读取系统所有 图片 和缩略图

    /**       * 读取系统的 多媒体索引 获取 sd卡中的所有图片信息       */      public void initImagesIndex() {            ImageCache. imgDirPathList = new ArrayList<String>();            ImageCache. imagesIndex = new HashMap<String, List<Map<String, String>>>();            ContentResolver cr = mContext.getContentResolver();            String[] imagesProjection = { Images.ImageColumns. _ID, Images.ImageColumns.DATA , Images.ImageColumns.BUCKET_DISPLAY_NAME };             // 查询sd上所有的图片信息            Cursor cur = cr.query(Images.Media. EXTERNAL_CONTENT_URI, imagesProjection, null , null, null);             if (cur.moveToFirst()) {                   int _id; // 图片id                  String data; // 图片Path 具体路径                  String dirName; // 图片所在目录的名称                   int _idColumn = cur.getColumnIndex(Images.ImageColumns._ID );                   int data_idColcum = cur.getColumnIndex(Images.ImageColumns.DATA );                   int dispalyname_Column = cur.getColumnIndex(Images.ImageColumns.BUCKET_DISPLAY_NAME );                   do {                        _id = cur.getInt(_idColumn);                        data = cur.getString(data_idColcum);                        dirName = cur.getString(dispalyname_Column);                        HashMap<String, String> map = new HashMap<>();                        map.put(CommonConst.ImageMap. ID, _id + "");                        map.put(CommonConst.ImageMap. PATH, data);                        map.put(CommonConst.ImageMap. DIR_NAME, dirName);                         // 图片所在文件夹路径                        String imgDirPath = data.substring(0, data.lastIndexOf("/" ));                         if (!ImageCache.imagesIndex .containsKey(imgDirPath)) {                               // 当找不到 该图片所在文件夹路径 时 则创建一个新的List 并且注入到 Map 中                              List<Map<String, String>> list = new ArrayList<Map<String, String>>();                              list.add(map);                              ImageCache. imagesIndex.put(imgDirPath, list);                              Log. i(TAG, "img dir path = " + imgDirPath);                        } else {                               // 找到的话 在原有的List 添加该图片信息                              ImageCache. imagesIndex.get(imgDirPath).add(map);                        }                         // 给图片所在文件夹路径 List 添加值 便于 计算出 adapter 使用                         if (!ImageCache.imgDirPathList .contains(imgDirPath)) {                              ImageCache. imgDirPathList.add(imgDirPath);                        }                  } while (cur.moveToNext());            }            initImagesThumb();      }      /**       * 初始化 读取 缩略图信息       */      public void initImagesThumb() {            ContentResolver cr = mContext.getContentResolver();            String[] imagesProjection = { Thumbnails. IMAGE_ID, Thumbnails.DATA };            Cursor cur = cr.query(Thumbnails. EXTERNAL_CONTENT_URI, imagesProjection, null , null, null);             if (cur.moveToFirst()) {                  String imagID; // 图片Path 具体路径                  String imgThumbPath; // 图片所在目录的名称                   int imagID_column = cur.getColumnIndex(Thumbnails.IMAGE_ID );                   int imgThumbPath_column = cur.getColumnIndex(Thumbnails.DATA );                   do {                        imagID = cur.getString(imagID_column);                        imgThumbPath = cur.getString(imgThumbPath_column);                        ImageCache. imgThumbMap.put(imagID, imgThumbPath);                  } while (cur.moveToNext());            }      }