如何扫描出android系统媒体库中视频文件

android系统启动时会去扫描系统文件，并将系统支持的视频文件（mp4,3gp,wmv）扫描到媒体库（MediaStore）中，下面代码演示如何获得这些文件的信息：

public static List<VideoInfo> sysVideoList = null;// 视频信息集合
sysVideoList = new ArrayList<VideoInfo>();
setVideoList();

	private void setVideoList() {
		// MediaStore.Video.Thumbnails.DATA:视频缩略图的文件路径
		String[] thumbColumns = { MediaStore.Video.Thumbnails.DATA,
				MediaStore.Video.Thumbnails.VIDEO_ID };

		// MediaStore.Video.Media.DATA：视频文件路径；
		// MediaStore.Video.Media.DISPLAY_NAME : 视频文件名，如 testVideo.mp4
		// MediaStore.Video.Media.TITLE: 视频标题 : testVideo
		String[] mediaColumns = { MediaStore.Video.Media._ID,
				MediaStore.Video.Media.DATA, MediaStore.Video.Media.TITLE,
				MediaStore.Video.Media.MIME_TYPE,
				MediaStore.Video.Media.DISPLAY_NAME };

		cursor = managedQuery(MediaStore.Video.Media.EXTERNAL_CONTENT_URI,
				mediaColumns, null, null, null);
		
		if(cursor==null){
			Toast.makeText(SystemVideoChooseActivity.this, "没有找到可播放视频文件", 1).show();
			return;
		}
		if (cursor.moveToFirst()) {
			do {
				VideoInfo info = new VideoInfo();
				int id = cursor.getInt(cursor
						.getColumnIndex(MediaStore.Video.Media._ID));
				Cursor thumbCursor = managedQuery(
						MediaStore.Video.Thumbnails.EXTERNAL_CONTENT_URI,
						thumbColumns, MediaStore.Video.Thumbnails.VIDEO_ID
								+ "=" + id, null, null);
				if (thumbCursor.moveToFirst()) {
					info.setThumbPath(thumbCursor.getString(thumbCursor
							.getColumnIndex(MediaStore.Video.Thumbnails.DATA)));
				}
				info.setPath(cursor.getString(cursor
						.getColumnIndexOrThrow(MediaStore.Video.Media.DATA)));
				info.setTitle(cursor.getString(cursor
						.getColumnIndexOrThrow(MediaStore.Video.Media.TITLE)));
				
				info.setDisplayName(cursor.getString(cursor
						.getColumnIndexOrThrow(MediaStore.Video.Media.DISPLAY_NAME)));
				LogUtil.log(TAG, "DisplayName:"+info.getDisplayName());
				info.setMimeType(cursor
						.getString(cursor
								.getColumnIndexOrThrow(MediaStore.Video.Media.MIME_TYPE)));
				
				sysVideoList.add(info);
			} while (cursor.moveToNext());
		}
	}

有一点需要注意的是：系统的媒体库并不会在我们添加视频文件后自动更新，我们如何去手动扫描媒体库，或者重启系统才能从媒体库中得到更新的视频文件：

sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED, Uri.parse("file://"  
                + Environment.getExternalStorageDirectory())));