我正在创建一个视频播放器。我已经实现了 onPause 方法来在按下主页按钮时获取媒体播放器的最后位置，并且在 onResume 中我将该位置设置为媒体播放器并调用开始。我的问题是，当我在 SDK 25 上运行应用程序时，它运行完美，但在 SDK < 24 上，应用程序崩溃，在媒体播放器上出现空指针异常
在 onCreate 方法中使用了以下方法:
mMediaPlayer.setOnVideoSizeChangedListener(this);
try {
mMediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
mMediaPlayer.setDataSource(this, Uri.parse(path));
mMediaPlayer.setOnPreparedListener(this);
mMediaPlayer.setOnCompletionListener(this);
} catch (IllegalArgumentException e) {
e.printStackTrace();
} catch (SecurityException e) {
e.printStackTrace();
} catch (IllegalStateException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
MediaPlayerActivity 的 onPause:
@Override
protected void onPause() {
super.onPause();
position = mMediaPlayer.getCurrentPosition();
resumedActivity = true;
mMediaPlayer.pause();
if(servicerunning) {
startnotification();
}
}
关于恢复:
@Override
protected void onResume() {
super.onResume();
if(resumedActivity && !mMediaPlayer.isPlaying()) {
mMediaPlayer.prepareAsync();
mMediaPlayer.seekTo((int) position);
mMediaPlayer.start();
mPauseButton.setImageResource(R.drawable.ic_media_pause);
if(servicerunning){
videoService.removenotification();
}
}
}
@Override
public boolean onSurfaceTextureDestroyed(SurfaceTexture surfaceTexture) {
resetPlayer();
return false;
}
Android 的 list :
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.fahadali.playerproject">
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WAKE_LOCK"/>
<application
android:allowBackup="true"
android:hardwareAccelerated="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:largeHeap="true"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<service android:enabled="true" android:name=".MusicService" >
</service>
<service android:enabled="true" android:name=".VideoService" >
</service>
<receiver android:name=".AlarmReceiver"/>
<activity
android:name=".MainActivity"
android:configChanges="orientation|screenSize"
android:label="@string/app_name"
android:theme="@style/AppTheme.NoActionBar"
android:launchMode="standard"
>
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".FilesActivity"
android:label="@string/title_activity_files"
android:theme="@style/AppTheme.NoActionBar" />
<activity
android:name=".MediaPlayerActivity"
android:configChanges="orientation|screenSize|keyboardHidden"
android:label="@string/title_activity_media_player"
android:theme="@style/AppTheme.NoActionBar"
android:launchMode="singleTask">
android:screenOrientation="portrait">
</activity>
<activity
android:name=".PermissionsActivity"
android:label="@string/title_activity_permissions"
android:theme="@style/AppTheme.NoActionBar">
</activity>
</application>
</manifest>
日志:
02-01 18:34:36.465 17654-17654/com.example.fahadali.playerproject E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.fahadali.playerproject, PID: 17654
java.lang.RuntimeException: Unable to resume activity {com.example.fahadali.playerproject/com.example.fahadali.playerproject.MediaPlayerActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.media.MediaPlayer.isPlaying()' on a null object reference
at android.app.ActivityThread.performResumeActivity(ActivityThread.java:3194)
at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:3225)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1506)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:160)
at android.app.ActivityThread.main(ActivityThread.java:5541)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:964)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:759)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.media.MediaPlayer.isPlaying()' on a null object reference
at com.example.fahadali.playerproject.MediaPlayerActivity.onResume(MediaPlayerActivity.java:1348)
at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1257)
at android.app.Activity.performResume(Activity.java:6179)
at android.app.ActivityThread.performResumeActivity(ActivityThread.java:3183)
at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:3225)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1506)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:160)
at android.app.ActivityThread.main(ActivityThread.java:5541)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:964)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:759)
我找不到任何解决方案。接下来我可以尝试什么？
最佳答案
您可以使用 pause 方法暂停媒体播放器，并记住您暂停媒体播放器的最后位置，如下所示:
Mediaplayer.pause();
length=Mediaplayer.getCurrentPosition();
然后你可以使用这个从你离开的位置恢复播放器:
Mediaplayer.seekTo(length);
Mediaplayer.start();
关于android - 从 onResume 的最后位置恢复 MediaPlayer，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/48563617/