Android获取SD卡上图片和视频缩略图的小例子

      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]

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;
    }