问题描述
|
我试图弄清楚在媒体播放器准备流式文件时如何显示“正在加载。请稍候...”的进度条。现在发生的是在歌曲准备好之后显示。我怎样才能解决这个问题?
mediaPlayerLoadingBar =ProgressDialog.show(PlaylistActivity.this,\"\",\"Loading. Please wait...\",true);
/*dubstep stream*/
try {
dubstepMediaPlayer.setDataSource(dubstepPlaylistString[0]);
dubstepMediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
dubstepMediaPlayer.prepare();
} catch (IllegalArgumentException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SecurityException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalStateException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
dubstepMediaPlayer.start();
if(dubstepMediaPlayer.isPlaying()){
mediaPlayerLoadingBar.dismiss();
}`
编辑:
这是我现在拥有的代码:
`switch(pSelection){
情况1:
new AsyncTask<Void,Void,Void>(){
@Override
protected void onPreExecute(){
mediaPlayerLoadingBar =ProgressDialog.show(PlaylistActivity.this,true);
try {
dubstepMediaPlayer.setDataSource(dubstepPlaylistString[0]);
} catch (IllegalArgumentException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalStateException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
dubstepMediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
}
@Override
protected Void doInBackground(Void... params) {
// TODO Auto-generated method stub
//mediaPlayerLoadingBar =ProgressDialog.show(PlaylistActivity.this,true);
return null;
}
protected void onPostExecute(Void result){
//mediaPlayerLoadingBar =ProgressDialog.show(PlaylistActivity.this,true)
dubstepMediaPlayer.prepareAsync();
dubstepMediaPlayer.start();
mediaPlayerLoadingBar.dismiss();
}
}.execute();`
解决方法
问题在于您没有在此处异步执行任何操作,应该这样做。您应该使用AsyncTask来完成工作。
看一下“ 4个步骤”,如下所示:
4个步骤
当执行异步任务时,该任务将经历4个步骤:
onPreExecute(),在执行任务后立即在UI线程上调用。此步骤通常用于设置任务,例如,通过在用户界面中显示进度栏。
doInBackground(Params ...),在onPreExecute()完成执行后立即在后台线程上调用。此步骤用于执行可能需要很长时间的后台计算。异步任务的参数将传递到此步骤。计算结果必须通过此步骤返回,并将传递回最后一步。此步骤还可以使用publishProgress(Progress ...)发布一个或多个进度单位。这些值在onProgressUpdate(Progress ...)步骤中发布在UI线程上。
onProgressUpdate(Progress ...),在调用publishProgress(Progress ...)之后在UI线程上调用。执行的时间是不确定的。此方法用于在后台计算仍在执行时在用户界面中显示任何形式的进度。例如,它可用于为进度栏设置动画或在文本字段中显示日志。
onPostExecute(Result),在后台计算完成后在UI线程上调用。后台计算的结果作为参数传递到此步骤。
编辑:
您可以创建一个匿名内部类来进行出价,这可能类似于创建onClick处理程序的方式。在您的onClick中执行以下操作:
//pseudo-code...
onClick(View v,...) {
new AsyncTask<Generic1,Generic2,Generic3>() {
protected void onPreExecute() {
// do pre execute stuff...
}
protected Generic3 doInBackground(Generic1... params) {
// do background stuff...
}
protected void onPostExecute(Generic3 result) {
// do post execute stuff...
}
}.execute();
}
不要忘记在这里关注您的仿制药!
, 如果有人仍然面临这个问题,下面的代码
AsyncTask<Void,Void,Void> task = new AsyncTask<Void,Void>() {
@Override
protected void onPreExecute() {
if(translation.equals(\"NIV\"))
{
if(AudioPlaying==false)
{
mediaPlayer = new MediaPlayer();
mediaPlayer.setOnPreparedListener(Main.this);
mediaController = new MediaController(Main.this);
}
else
mediaController.show();
}
else
Toast.makeText(getBaseContext(),\"عفوا,جاري تحميل ملفات الصوت الخاصة بترجمة الفانديك \",Toast.LENGTH_LONG).show();
pd = new ProgressDialog(Main.this);
pd.setTitle(\"Processing...\");
pd.setMessage(\"Please wait.\");
pd.setCancelable(false);
pd.setIndeterminate(true);
pd.show();
}
@Override
protected Void doInBackground(Void... arg0) {
try {
//Do something...
