我正在开发一个应用，其中的功能之一是具有两个按钮，当这些按钮被触摸时，它们将在第二台显示器上全屏显示两个本地存储的视频之一。由于我使用的平板电脑具有HDMI输出端口，因此显示器直接通过HDMI电缆连接。无需通过搜索或停止来控制视频播放。再次按下该按钮，视频可以简单地重新开始（搜索为0）。如果用户正在播放video1并按下video2按钮，则假定video1将立即停止并且video2将开始。
当前的实现（下面包含一个存根）基本上可以按预期工作。当我第一次连接辅助显示器时，启动应用程序并按任一按钮，关联的视频开始在VideoView中播放。如果我再次单击该按钮或单击另一个按钮，则关联的视频将从头开始播放。
我遇到的错误发生在以下时间：我使用“后退”按钮退出应用程序，或者使用“概述”按钮使应用程序后台运行，或者通过向内滑动应用程序退出应用程序应用概述。下次我打开该应用程序并单击一个视频按钮时，辅助显示器上什么也没有发生。它只是作为平板电脑主显示屏的一面镜子。如果我拆下并重新连接辅助显示器，即使在应用程序打开的情况下，按钮也会按预期开始工作。这使我相信，在应用程序暂停或停止时，我没有正确清理Presentation，MediaRouter或VideoView。任何帮助将不胜感激。如果添加主要活动代码有帮助，请告诉我。
import android.content.res.Resources;
import android.media.MediaPlayer;
import android.media.MediaRouter;
import android.content.Context;
import android.app.Presentation;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.text.method.ScrollingMovementMethod;
import android.view.Display;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.MotionEvent;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.VideoView;
import android.util.Log;
import java.util.ArrayList;
import java.util.Map;
public class GuiFragment extends Fragment{
private MediaRouter mMediaRouter;
private VideoPresentation mPresentation;
public GuiFragment() {
// Required empty public constructor
}
@Override
public void onCreate(Bundle savedInstanceState) {
Log.e("GuiFragment", "onCreate");
super.onCreate(savedInstanceState);
// Get the media router service.
mMediaRouter = (MediaRouter) getActivity().getSystemService(Context.MEDIA_ROUTER_SERVICE);
}
@Override
public void onPause() {
Log.e("GuiFragment", "onPause");
// Be sure to call the super class.
super.onPause();
// Dismiss the presentation when the activity is not visible.
stopVideo();
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
Log.e("GuiFragment", "onCreateView");
View rootView = inflater.inflate(R.layout.fragment_connection_gui, container, false);
// Initialize Button objects
Button video1Button = (Button) rootView.findViewById(R.id.vid1_button);
Button video2Button = (Button) rootView.findViewById(R.id.vid2_button);
video1Button.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
switch(event.getAction()) {
case MotionEvent.ACTION_UP:
Log.e("GuiFragment", "video1 button event");
int duration = Toast.LENGTH_SHORT;
MediaRouter.RouteInfo route = mMediaRouter.getSelectedRoute(MediaRouter.ROUTE_TYPE_LIVE_VIDEO);
if (route != null) {
Log.e("GuiFragment", "Obtained Video Media Route");
Display presentationDisplay = route.getPresentationDisplay();
if (presentationDisplay != null) {
Log.e("GuiFragment", "Obtained Presentation Display, Presenting Video");
//if (mPresentation == null)
//{
Log.e("GuiFragment", "Video1: No presentation, create a new one");
mPresentation = new VideoPresentation(getActivity(), presentationDisplay,
Uri.parse("android.resource://" + getActivity().getPackageName() + "/" + R.raw.bigbuckbunny));
mPresentation.show();
//}
//else
//{
// Log.e("GuiFragment", "Video1: Presentation exists, update URI");
// mPresentation.stopVideoView();
// mPresentation.updateVideo(Uri.parse("android.resource://" + getActivity().getPackageName() + "/" + R.raw.bigbuckbunny));
//}
}
else {
Toast toast = Toast.makeText(getActivity(), "No Display", duration);
toast.show();
}
}
else {
Toast toast = Toast.makeText(getActivity(), "No MediaRouter", duration);
toast.show();
}
break;
default:
break;
}
/* This causes onClick not to be called. You would need it for accessibility options
but we don't really care about that in this app */
return true;
}
});
video2Button.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
switch(event.getAction()) {
case MotionEvent.ACTION_UP:
Log.e("GuiFragment", "video2 button event");
int duration = Toast.LENGTH_SHORT;
MediaRouter.RouteInfo route = mMediaRouter.getSelectedRoute(MediaRouter.ROUTE_TYPE_LIVE_VIDEO);
if (route != null) {
Log.e("GuiFragment", "Obtained Video Media Route");
Display presentationDisplay = route.getPresentationDisplay();
if (presentationDisplay != null) {
Log.e("GuiFragment", "Obtained Presentation Display, Presenting Video");
//if (mPresentation == null)
//{
Log.e("GuiFragment", "Video2: No presentation, create a new one");
mPresentation = new VideoPresentation(getActivity(), presentationDisplay,
Uri.parse("android.resource://" + getActivity().getPackageName() + "/" + R.raw.bigbuckbunny));
mPresentation.show();
//}
//else
//{
// Log.e("GuiFragment", "Video2: Presentation exists, update URI");
// mPresentation.stopVideoView();
// mPresentation.updateVideo(Uri.parse("android.resource://" + getActivity().getPackageName() + "/" + R.raw.bigbuckbunny));
//}
}
else {
Toast toast = Toast.makeText(getActivity(), "No Display", duration);
toast.show();
}
}
else {
Toast toast = Toast.makeText(getActivity(), "No MediaRouter", duration);
toast.show();
}
break;
default:
break;
}
/* This causes onClick not to be called. You would need it for accessibility options
but we don't really care about that in this app */
return true;
}
});
// Inflate the layout for this fragment
return rootView;
}
private void stopVideo() {
Log.e("GuiFragment", "stopVideo()");
if (mPresentation != null) {
Log.e("GuiFragment", "Stopping video1 playback");
mPresentation.stopVideoView();
mPresentation.dismiss();
mPresentation = null;
}
}
private final static class VideoPresentation extends Presentation {
VideoView mVideoView;
Context mContext;
Uri mVideo;
public VideoPresentation(Context context, Display display, Uri video) {
super(context, display);
mContext = context;
mVideo = video;
}
@Override
protected void onCreate(Bundle savedInstanceState) {
Log.e("VideoPresentation", "onCreate");
// Be sure to call the super class.
super.onCreate(savedInstanceState);
// Get the resources for the context of the presentation.
// Notice that we are getting the resources from the context of the presentation.
Resources r = getContext().getResources();
// Inflate the layout.
setContentView(R.layout.presentation_with_media_router_activity);
mVideoView = (VideoView) findViewById(R.id.video_view);
mVideoView.requestFocus();
mVideoView.setVideoURI(mVideo);
mVideoView.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
public void onPrepared(MediaPlayer mediaPlayer) {
mVideoView.start();
}
});
}
@Override
protected void onStart() {
Log.e("VideoPresentation", "onStart");
// Be sure to call the super class.
super.onStart();
}
@Override
protected void onStop() {
Log.e("VideoPresentation", "onStop");
// Be sure to call the super class.
super.onStop();
}
@Override
public void onDetachedFromWindow() {
Log.e("VideoPresentation", "onDetachedFromWindow");
// Be sure to call the super class.
super.onDetachedFromWindow();
}
public void stopVideoView() {
mVideoView.stopPlayback();
}
public void updateVideo(Uri video) {
mVideo = video;
mVideoView.requestFocus();
mVideoView.setVideoURI(mVideo);
}
public VideoView getVideoView() {
return mVideoView;
}
}
}