我一直在致力于这个项目，以便在我们打开应用程序时自动在recyclerview中播放mp3文件。现在我面临的问题是一个例外。
这是我的MainActivity.java
public class MainActivity extends AppCompatActivity {
private static final String URL = "http://myurl.com/mylanguage/a_displays.php";
private RecyclerView recyclerView;
private RecyclerView.Adapter adapter;
private List<Radio> radioList;
ProgressDialog progressDialog;
long queueid,queueid1;
private ApplicationPreferences applicationPreferences;
DownloadManager dm;
private MediaPlayer mediaplayer;
int next = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
recyclerView = findViewById(R.id.recycler_view);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
applicationPreferences = new ApplicationPreferences(this);
radioList = new ArrayList<>();
mediaplayer = new MediaPlayer();
mediaplayer.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
@Override
public void onPrepared(MediaPlayer mp) {
mediaplayer.start();
}
});
adapter = new RadioAdapter(radioList,this);
applicationPreferences.getCodeValue();
final String codeValue = getIntent().getStringExtra("CODEINTENT");
//Log.d("valueID",codeValue);
int flag = getIntent().getIntExtra("chckDownload",0);
if(flag == 1)
{
String path = getExternalFilesDir(DIRECTORY_DOWNLOADS)+ "/" +codeValue+ "/uploads/";
Log.d("Files", "Path: " + path);
File directory = new File(path);
final File[] files = directory.listFiles();
final String [] myAray = new String[files.length];
Log.d("Files", "Size: "+ files.length);
myAray[next] = getExternalFilesDir(DIRECTORY_DOWNLOADS) + "/" + codeValue + "/uploads/" + files[next].getName();
Log.d("Files", "StringArray:" + myAray[next] + "index" + next);
Log.d("Files", "FileName:" + files[next].getName());
Radio rad = new Radio(0, files[next].getName());
radioList.add(rad);
do {
try {
mediaplayer.setDataSource(this, Uri.parse(myAray[next]));
mediaplayer.prepareAsync();
mediaplayer.start();
Log.d("ValueOfi", String.valueOf(next));
mediaplayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
@Override
public void onCompletion(MediaPlayer mp) {
mp.start();
next++;
}
});
} catch (IOException e) {
e.printStackTrace();
}
}while(next <= files.length);
}
else{
datadummy(codeValue);
}
recyclerView.setAdapter(adapter);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
public void listFilesForFolder(final File folder) {
for (final File fileEntry : folder.listFiles()) {
if (fileEntry.isDirectory()) {
listFilesForFolder(fileEntry);
} else {
System.out.println(fileEntry.getName());
Radio rad = new Radio(0,fileEntry.getName());
radioList.add(rad);
}
}
}
private void playmedia(String myAray[], String codeValue){
try {
Uri music_play = Uri.parse(getExternalFilesDir(DIRECTORY_DOWNLOADS) + "/" + codeValue + "/uploads/" + myAray[next]);
// MediaPlayer mp = MediaPlayer.create(this,music_play);
mediaplayer.setDataSource(this, music_play);
mediaplayer.prepareAsync();
mediaplayer.start();
next++;
Log.d("ValueOfi", String.valueOf(next));
} catch (IOException e) {
e.printStackTrace();
}
}
public void datadummy(final String codeVal) {
StringRequest stringRequest = new StringRequest(Request.Method.POST,URL,
new Response.Listener<String>() {
@Override
public void onResponse(String response){
try {
JSONArray array = new JSONArray(response);
for (int i = 0; i < array.length(); i++) {
//
Log.d("MusicName", String.valueOf(array.getJSONObject(i).getString("audio_sound")));
final String music_uri = "http://myurl.in/mylanguage/" + array.getJSONObject(i).getString("audio_sound");
Uri uri = Uri.parse(music_uri);
applicationPreferences.getCodeValue();
dm = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);
DownloadManager.Request request = new DownloadManager.Request(uri);
String.valueOf(request.setDestinationInExternalFilesDir(MainActivity.this,
DIRECTORY_DOWNLOADS + "/"+codeVal,
String.valueOf(array.getJSONObject(i).getString("audio_sound"))));
queueid = dm.enqueue(request);
}
BroadcastReceiver receiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (DownloadManager.ACTION_DOWNLOAD_COMPLETE.equals(action)) {
