Android:如何访问音频文件？
Android:如何访问音频文件？
提问于 2012-10-29 14:15:18
在我的应用程序中，我使用这个方法来访问音频文件：
public Cursor pobierzPlikiAudio(){
String[] STAR = {"*"};
String selection = MediaStore.Audio.Media.IS_MUSIC + " != 0";
Uri uri= Uri.parse("content://pl/aplikacja/app/provider/MediaStore/Audio");
return getContentResolver().query(uri, STAR, selection, null, null);
}但在我的LogCat中，我得到了一个nullPointerException。怎么啦？
出现错误的Logcat：
10-29 07:04:17.729: E/AndroidRuntime(24354): FATAL EXCEPTION: main
10-29 07:04:17.729: E/AndroidRuntime(24354): java.lang.RuntimeException: Unable to start activity ComponentInfo{pl.aplikacja.app/pl.aplikacja.app.MainActivity}: java.lang.NullPointerException
10-29 07:04:17.729: E/AndroidRuntime(24354): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1967)
10-29 07:04:17.729: E/AndroidRuntime(24354): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1992)
10-29 07:04:17.729: E/AndroidRuntime(24354): at android.app.ActivityThread.access$600(ActivityThread.java:127)
10-29 07:04:17.729: E/AndroidRuntime(24354): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1158)
10-29 07:04:17.729: E/AndroidRuntime(24354): at android.os.Handler.dispatchMessage(Handler.java:99)
10-29 07:04:17.729: E/AndroidRuntime(24354): at android.os.Looper.loop(Looper.java:137)
10-29 07:04:17.729: E/AndroidRuntime(24354): at android.app.ActivityThread.main(ActivityThread.java:4441)
10-29 07:04:17.729: E/AndroidRuntime(24354): at java.lang.reflect.Method.invokeNative(Native Method)
10-29 07:04:17.729: E/AndroidRuntime(24354): at java.lang.reflect.Method.invoke(Method.java:511)
10-29 07:04:17.729: E/AndroidRuntime(24354): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
10-29 07:04:17.729: E/AndroidRuntime(24354): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
10-29 07:04:17.729: E/AndroidRuntime(24354): at dalvik.system.NativeStart.main(Native Method)
10-29 07:04:17.729: E/AndroidRuntime(24354): Caused by: java.lang.NullPointerException
10-29 07:04:17.729: E/AndroidRuntime(24354): at pl.aplikacja.app.MainActivity.onCreate(MainActivity.java:18)
10-29 07:04:17.729: E/AndroidRuntime(24354): at android.app.Activity.performCreate(Activity.java:4465)
10-29 07:04:17.729: E/AndroidRuntime(24354): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
10-29 07:04:17.729: E/AndroidRuntime(24354): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1931)
10-29 07:04:17.729: E/AndroidRuntime(24354): ... 11 more这是MainActivity.java
package pl.aplikacja.app;
import android.os.Bundle;
import android.database.Cursor;
import android.app.Activity;
import android.view.Menu;
import android.widget.TextView;
import android.provider.MediaStore;
public class MainActivity extends Activity {
private Dostawca dostawca;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Cursor tablicaPlikow = dostawca.pobierzPlikiAudio();
if (tablicaPlikow.moveToFirst()) {
String title;
String artist;
String album;
int titleColumn = tablicaPlikow.getColumnIndex(MediaStore.EXTRA_MEDIA_TITLE);
int artistColumn = tablicaPlikow.getColumnIndex(MediaStore.EXTRA_MEDIA_ARTIST);
int albumColumn =tablicaPlikow.getColumnIndex(MediaStore.EXTRA_MEDIA_ALBUM);
// Get the field values
title = tablicaPlikow.getString(titleColumn);
artist = tablicaPlikow.getString(artistColumn);
album = tablicaPlikow.getString(albumColumn);
TextView widok = (TextView) findViewById(R.id.tekst);
widok.setText(""+title+" "+ artist + " " + album);
}
setContentView(R.layout.activity_main);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
}Stack Overflow用户
发布于 2015-05-13 16:32:37
使用此代码
public void getAllSongsFromSDCARD()
{
String[] STAR = { "*" }; //it is projection you can modify it according to your need
String sortOrder = MediaStore.Audio.Media.TITLE + " ASC";
String[] selectionArgs = null;
Uri allsongsuri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
String selection = MediaStore.Audio.Media.IS_MUSIC + " != 0"; // check for music files
cursor = getContentResolver().query(allsongsuri,STAR,selection,selectionArgs,sortOrder );
if (cursor != null) {
if (cursor.moveToFirst()) {
do {
String song_name = cursor
.getString(cursor
.getColumnIndex(MediaStore.Audio.Media.DISPLAY_NAME));
int song_id = cursor.getInt(cursor
.getColumnIndex(MediaStore.Audio.Media._ID));
String fullpath = cursor.getString(cursor
.getColumnIndex(MediaStore.Audio.Media.DATA));
String album_name = cursor.getString(cursor
.getColumnIndex(MediaStore.Audio.Media.ALBUM));
int album_id = cursor.getInt(cursor
.getColumnIndex(MediaStore.Audio.Media.ALBUM_ID));
String artist_name = cursor.getString(cursor
.getColumnIndex(MediaStore.Audio.Media.ARTIST));
int artist_id = cursor.getInt(cursor
.getColumnIndex(MediaStore.Audio.Media.ARTIST_ID));
} while (cursor.moveToNext());
}
cursor.close();
}
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/13116708
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