如何判断文件呢? 可以通过Cursor遍历数据库，对比INTERNAL_CONTENT_URI字段的值，这是一个Uri，这里保存着Android手机SD卡上的多媒体文件完整路径。

[java]
复制代码 代码如下:
Uri originalUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
//若为视频则为MediaStore.Video.Media.EXTERNAL_CONTENT_URI;
ContentResolver cr = this.getContentResolver();
Cursor cursor = cr.query(originalUri, null, null, null, null);
if (cursor == null) {
return;
}
for (cursor.moveToFirst();!cursor.isAfterLast(); cursor.moveToNext()) {
long thumbNailsId = cursor.getLong(cursor .getColumnIndex("_ID"));
Bitmap bitmap = MediaStore.Images.Thumbnails.getThumbnail(cr,
thumbNailsId, Video.Thumbnails.MICRO_KIND, null);
//若为视频则为
// Bitmap bitmap = MediaStore.Video.Thumbnails.getThumbnail(cr,
// thumbNailsId, Video.Thumbnails.MICRO_KIND, null);
return bitmap;
}

Uri originalUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
//若为视频则为MediaStore.Video.Media.EXTERNAL_CONTENT_URI;
ContentResolver cr = this.getContentResolver();
Cursor cursor = cr.query(originalUri, null, null, null, null);
if (cursor == null) {
return;
}
for (cursor.moveToFirst();!cursor.isAfterLast(); cursor.moveToNext()) {
long thumbNailsId = cursor.getLong(cursor .getColumnIndex("_ID"));
Bitmap bitmap = MediaStore.Images.Thumbnails.getThumbnail(cr,
thumbNailsId, Video.Thumbnails.MICRO_KIND, null);
//若为视频则为
// Bitmap bitmap = MediaStore.Video.Thumbnails.getThumbnail(cr,
// thumbNailsId, Video.Thumbnails.MICRO_KIND, null);
return bitmap;
}