android当中获取视频音频的时长，三种。

1：获取视频URI后获取cursor

cursor.getLong(cursor.getColumnIndexOrThrow(MediaStore.Video.Media.DURATION));

2：根据MediaPlayer获取：

MediaPlayer mediaPlayer = new MediaPlayer();

mediaPlayer.setDataSource(url);

mediaPlayer.prepare();

mediaPlayer.getDuration();

3:采用MediaMetadataRetriever的方式：

public static String getRingDuring(String mUri){

String duration=null;

android.media.MediaMetadataRetriever mmr = new android.media.MediaMetadataRetriever();

try { if (mUri != null) { HashMap headers=null;

if (headers == null) { headers = new HashMap();

headers.put("User-Agent", "Mozilla/5.0 (Linux; U; Android 4.4.2; zh-CN; MW-KW-001 Build/JRO03C) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 UCBrowser/1.0.0.001 U4/0.8.0 Mobile Safari/533.1"); }

mmr.setDataSource(mUri, headers); }

duration = mmr.extractMetadata(android.media.MediaMetadataRetriever.METADATA_KEY_DURATION); }

catch (Exception ex) { }

finally { mmr.release(); }

LogUtil.e("ryan","duration "+duration); return duration; }