未能提供結果ResultInfo時挑文件是從文件管理器

Question

有意向的音頻文件選擇它做工精細，正確的，但是當我選擇從文件管理器應用程序崩潰的MP3文件，並給我下面的日誌：

E/AndroidRuntime: FATAL EXCEPTION: main 
        java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=1, result=-1, data=Intent { dat=file:///mnt/sdcard/Download/g.p.mp3 }} to activity {com.example.er.part2/com.example.er.part2.Main2Activity}: java.lang.NullPointerException 
         at android.app.ActivityThread.deliverResults(ActivityThread.java:3141) 
         at android.app.ActivityThread.handleSendResult(ActivityThread.java:3184) 
         at android.app.ActivityThread.access$1100(ActivityThread.java:130) 
         at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1243) 
         at android.os.Handler.dispatchMessage(Handler.java:99) 
         at android.os.Looper.loop(Looper.java:137) 
         at android.app.ActivityThread.main(ActivityThread.java:4745) 
         at java.lang.reflect.Method.invokeNative(Native Method) 
         at java.lang.reflect.Method.invoke(Method.java:511) 
         at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) 
         at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 
         at dalvik.system.NativeStart.main(Native Method) 
        Caused by: java.lang.NullPointerException 
         at com.example.er.part2.Main2Activity.getRealPathFromURI(Main2Activity.java:128) 
         at com.example.er.part2.Main2Activity.onActivityResult(Main2Activity.java:98) 
         at android.app.Activity.dispatchActivityResult(Activity.java:5192) 
         at android.app.ActivityThread.deliverResults(ActivityThread.java:3137) 
         at android.app.ActivityThread.handleSendResult(ActivityThread.java:3184)  
         at android.app.ActivityThread.access$1100(ActivityThread.java:130)  
         at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1243)  
         at android.os.Handler.dispatchMessage(Handler.java:99)  
         at android.os.Looper.loop(Looper.java:137)  
         at android.app.ActivityThread.main(ActivityThread.java:4745)  
         at java.lang.reflect.Method.invokeNative(Native Method)  
         at java.lang.reflect.Method.invoke(Method.java:511)  
         at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)  
         at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)  
         at dalvik.system.NativeStart.main(Native Method)  

這是我的代碼：

Button button=(Button)findViewById(R.id.select); 
    button.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View view) { 

      Intent intent_upload = new Intent(); 
      intent_upload.setType("audio/*"); 
      intent_upload.setAction(Intent.ACTION_GET_CONTENT); 
      startActivityForResult(intent_upload,1); 

     } 
    }); 
public void onActivityResult(int requestCode, int resultCode, Intent data) { 
     super.onActivityResult(requestCode, resultCode, data); 


     if (requestCode == 1 && resultCode == Activity.RESULT_OK){ 
      if ((data != null) && (data.getData() != null)){ 
       audioFileUri = data.getData(); 
       // Now you can use that Uri to get the file path, or upload it, ... 
       filePath = getRealPathFromURI(getApplicationContext(),audioFileUri); 
    } 
} 
    public String getRealPathFromURI(Context context, Uri contentUri) { 
     Cursor cursor = null; 
     try { 
      String[] proj = { MediaStore.Audio.Media.DATA }; 
      cursor = context.getContentResolver().query(contentUri, proj, null, null, null); 
      int column_index = cursor.getColumnIndex(MediaStore.Audio.Media.DATA); 
      cursor.moveToFirst(); 
      return cursor.getString(column_index); 
     } finally { 
      if (cursor != null) { 
       cursor.close(); 
      } 
     } 
    } 

正如我告訴當從媒體播放器的選擇，但是當從它發生的文件管理器選擇它做工精細！以下從日誌

Caused by: java.lang.NullPointerException at com.example.er.part2.Main2Activity.getRealPathFromURI(Main2Activity.java:128) 

點這一行部分：

int column_index = cursor.getColumnIndex(MediaStore.Audio.Media.DATA); 

Answer 1

當從媒體播放器選擇它做工精細

它只會在某些設備上，並在一些工作的情況。

擺脫getRealPathFromURI()。使用ContentResolver和openInputStream()來訪問由Uri標識的內容。

Answer 2

經過一番研究，我發現這種方法和解決問題

@SuppressLint("NewApi") 
public static String getFilePath(Context context, Uri uri) throws URISyntaxException { 
    String selection = null; 
    String[] selectionArgs = null; 
    // Uri is different in versions after KITKAT (Android 4.4), we need to 
    if (Build.VERSION.SDK_INT >= 19 && DocumentsContract.isDocumentUri(context.getApplicationContext(), uri)) { 
     if (isExternalStorageDocument(uri)) { 
      final String docId = DocumentsContract.getDocumentId(uri); 
      final String[] split = docId.split(":"); 
      return Environment.getExternalStorageDirectory() + "/" + split[1]; 
     } else if (isDownloadsDocument(uri)) { 
      final String id = DocumentsContract.getDocumentId(uri); 
      uri = ContentUris.withAppendedId(
        Uri.parse("content://downloads/public_downloads"), Long.valueOf(id)); 
     } else if (isMediaDocument(uri)) { 
      final String docId = DocumentsContract.getDocumentId(uri); 
      final String[] split = docId.split(":"); 
      final String type = split[0]; 
      if ("audio".equals(type)) { 
       uri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI; 
      } 
      selection = "_id=?"; 
      selectionArgs = new String[]{ 
        split[1] 
      }; 
     } 
    } 
    if ("content".equalsIgnoreCase(uri.getScheme())) { 
     String[] projection = { 
       MediaStore.Audio.Media.DATA 
     }; 
     Cursor cursor = null; 
     try { 
      cursor = context.getContentResolver() 
        .query(uri, projection, selection, selectionArgs, null); 
      int column_index = cursor.getColumnIndexOrThrow(MediaStore.Audio.Media.DATA); 
      if (cursor.moveToFirst()) { 
       return cursor.getString(column_index); 
      } 
     } catch (Exception e) { 
     } 
    } else if ("file".equalsIgnoreCase(uri.getScheme())) { 
     return uri.getPath(); 
    } 
    return null; 
} 

public static boolean isExternalStorageDocument(Uri uri) { 
    return "com.android.externalstorage.documents".equals(uri.getAuthority()); 
} 

public static boolean isDownloadsDocument(Uri uri) { 
    return "com.android.providers.downloads.documents".equals(uri.getAuthority()); 
} 

public static boolean isMediaDocument(Uri uri) { 
    return "com.android.providers.media.documents".equals(uri.getAuthority()); 
}