在开发自定义图片查看中有一个功能是删除本地图片。同时图片查看中有一个功能是收藏图片，收藏的图片存入了自己写的一个图片收藏的表里了。页面如下：

要删除图片，要分两种情况，一种是该图片是收藏的图片，一种是不是。如果不是收藏的图片，则只需直接删除文件，同时通知系统更新本地图片媒体库。如果是收藏的图片，除了上述操作，还需要删除在收藏图片的表中对应的图片。

private void deleteImage(String imgPath) {   
        String imgRealPath = getRealPathFromUri(activity,Uri.parse(imgPath));  
        Log.e(TAG, "deleteImage,imgRealPath:"+imgRealPath+",imgPath："+imgPath);//imgRealPath:/storage/emulated/0/faceallRecog/IMG_20171024_140811.jpg，
imgPath:content://media/external/images/media/7556
 ContentResolver resolver = activity.getContentResolver(); Cursor cursor = MediaStore.Images.Media.query(resolver, MediaStore.Images.Media.EXTERNAL_CONTENT_URI, new String[] { MediaStore.Images.Media._ID }, MediaStore.Images.Media.DATA +
 "=?", new String[] { imgRealPath }, null); boolean result = false; if (cursor.moveToFirst()) { long id = cursor.getLong(0); Uri contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI; Uri uri = ContentUris.withAppendedId(contentUri, id); int count = activity.getContentResolver().delete(uri,
 null, null); result = count == 1; } else { File file = new File(imgRealPath); result = file.delete(); } //如果要删除的图片是收藏的图片，则要从收藏的表里删除 if(favFlag) { helper.deleteFavouritesImg(imgId); } if (result) { currentLabelList.remove(imgRealPath); myAdapter.notifyDataSetChanged();
 showToast(activity,"删除成功"); } }


/**
     * 根据图片的uri获取图片的绝对路径
     * @param context
     * @param uri
     * @return
     */
    public static String getRealPathFromUri(Context context, Uri uri){
        if(context == null || uri == null) {
            return null;
        }
        if("file".equalsIgnoreCase(uri.getScheme())) {
            return getRealPathFromUri_Byfile(context,uri);
        } else if("content".equalsIgnoreCase(uri.getScheme())) {
            return getRealPathFromUriApi11to18(context,uri);
        }
        return getRealPathFromUri_AboveApi19(context,uri);
    }

    /**
     * 适配api19以上,根据uri获取图片的绝对路径
     * @param context
     * @param uri
     * @return
     */
    @SuppressLint("NewApi")
    private static String getRealPathFromUri_AboveApi19(Context context, Uri uri) {
        String filePath = null;
        String wholeId = null;
        wholeId = DocumentsContract.getDocumentId(uri);
        //使用“:”分割
        String id = wholeId.split(":")[1];
        String[] projection = {MediaStore.Images.Media.DATA};
        String selection = MediaStore.Images.Media._ID + "=?";
        String[] selectionArgs = {id};
        Cursor cursor = context.getContentResolver().query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, projection, selection, selectionArgs, null);
        int columnIndex = cursor.getColumnIndex(projection[0]);
        if(cursor.moveToFirst()) {
            filePath = cursor.getString(columnIndex);
        }
        cursor.close();
        return filePath;
    }

    /**
     * 适配api11-api18,根据uri获取图片的绝对路径。
     * 针对图片URI格式为Uri:: content://media/external/images/media/1028
     * @param context
     * @param uri
     * @return
     */
    private static String getRealPathFromUriApi11to18(Context context, Uri uri) {
        String filePath = null;
        String[] projection = {MediaStore.Images.Media.DATA};
        CursorLoader cursorLoader = new CursorLoader(context,uri,projection,null,null,null);
        Cursor cursor = cursorLoader.loadInBackground();
        if(cursor != null) {
            cursor.moveToFirst();
            filePath = cursor.getString(cursor.getColumnIndex(projection[0]));
            cursor.close();
        }
        return filePath;
    }

    //针对图片URI格式为Uri:: file:///storage/emulated/0/DCIM/Camera/IMG_20170613_132837.jpg
    private static String getRealPathFromUri_Byfile(Context context, Uri uri) {
        String uri2Str = uri.toString();
        String filePath = uri2Str.substring(uri2Str.indexOf(":") + 3);
        return filePath;
    }
 //图片收藏取消
    public void deleteFavouritesImg(int imgId){
        db = mDatabaseHelper.getWritableDatabase();
        db.execSQL("delete from "+TAB_FAVOURITES + " where "+FAV_IMG_ID+" = ? ",new Object[]{imgId});
    }
现在的问题是不能实时刷新，只能重新进入页面才能看到删除的结果。这一点需要继续改进。




http://blog.csdn.net/dingxu_ren/article/details/38823591


http://blog.csdn.net/mingyunxiaohai/article/details/72772126

http://blog.csdn.net/yanzi1225627/article/details/29252665

http://www.jianshu.com/p/c283fd5413d5