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android - 在 Android 上的 XML 布局文件中为 VideoView 设置 imageUrl

问题描述

我有一个从网站下载 JSON 输入的应用程序，该网站返回图片或视频的 URI。我没有问题让我的 MaterialCardView 通过 ImageView 显示图片。我的计划是设置一个覆盖 VideoView，仅当特定项目是视频类型时才可见。这是 2 个视图的 XML：

<ImageView
    android:id="@+id/picture_image"
    android:layout_width="377dp"
    android:layout_height="429dp"
    android:layout_marginBottom="84dp"
    android:adjustViewBounds="true"
    android:contentDescription="@string/nasa_pictures_list_id"
    android:padding="2dp"
    android:scaleType="centerCrop"

    app:imageUrl="@{picture.imgSrcUrl}"
    app:layout_constraintBottom_toTopOf="@+id/picture_title"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.47"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    tools:layout_conversion_absoluteHeight="191dp"
    tools:layout_conversion_absoluteWidth="411dp"
    tools:src="@tools:sample/backgrounds/scenic" />
    <!-- android:visibility="@{picture.image ? View.VISIBLE : View.GONE}"-->

<VideoView
    android:id="@+id/picture_video"
    android:layout_width="377dp"
    android:layout_height="429dp"
    android:layout_marginBottom="84dp"
    android:adjustViewBounds="true"
    android:contentDescription="@string/nasa_pictures_list_id"
    android:padding="2dp"
    android:scaleType="centerCrop"

    app:imageUrl="@{picture.imgSrcUrl}"
    app:layout_constraintBottom_toTopOf="@+id/picture_title"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.47"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    tools:layout_conversion_absoluteHeight="191dp"
    tools:layout_conversion_absoluteWidth="411dp"
    tools:src="@tools:sample/backgrounds/scenic" />
    <!-- android:visibility="@{picture.video ? View.VISIBLE : View.GONE}"-->

我现在注释掉了 android:visibility 代码。

我的问题是 VideoView 有一个编译错误，app:imageUrl="@{picture.imgSrcUrl}"它在前面的 ImageView 上工作得很好。错误是：

Cannot find a setter for <android.widget.VideoView app:imageUrl> that accepts parameter type 'java.lang.String'

好的，我明白了，它不喜欢字符串。

感谢页面

标签： androidandroid-layoutandroid-videoviewimageurl

解决方案

我得出的结论是，您不能通过 XML 文件执行此操作。我找不到一个这样做的例子。我所做的是修改我在SampleVideoView高级 Android 培训中找到的代码，该代码有效，可以在此处找到；https://github.com/google-developer-training/android-advanced/tree/master/SimpleVideoView

首先，我在我的应用程序中创建了一个 Java 类，如下所示：

public class VideoViewAdapter {

    private  String VIDEO_SAMPLE =
            "https://images.all-free-download.com/footage_preview/mp4/rocket_launch_cape_caneveral_nasa_535.mp4";


    private Context mContext;
    private VideoView mVideoView;


    // Current playback position (in milliseconds).
    private int mCurrentPosition = 0;

    // Tag for the instance state bundle.
    private static final String PLAYBACK_TIME = "play_time";

    public void initVideo(Context context, VideoView videoView) {
        // Set up the media controller widget and attach it to the video view.
        mVideoView = videoView;
        MediaController controller = new MediaController(context);
        controller.setMediaPlayer(mVideoView);
        mVideoView.setMediaController(controller);
        mContext = context;
    }

    public void initializePlayer(VideoView videoView,String url, int position) {

        if(url!=null) VIDEO_SAMPLE = url;
        if(position!=0) mCurrentPosition = position;
        mVideoView = videoView;
        // Buffer and decode the video sample.
        Uri videoUri = getMedia(VIDEO_SAMPLE);
        mVideoView.setVideoURI(videoUri);

        // Listener for onPrepared() event (runs after the media is prepared).
        mVideoView.setOnPreparedListener(
                new MediaPlayer.OnPreparedListener() {
                    @Override
                    public void onPrepared(MediaPlayer mediaPlayer) {

                        // Restore saved position, if available.
                        if (mCurrentPosition > 0) {
                            mVideoView.seekTo(mCurrentPosition);
                        } else {
                            // Skipping to 1 shows the first frame of the video.
                            mVideoView.seekTo(1);
                        }

                        // Start playing!
                        mVideoView.start();
                    }
                });

        // Listener for onCompletion() event (runs after media has finished
        // playing).
        mVideoView.setOnCompletionListener(
                new MediaPlayer.OnCompletionListener() {
                    @Override
                    public void onCompletion(MediaPlayer mediaPlayer) {
                        Toast.makeText(mContext,
                                R.string.toast_message,
                                Toast.LENGTH_SHORT).show();

                        // Return the video position to the start.
                        mVideoView.seekTo(0);
                    }
                });
    }


    // Release all media-related resources. In a more complicated app this
    // might involve unregistering listeners or releasing audio focus.
    public void releasePlayer() {
        mVideoView.stopPlayback();
    }

    // Get a Uri for the media sample regardless of whether that sample is
    // embedded in the app resources or available on the internet.
    private Uri getMedia(String mediaName) {
        if (URLUtil.isValidUrl(mediaName)) {
            // Media name is an external URL.
            return Uri.parse(mediaName);
        } else {
            // Media name is a raw resource embedded in the app.

            return Uri.parse("android.resource://" + mContext.getPackageName() +
                    "/raw/" + mediaName);
        }
    }
}

这为我提供了一个视图适配器，我可以像这样在 MainActivity 顶部实例化它：

现在在科特林：

.
.
.
lateinit var VIDEOADAPTOR: VideoViewAdapter
.
class MainActivity : AppCompatActivity() {



    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        .
        .
        .
        VIDEOADAPTOR = VideoViewAdapter()

然后在 Fragment 类文件中为布局片段。我将以下代码放在 onBindViewHolder 覆盖下的 RecyclerView.Adapter 类中。

class DailyPictureAdapter(val callback: PictureClick) : RecyclerView.Adapter<DailyPictureViewHolder>() {

.
.
.
/**
     * Called by RecyclerView to display the data at the specified position. This method should
     * update the contents of the {@link ViewHolder#itemView} to reflect the item at the given
     * position.
     */
    override fun onBindViewHolder(holder: DailyPictureViewHolder, position: Int) {
        holder.viewDataBinding.also {
            it.picture = pictures[position]
            it.pictureCallback = callback
            if(pictures[position].isVideo) {
                VIDEOADAPTOR.initVideo(context, it.pictureVideo)
                VIDEOADAPTOR.initializePlayer(it.pictureVideo,it.pictureVideo.pictures[position].imgSrcUrl, 0)

            }
        }
        holder.itemView.setOnClickListener{ callback.onClick(pictures[position])}

    }

}

作为 Recycler View 的一部分，它在 Video View 中播放了视频。不错但是....

我的问题是内存使用。对于我的应用程序，一次有 15 到 25 条记录，其中只有少数是视频，这不存在问题。但是，如果这是一个视频列表，我认为我们会很快发现内存问题。

当资源滚出视野时，我找不到释放资源的好地方。如果有人可以对此发表评论，请这样做。

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