我开发了使用viewpager的简单android imageview，它在后台播放音乐。它还会在到达最后一张图像时停止播放音乐，并在用户滑回图像时恢复音乐。但是，我的主要问题是当设备进入睡眠状态时音乐停止并且当设备再次启动而不是再次恢复音乐并显示图像时...强制关闭...有关如何解决此问题的任何建议...以下是我的代码...
Mainactivity.java
import android.app.Activity;
import android.content.Intent;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ShareActionProvider;
public class MainActivity extends Activity {
MediaPlayer oursong;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
oursong = MediaPlayer.create(MainActivity.this, R.raw.a);
oursong.seekTo(0);
oursong.start();
ViewPager viewPager = (ViewPager) findViewById(R.id.view_pager);
final ImageAdapter adapter = new ImageAdapter(this);
viewPager.setAdapter(adapter);
viewPager.setOnPageChangeListener(new OnPageChangeListener() {
@Override
public void onPageSelected(int pos) {
if (pos == adapter.getCount() - 1)
{
oursong.pause();
} else if (!oursong.isPlaying())
{
oursong.start();
}
}
@Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
// TODO Auto-generated method stub
}
@Override
public void onPageScrollStateChanged(int arg0) {
// TODO Auto-generated method stub
}
});
}
private ShareActionProvider mShareActionProvider;
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate menu resource file.
getMenuInflater().inflate(R.menu.activity_main, menu);
// Locate MenuItem with ShareActionProvider
MenuItem item = menu.findItem(R.id.menu_item_share);
// Fetch and store ShareActionProvider
mShareActionProvider = (ShareActionProvider) item.getActionProvider();
// Return true to display menu
return true;
}
// Call to update the share intent
private void setShareIntent(Intent shareIntent) {
if (mShareActionProvider != null) {
mShareActionProvider.setShareIntent(shareIntent);
}
}
@Override
protected void onPause() {
super.onPause();
oursong.release();
}
}
ImageAdapter.java
import java.io.IOException;
import android.app.WallpaperManager;
import android.content.Context;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
public class ImageAdapter extends PagerAdapter {
Context context;
private final int[] GalImages = new int[] {
R.drawable.one,
R.drawable.two,
R.drawable.three
};
ImageAdapter(Context context){
this.context=context;
}
@Override
public int getCount() {
return GalImages.length;
}
@Override
public boolean isViewFromObject(View view, Object object) {
return view == ((ImageView) object);
}
@Override
public Object instantiateItem(ViewGroup container, final int position) {
ImageView imageView = new ImageView(context);
int padding = context.getResources().getDimensionPixelSize(R.dimen.padding_small);
imageView.setPadding(padding, padding, padding, padding);
imageView.setScaleType(ImageView.ScaleType.FIT_XY);
imageView.setImageResource(GalImages[position]);
imageView.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
WallpaperManager myWallpaperManager = WallpaperManager.getInstance(context);
try {
myWallpaperManager.setResource(GalImages[position]);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
});
((ViewPager) container).addView(imageView, 0);
return imageView;
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
((ViewPager) container).removeView((ImageView) object);
}
}
Logcat错误....（在应用程序在实际设备上运行时采用了Logcat）
08-29 02:48:21.051: I/dalvikvm(2880): Could not find method android.widget.ShareActionProvider.setShareIntent, referenced from method com.manishkpr.viewpagerimagegallery.MainActivity.setShareIntent
08-29 02:48:21.051: W/dalvikvm(2880): VFY: unable to resolve virtual method 3259: Landroid/widget/ShareActionProvider;.setShareIntent (Landroid/content/Intent;)V
08-29 02:48:21.051: D/dalvikvm(2880): VFY: replacing opcode 0x6e at 0x0006
08-29 02:48:21.066: I/dalvikvm(2880): Could not find method android.view.MenuItem.getActionProvider, referenced from method com.manishkpr.viewpagerimagegallery.MainActivity.onCreateOptionsMenu
08-29 02:48:21.066: W/dalvikvm(2880): VFY: unable to resolve interface method 2912: Landroid/view/MenuItem;.getActionProvider ()Landroid/view/ActionProvider;
08-29 02:48:21.066: D/dalvikvm(2880): VFY: replacing opcode 0x72 at 0x0010
08-29 02:48:21.066: D/dalvikvm(2880): VFY: dead code 0x0013-0019 in Lcom/manishkpr/viewpagerimagegallery/MainActivity;.onCreateOptionsMenu (Landroid/view/Menu;)Z
08-29 02:48:21.230: W/MediaPlayer-cpp(2880): info/warning (802, 0)
08-29 02:48:21.348: I/MediaPlayer(2880): Info (802,0)
08-29 02:48:21.434: D/dalvikvm(2880): GC_EXTERNAL_ALLOC freed 1117 objects / 212256 bytes in 71ms
08-29 02:48:36.644: D/dalvikvm(2880): GC_EXTERNAL_ALLOC freed 553 objects / 29584 bytes in 32ms
08-29 02:50:00.566: D/AndroidRuntime(2880): Shutting down VM
08-29 02:50:00.566: W/dalvikvm(2880): threadid=1: thread exiting with uncaught exception (group=0x4001d8a8)
08-29 02:50:00.605: E/AndroidRuntime(2880): FATAL EXCEPTION: main
