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 sysVideoList = null;// 视频信息集合

sysVideoList = new ArrayList();

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())));