Question

正如您所看到的，我有这个PlayLesson_01活动，它同时显示图像和音频。此活动有两个处理程序，一个用于控制图像和音频，另一个将完成课程并返回上一个活动（课程菜单）。

目标：点击“硬回”按钮返回上一个活动并停止播放图像和音频。

问题：当我点击“返回”时，我可以返回上一个活动，但音频仍在播放。我无法停止< / strong>或 kill 在活动中启动的处理程序。

问题：如何彻底杀死或停止这些处理程序？

import android.app.Activity; import android.content.Context; import android.content.Intent; import android.media.MediaPlayer; import android.media.MediaPlayer.OnCompletionListener; import android.os.Bundle; import android.os.Handler; import android.os.Looper; import android.view.View; import android.view.ViewGroup; import android.view.Window; import android.view.animation.AnimationUtils; import android.widget.AdapterView; import android.widget.AdapterView.OnItemSelectedListener; import android.widget.BaseAdapter; import android.widget.Gallery; import android.widget.ImageSwitcher; import android.widget.ImageView; import android.widget.RelativeLayout.LayoutParams; import android.widget.ViewSwitcher.ViewFactory; public class PlayLesson_01 extends Activity implements OnItemSelectedListener, ViewFactory, Runnable { // Setting up images // Keeping all Images in array references to our images public Integer[] mThumbIds = { R.drawable.nouraniyah, R.drawable.back_angle, R.drawable.back_fox, R.drawable.back_apple, R.drawable.back_twitter, R.drawable.back_thunderbird }; // setting up music int[] myMusic = { R.raw.button_3, R.raw.button_3, R.raw.button_3, R.raw.button_3, R.raw.button_3, R.raw.button_3 }; int mNext; private ImageSwitcher mSwitcher; MediaPlayer mp; Handler mHandlerWholeLesson = new Handler(); Runnable mRunnableWholelesson = new Runnable() { @Override public void run() { // TODO Auto-generated method stub startActivity(new Intent("com.example.AmazingGame.LESSONONE")); } }; Handler mHandlerNextfile = new Handler(); Runnable mRunnableNextFile = new Runnable() { @Override public void run() { // TODO Auto-generated method stub mp.setOnCompletionListener(mListener); mp.start(); } }; @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); requestWindowFeature(Window.FEATURE_NO_TITLE); setContentView(R.layout.image_switcher); // it could be lesson one // layout. mSwitcher = (ImageSwitcher) findViewById(R.id.imgswitcher); mSwitcher.setFactory(this); mSwitcher.setInAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_in)); mSwitcher.setOutAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_out)); Gallery g = (Gallery) findViewById(R.id.gallery); g.setAdapter(new ImageAdapter(this)); g.setOnItemSelectedListener(this); // usual onCreate stuff here, then... // either here or whenever you want to start the sequence mNext = 0; startNextFile(); // Is this good !! Yes it is. count the time for all audio. mHandlerWholeLesson.postDelayed(mRunnableWholelesson, 25000); } @Override public void onBackPressed() { super.onBackPressed(); startActivity(new Intent("com.example.AmazingGame.LESSONONE")); System.exit(0); mHandlerNextfile .removeCallbacks(mRunnableNextFile, PlayLesson_01.class); mHandlerWholeLesson.removeCallbacks(mRunnableWholelesson, PlayLesson_01.class); PlayLesson_01.this.finish(); } @Override protected void onDestroy() { // TODO Auto-generated method stub super.onDestroy(); // mHandlerNextFile.removeCallbacksAndMesssages(PlayLesson_01.class); } public void onItemSelected(AdapterView<?> parent, View v, final int position, long id) { } @Override public void onNothingSelected(AdapterView<?> arg0) { // TODO Auto-generated method stub } @Override public View makeView() { ImageView i = new ImageView(this); i.setBackgroundColor(0xFF000000); i.setScaleType(ImageView.ScaleType.FIT_CENTER); i.setLayoutParams(new ImageSwitcher.LayoutParams( LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT)); return i; } public class ImageAdapter extends BaseAdapter { public ImageAdapter(Context c) { mContext = c; } public int getCount() { return mThumbIds.length; } public Object getItem(int position) { return position; } public long getItemId(int position) { return position; } public View getView(int position, View convertView, ViewGroup parent) { ImageView i = new ImageView(mContext); i.setImageResource(mThumbIds[position]); i.setAdjustViewBounds(true); i.setLayoutParams(new Gallery.LayoutParams( LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT)); i.setBackgroundResource(R.drawable.picture_frame); return i; } private Context mContext; } OnCompletionListener mListener = new OnCompletionListener() { @Override public void onCompletion(MediaPlayer mp) { mp.release(); startNextFile(); } }; @Override protected void onPause() { // TODO Auto-generated method stub super.onPause(); this.finish(); } public void startNextFile() { if (mNext < myMusic.length) { mp = MediaPlayer.create(this, myMusic[mNext]); mSwitcher.setImageResource(mThumbIds[mNext++]); mHandlerNextfile.postDelayed(mRunnableNextFile, 3000); } } @Override public void run() { // TODO Auto-generated method stub }

}

Answer 1

现在代码中有一些错误的东西：

如果你想回到以前的活动，你不要使用startActivity重新启动它，因为android的默认行为是它维护了一堆先前的活动。在按下back时，它将默认返回上一个活动（除非您使用某些标志启动了子活动。）
为什么要在背面按下System.exit(0);？您只需致电finish()即可完成当前活动。
从处理程序中删除回调的最佳方法是使用null作为参数。您可以尝试以下代码：
```
mHandlerNextfile.removeCallbacksAndMessages(null);
mHandlerWholeLesson.removeCallbacksAndMessages(null);
```
因为这会删除所有回调。请查看此链接以了解详情：http://developer.android.com/reference/android/os/Handler.html#removeCallbacksAndMessages(java.lang.Object)

Answer 2

您的处理程序不是＆＃34;正在运行＆＃34;，您的媒体播放器是。只需在mp.stop()中拨打onBackPressed()。

此外，Arun George说的话。

onBackPressed杀死活动中的处理程序 - Android

2 个答案: