Android保存图片到本地图库

Android保存图片到本地图库

• 主要通过ContentResolver和Images.Media类相关的功能实现。
• Images.Media类的相关属性：

/**
         * The display name of the file
         * <P>Type: TEXT</P>
         */
        public static final String DISPLAY_NAME = "_display_name";

        /**
         * The title of the content
         * <P>Type: TEXT</P>
         */
        public static final String TITLE = "title";

        /**
         * The time the file was added to the media provider
         * Units are seconds since 1970.
         * <P>Type: INTEGER (long)</P>
         */
        public static final String DATE_ADDED = "date_added";

        /**
         * The time the file was last modified
         * Units are seconds since 1970.
         * NOTE: This is for internal use by the media scanner.  Do not modify this field.
         * <P>Type: INTEGER (long)</P>
         */
        public static final String DATE_MODIFIED = "date_modified";

• 通过ContentValues 存储要保存的图片信息，添加修改时间和添加时间使图片保存在图库的前面

ContentValues values = new ContentValues();
        values.put(Images.Media.TITLE, title);
        values.put(Images.Media.DISPLAY_NAME, title);
        values.put(Images.Media.DESCRIPTION, description);
        values.put(Images.Media.MIME_TYPE, "image/jpeg");
        // Add the date meta data to ensure the image is added at the front of the gallery
        values.put(Images.Media.DATE_ADDED, System.currentTimeMillis());//添加时间
        values.put(Images.Media.DATE_TAKEN, System.currentTimeMillis());
        values.put(Images.Media.DATE_MODIFIED, System.currentTimeMillis()/1000);//增加修改时间

• 通过ContentResolver的insert方法插入图库，update方法更新图库

Uri url = null;
try {
      url = cr.insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, values);

      if (source != null) {//图片
          OutputStream imageOut = cr.openOutputStream(url);
          try {
              source.compress(Bitmap.CompressFormat.JPEG, 100, imageOut);
          } finally {
              imageOut.close();
          }

          long id = ContentUris.parseId(url);
          // Wait until MINI_KIND thumbnail is generated.
          Bitmap miniThumb = Images.Thumbnails.getThumbnail(cr, id, Images.Thumbnails.MINI_KIND, null);
          // This is for backward compatibility.
          storeThumbnail(cr, miniThumb, id, 50F, 50F,Images.Thumbnails.MICRO_KIND);//跟新缓存
          cr.update(url, values, null, null);//更新图库
      } else {
          cr.delete(url, null, null);
          url = null;
      }
  } catch (Exception e) {
      if (url != null) {
          cr.delete(url, null, null);
          url = null;
      }
  }

• 插入图片代码

public static final String insertImage(ContentResolver cr,
                                           Bitmap source,
                                           String title,
                                           String description) {

        ContentValues values = new ContentValues();
        values.put(Images.Media.TITLE, title);
        values.put(Images.Media.DISPLAY_NAME, title);
        values.put(Images.Media.DESCRIPTION, description);
        values.put(Images.Media.MIME_TYPE, "image/jpeg");
        // Add the date meta data to ensure the image is added at the front of the gallery
        //增加时间信息，让图片显示在图库的前面
        values.put(Images.Media.DATE_ADDED, System.currentTimeMillis());
        values.put(Images.Media.DATE_TAKEN, System.currentTimeMillis());
        values.put(Images.Media.DATE_MODIFIED, System.currentTimeMillis()/1000);//增加修改时间

        Uri url = null;
        String stringUrl = null;    /* value to be returned */

        try {
            url = cr.insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, values);

            if (source != null) {
                OutputStream imageOut = cr.openOutputStream(url);
                try {
                    source.compress(Bitmap.CompressFormat.JPEG, 100, imageOut);
                } finally {
                    imageOut.close();
                }

                long id = ContentUris.parseId(url);
                // Wait until MINI_KIND thumbnail is generated.
                Bitmap miniThumb = Images.Thumbnails.getThumbnail(cr, id, Images.Thumbnails.MINI_KIND, null);
                // This is for backward compatibility.
                storeThumbnail(cr, miniThumb, id, 50F, 50F,Images.Thumbnails.MICRO_KIND);
                cr.update(url, values, null, null);//更新图库
            } else {
                cr.delete(url, null, null);
                url = null;
            }
        } catch (Exception e) {
            if (url != null) {
                cr.delete(url, null, null);
                url = null;
            }
        }

        if (url != null) {
            stringUrl = url.toString();
        }

        return stringUrl;
    }

//保存到缓存
private static final Bitmap storeThumbnail(
            ContentResolver cr,
            Bitmap source,
            long id,
            float width,
            float height,
            int kind) {

        // create the matrix to scale it
        Matrix matrix = new Matrix();

        float scaleX = width / source.getWidth();
        float scaleY = height / source.getHeight();

        matrix.setScale(scaleX, scaleY);

        Bitmap thumb = Bitmap.createBitmap(source, 0, 0,
                source.getWidth(),
                source.getHeight(), matrix,
                true
        );

        ContentValues values = new ContentValues(4);
        values.put(Images.Thumbnails.KIND,kind);
        values.put(Images.Thumbnails.IMAGE_ID,(int)id);
        values.put(Images.Thumbnails.HEIGHT,thumb.getHeight());
        values.put(Images.Thumbnails.WIDTH,thumb.getWidth());

        Uri url = cr.insert(Images.Thumbnails.EXTERNAL_CONTENT_URI, values);

        try {
            OutputStream thumbOut = cr.openOutputStream(url);
            thumb.compress(Bitmap.CompressFormat.JPEG, 100, thumbOut);
            thumbOut.close();
            return thumb;
        } catch (FileNotFoundException ex) {
            return null;
        } catch (IOException ex) {
            return null;
        }
    }