DownloadManager.Query req_query = new DownloadManager.Query();
req_query.setFilterById(queueid);
Cursor c = dm.query(req_query);
if (c.moveToFirst()) {
int columnIndex = c.getColumnIndex(DownloadManager.COLUMN_STATUS);
if (DownloadManager.STATUS_SUCCESSFUL == c.getInt(columnIndex)) {
File folder = new File(getExternalFilesDir(DIRECTORY_DOWNLOADS)+ "/" +codeVal+ "/uploads/" );
Log.d("asd", String.valueOf(folder));
listFilesForFolder(folder);
adapter.notifyDataSetChanged();
}
}
}
}
};
registerReceiver(receiver,new IntentFilter((DownloadManager.ACTION_DOWNLOAD_COMPLETE)));
Log.d("-response",response);
}catch (JSONException e){
e.printStackTrace();
Log.d("Main", "JsonException: " + e);
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
}) {
@Override
protected Map<String, String> getParams() {
Map<String, String> params = new HashMap<>();
params.put("album_code", codeVal);
return params;
}
};
RequestQueue requestqueue = Volley.newRequestQueue(this);
requestqueue.add(stringRequest);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.action_settings:
Intent intent = new Intent(MainActivity.this,HomeScreen.class);
startActivity(intent);
applicationPreferences.clearPreferences();
return true;
case R.id.action_refresh:
// User chose the "Favorite" action, mark the current item
// as a favorite...
return true;
default:
// If we got here, the user's action was not recognized.
// Invoke the superclass to handle it.
return super.onOptionsItemSelected(item);
}
}
}
这是我的logcat：
E / Android运行时：致命异常：主要 流程：com.teaminertia.user.radioapplication，PID：9625 java.lang.RuntimeException：无法启动活动ComponentInfo {com.teaminertia.user.radioapplication / com.teaminertia.user.radioapplication.MainActivity}：java.lang.IllegalStateException 在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2984） 在android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:3045） 在android.app.ActivityThread.-wrap14（ActivityThread.java） 在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1642） 在android.os.Handler.dispatchMessage（Handler.java:102） 在android.os.Looper.loop（Looper.java:154） 在android.app.ActivityThread.main（ActivityThread.java:6776） 在java.lang.reflect.Method.invoke（本机方法） 在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:1496） 在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:1386） 造成原因：java.lang.IllegalStateException 在android.media.MediaPlayer._setDataSource（本机方法） 在android.media.MediaPlayer.setDataSource（MediaPlayer.java:1323） 在android.media.MediaPlayer.setDataSource（MediaPlayer.java:1306） 在android.media.MediaPlayer.setDataSource（MediaPlayer.java:1216） 在android.media.MediaPlayer.setDataSource（MediaPlayer.java:1129） 在android.media.MediaPlayer.setDataSource（MediaPlayer.java:1075） 在android.media.MediaPlayer.setDataSource（MediaPlayer.java:1052） 在com.teaminertia.user.radioapplication.MainActivity.onCreate（MainActivity.java:107） 在android.app.Activity.performCreate（Activity.java:6955） 在android.app.Instrumentation.callActivityOnCreate（Instrumentation.java:1126） 在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2927） 在android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:3045） 在android.app.ActivityThread.-wrap14（ActivityThread.java） 在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1642） 在android.os.Handler.dispatchMessage（Handler.java:102） 在android.os.Looper.loop（Looper.java:154） 在android.app.ActivityThread.main（ActivityThread.java:6776） 在java.lang.reflect.Method.invoke（本机方法） 在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:1496） com.android.internal.os.ZygoteInit.main（ZygoteInit.java:1386）
我的目标是同时播放mp3文件
答案 0 :(得分：0)
setDataSource仅在MediaPlayer处于空闲状态时有效。在您的情况下，您得到IllegalStateException是因为您在setDataSource处于播放状态或未处于空闲状态时设置了MediaPlayer
mediaplayer.reset()方法将MediaPlayer重置为空闲状态（未初始化状态）
那么您就需要像这样再次对其进行初始化。
mediaPlayer.setDataSource(your_data_source);
mediaPlayer.prepare();
mediaPlayer.start();
因此您只需在设置setDataSource之前重置媒体播放器
here是媒体播放器的状态图