08-29 02:50:00.605: E/AndroidRuntime(2880): java.lang.RuntimeException: Unable to resume activity {com.manishkpr.viewpagerimagegallery/com.manishkpr.viewpagerimagegallery.MainActivity}: java.lang.IllegalStateException
08-29 02:50:00.605: E/AndroidRuntime(2880): at android.app.ActivityThread.performResumeActivity(ActivityThread.java:3128)
08-29 02:50:00.605: E/AndroidRuntime(2880): at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:3143)
08-29 02:50:00.605: E/AndroidRuntime(2880): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2059)
08-29 02:50:00.605: E/AndroidRuntime(2880): at android.os.Handler.dispatchMessage(Handler.java:99)
08-29 02:50:00.605: E/AndroidRuntime(2880): at android.os.Looper.loop(Looper.java:123)
08-29 02:50:00.605: E/AndroidRuntime(2880): at android.app.ActivityThread.main(ActivityThread.java:4627)
08-29 02:50:00.605: E/AndroidRuntime(2880): at java.lang.reflect.Method.invokeNative(Native Method)
08-29 02:50:00.605: E/AndroidRuntime(2880): at java.lang.reflect.Method.invoke(Method.java:521)
08-29 02:50:00.605: E/AndroidRuntime(2880): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
08-29 02:50:00.605: E/AndroidRuntime(2880): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
08-29 02:50:00.605: E/AndroidRuntime(2880): at dalvik.system.NativeStart.main(Native Method)
08-29 02:50:00.605: E/AndroidRuntime(2880): Caused by: java.lang.IllegalStateException
08-29 02:50:00.605: E/AndroidRuntime(2880): at android.media.MediaPlayer.seekTo(Native Method)
08-29 02:50:00.605: E/AndroidRuntime(2880): at com.manishkpr.viewpagerimagegallery.MainActivity.onResume(MainActivity.java:86)
08-29 02:50:00.605: E/AndroidRuntime(2880): at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1149)
08-29 02:50:00.605: E/AndroidRuntime(2880): at android.app.Activity.performResume(Activity.java:3823)
08-29 02:50:00.605: E/AndroidRuntime(2880): at android.app.ActivityThread.performResumeActivity(ActivityThread.java:3118)
08-29 02:50:00.605: E/AndroidRuntime(2880): ... 10 more
08-29 02:50:10.371: I/Process(2880): Sending signal. PID: 2880 SIG: 9
答案 0 :(得分：0)
您是否尝试将音乐播放移动到onResume（）活动生命周期中，片段不会再次调用onCreate（），直到您重新创建活动为止。因此，无需关闭您的应用即可恢复播放。
像这样的东西
import android.app.Activity;
import android.content.Intent;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ShareActionProvider;
public class MainActivity extends Activity {
MediaPlayer oursong;
ViewPager viewPager;
ImageAdapter adapter;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
oursong = MediaPlayer.create(MainActivity.this, R.raw.a);
oursong.seekTo(0);
oursong.start();
viewPager = (ViewPager) findViewById(R.id.view_pager);
adapter = new ImageAdapter(this);
viewPager.setAdapter(adapter);
viewPager.setOnPageChangeListener(MyViewPagerListener);
}
private ShareActionProvider mShareActionProvider;
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate menu resource file.
getMenuInflater().inflate(R.menu.activity_main, menu);
// Locate MenuItem with ShareActionProvider
MenuItem item = menu.findItem(R.id.menu_item_share);
// Fetch and store ShareActionProvider
mShareActionProvider = (ShareActionProvider) item.getActionProvider();
// Return true to display menu
return true;
}
// Call to update the share intent
private void setShareIntent(Intent shareIntent) {
if (mShareActionProvider != null) {
mShareActionProvider.setShareIntent(shareIntent);
}
}
@Override
protected void onPause() {
super.onPause();
if(oursong != null){
oursong.release();
}
}
@Override
protected void onResume(){
super.onResume();
/*
* This is the important part, basically since your releasing the song
* in onPause() you are getting rid of its reference, in this case check
* if your song is null then if it is re-create it, else you can reuse the
* the original, but i suspect that calling release() in onPause() allows the
* song to get cleaned up by Java's Garbage Collector.
*/
if(oursong == null){
oursong = MediaPlayer.create(MainActivity.this, R.raw.a);
oursong.seekTo(0); // You will probably want to save an int to restore here
oursong.start();
}else{
oursong.seekTo();
oursong.start();
}
}
/*
* May want to add two methods here: onSaveInstanceState(Bundle outstate) &
* onRestoreInstanceState(Bundle savedInstanceState) to maintain playback position
* in onResume instead of just restarting the song.
*/
private final OnPageChangeListener MyViewPagerListener = new OnPageChangeListener() {
@Override
public void onPageSelected(int pos) {
if (pos == adapter.getCount() - 1){
// adding null checks for safety
if(oursong != null){
oursong.pause();
}
} else if (!oursong.isPlaying()){
// adding null check for safety
if(oursong != null){
oursong.start();
}
}
}
@Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
// TODO Auto-generated method stub
}
@Override
public void onPageScrollStateChanged(int arg0) {
// TODO Auto-generated method stub
}
};
}
希望这有助于您解决问题。