，首先需要获取读写内存权限，而后获取项目下载路径下所有视频的 url

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        UrlList = new ArrayList<>();
        // 如果尚未获取到权限
        if (ContextCompat.checkSelfPermission(this.getContext(), Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED ||
                ContextCompat.checkSelfPermission(this.getContext(),Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED)
        {
            //申请权限
            ActivityCompat.requestPermissions(this.getActivity(),
                    new String[]{Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE}, 0);
        }
        else{
            getUrlList(AbsolutePath);
        }
    }

读写权限的 onRequestPermissionsResult

    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (requestCode == 0) {
            for (int i = 0; i < permissions.length; i++) {
                //选择“始终允许”
                if (grantResults[i] == PERMISSION_GRANTED) {
                    getUrlList(AbsolutePath);
                }
                else {
                    //选择了禁止不再询问
                    if (!ActivityCompat.shouldShowRequestPermissionRationale(this.getActivity(), permissions[i])){
                        AlertDialog.Builder builder = new AlertDialog.Builder(this.getContext());
                        builder.setTitle("permission")
                                .setMessage("点击允许才可以使用我们的app哦")
                                .setPositiveButton("去允许", new DialogInterface.OnClickListener() {
                                    public void onClick(DialogInterface dialog, int id) {
                                        if (mDialog != null && mDialog.isShowing()) {
                                            mDialog.dismiss();
                                        }
                                    }
                                });
                        mDialog = builder.create();
                        mDialog.setCanceledOnTouchOutside(false);
                        mDialog.show();
                    }
                    //选择禁止
                    else {
                        AlertDialog.Builder builder = new AlertDialog.Builder(this.getContext());
                        builder.setTitle("permission")
                                .setMessage("点击允许才可以使用我们的app哦")
                                .setPositiveButton("去允许", new DialogInterface.OnClickListener() {
                                    public void onClick(DialogInterface dialog, int id) {
                                        if (alertDialog != null && alertDialog.isShowing()) {
                                            alertDialog.dismiss();
                                        }
                                        ActivityCompat.requestPermissions(HistoryFragment.this.getActivity(),
                                                new String[]{Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE}, 0);
                                    }
                                });
                        alertDialog = builder.create();
                        alertDialog.setCanceledOnTouchOutside(false);
                        alertDialog.show();
                    }
                }
            }
        }
    }

获取路径下的所有视频 url

    public void getUrlList(String strPath) {
        File dir = new File(strPath);//文件夹dir
        File[] files = dir.listFiles();//文件夹下的所有文件或文件夹
        List<VideoBean> videoList = new ArrayList<>();
        if (files != null){
            for (int i = 0; i < files.length; i++) {
                PageLog.dTag(TAG,files[i].getAbsolutePath());
                UrlList.add(files[i].getAbsolutePath());//对于文件才把它的路径加到filelist中
                videoList.add(new VideoBean("预告片", files[i].getAbsolutePath()));
            }
        }
        mVideos.addAll(videoList);
    }

初始化页面，需要为视频播放器的页面设置监听以及Controller，并且为页面的RecycleView 绑定布局管理器与 VideoRecyclerViewAdapter

    @Override
    protected void initViews() {
        initVideoView();
        // 获取页面的 RecycleView
        mRecyclerView = binding.review;
        // 绑定布局管理器
        mLinearLayoutManager = new LinearLayoutManager(getContext());
        mRecyclerView.setLayoutManager(mLinearLayoutManager);
        // 设置 Adapter
        mAdapter = new VideoRecyclerViewAdapter(mVideos);
        mAdapter.setOnItemChildClickListener(this);
        mRecyclerView.setAdapter(mAdapter);
        mRecyclerView.addOnChildAttachStateChangeListener(new RecyclerView.OnChildAttachStateChangeListener() {
            @Override
            public void onChildViewAttachedToWindow(@NonNull View view) {
            }

            @Override
            public void onChildViewDetachedFromWindow(@NonNull View view) {
                FrameLayout playerContainer = view.findViewById(R.id.player_container);
                View v = playerContainer.getChildAt(0);
                if (v != null && v == mVideoView && !mVideoView.isFullScreen()) {
                    releaseVideoView();
                }
            }
        });
    }
    
    protected void initVideoView() {
        mVideoView = new VideoView(getActivity());
        mVideoView.setOnStateChangeListener(new VideoView.SimpleOnStateChangeListener() {
            @Override
            public void onPlayStateChanged(int playState) {
                //监听VideoViewManager释放，重置状态
                if (playState == VideoView.STATE_IDLE) {
                    PlayerUtils.removeViewFormParent(mVideoView);
                    mLastPos = mCurPos;
                    mCurPos = -1;
                }
            }
        });
        mController = new StandardVideoController(getActivity());
        mErrorView = new ErrorView(getActivity());
        mController.addControlComponent(mErrorView);
        mCompleteView = new CompleteView(getActivity());
        mController.addControlComponent(mCompleteView);
        mTitleView = new TitleView(getActivity());
        mController.addControlComponent(mTitleView);
        mController.addControlComponent(new VodControlView(getActivity()));
        mController.addControlComponent(new GestureView(getActivity()));
        mController.setEnableOrientation(true);
        mVideoView.setVideoController(mController);
    }

当点击播放页面的某个视频后，需要获取当前点击的播放器，找到绑定的VideoHolder，把列表中预置的PrepareView添加到控制器中，而后进行播放

    protected void startPlay(int position) {
        if (mCurPos == position) return;
        if (mCurPos != -1) {
            releaseVideoView();
        }
        VideoBean videoBean = mVideos.get(position);

        mVideoView.setUrl(videoBean.getUrl());
        mTitleView.setTitle(videoBean.getTitle());
        // 获取当前点击的播放器
        View itemView = mLinearLayoutManager.findViewByPosition(position);
        if (itemView == null) return;
        // 获取绑定的 viewHolder
        VideoRecyclerViewAdapter.VideoHolder viewHolder = (VideoRecyclerViewAdapter.VideoHolder) itemView.getTag();
        //把列表中预置的PrepareView添加到控制器中
        mController.addControlComponent(viewHolder.mPrepareView, true);
        PlayerUtils.removeViewFormParent(mVideoView);
        viewHolder.mPlayerContainer.addView(mVideoView, 0);
        mVideoView.start();
        mCurPos = position;
    }

释放当前播放的视频资源

    private void releaseVideoView() {
        mVideoView.release();
        if (mVideoView.isFullScreen()) {
            mVideoView.stopFullScreen();
        }
        if(getActivity().getRequestedOrientation() != ActivityInfo.SCREEN_ORIENTATION_PORTRAIT) {
            getActivity().setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
        }
        mCurPos = -1;
    }

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