//Thread.sleep(5000);
try
{
mediaPlayer.setDataSource(AudioUrlPath);
mediaPlayer.prepare();
mediaPlayer.start();
AudioPlaying=true;
}
catch (IOException e) {
Log.e(\"AudioFileError\",\"Could not open file \" + AudioUrlPath + \" for playback.\",e);
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(Void result) {
if (pd!=null) {
pd.dismiss();
//b.setEnabled(true);
}
}
};
task.execute((Void[])null);
, 这是活动课程。在这里我仅显示路线。
package com.android.mediaactivity;
import android.app.Activity;
import android.os.Bundle;
import android.widget.LinearLayout;
import android.widget.ProgressBar;
public class MediaActivity extends Activity
{
public LinearLayout mainLayout;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mainLayout=(LinearLayout)findViewById(R.id.mainlinear);
MediaPlayer media=new MediaPlayer(this);
media.startPlayer();
}
}
这是mediaplayerclass。
package com.android.mediaactivity;
import java.io.IOException;
import android.media.MediaPlayer.OnPreparedListener;
public class MediaPlayer implements OnPreparedListener {
MediaActivity mediaActivity;
android.media.MediaPlayer mediaPlayer;
public MediaPlayer(MediaActivity mediaActivity) {
this.mediaActivity = mediaActivity;
}
public void startPlayer() {
mediaPlayer = new android.media.MediaPlayer();
mediaPlayer.setOnPreparedListener(this);
mediaPlayer.reset();
try {
mediaPlayer.setDataSource(\"\");
mediaPlayer.prepareAsync();
toggleProgress(true);
} catch (IllegalArgumentException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IllegalStateException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } public void onPrepared(android.media.MediaPlayer mp) { toggleProgress(false); mediaPlayer.start(); }
public void toggleProgress(final boolean show) {
mediaActivity.runOnUiThread(new Runnable() {
public void run() {
if (show) mediaActivity.mainLayout.setVisibility(mediaActivity.mainLayout.VISIBLE);
else mediaActivity.mainLayout.setVisibility(mediaActivity.mainLayout.INVISIBLE);
}
});
}
}
}
}
这是main.xml
<?xml version=\"1.0\" encoding=\"utf-8\"?>
<LinearLayout xmlns:android=\"http://schemas.android.com/apk/res/android\"
android:orientation=\"vertical\" android:layout_width=\"fill_parent\"
android:layout_height=\"fill_parent\" android:id=\"@+id/mainlinear\"
android:visibility=\"invisible\">
<ProgressBar android:id=\"@+id/ProgressBar01\"
android:layout_width=\"wrap_content\" android:layout_height=\"wrap_content\"></ProgressBar>
</LinearLayout>
, 当您在基础mediaplayer
对象上说prepare
时,它实际上在内部进行了一些准备工作,例如-设置文件的提取器,设置音频解码器以解码编码的音频文件以及设置音频接收器以播放原始音频数据,从解码器解码。现在所有这一切都需要时间,它不是瞬时的。
因此,在您的原始代码中,您检查媒体播放器isPlaying
,然后将其关闭,但问题在于此时媒体播放器还没有播放音频,因此从未调用过关闭,因此它始终可见。
您需要做的是实现侦听器MediaPlayer.OnPreparedListener
,并在应用程序中调用方法onPrepared
时,在该方法中调用dismissmediaPlayerLoadingBar.dismiss();
。
, 这是我的解决方案:
用于准备音频的prepareAsync函数是非阻塞操作(它不阻塞应用程序的主线程)。
然后,我使用回调setOnPreparedListener来获取通知,
prepareAsync返回,并且音频准备就绪
public void playAudio(String audioFile){
//init the progress dialog
final ProgressDialog progressDialog = new ProgressDialog(SubjectActivity.this);
try {
progressDialog.setCancelable(false);
progressDialog.setMessage(\" Waiting to Prepare ...\");
progressDialog.show();
// pass the url file to the media player
mediaplayer.setDataSource(audioFile);
mediaplayer.prepareAsync();
} catch (IllegalArgumentException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SecurityException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalStateException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
//the callback gets called when prepareAsync audio file become ready,mediaplayer.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
@Override
public void onPrepared(MediaPlayer mp) {
mediaplayer.start();
// cancel the dialog
progressDialog.cancel();
}
});
}