Glide uses disk caching (both internal and external). The way it stores the file name is encoded in some format. It is possible to get the original file name/file path, where the image is downloaded ?
Glide uses a two-level cache in 3.x: SOURCE and RESULT. The default caching (if you don't specify a .diskCacheStrategy() is RESULT. Currently there's no public way to figure out which file corresponds to a normal Glide load (RESULT cache).
The main article about caching is: https://github.com/bumptech/glide/wiki/Caching-and-Cache-Invalidation
Many have tried to mess with the cache.
The solution is based on your use case and you can choose one of:
.sigunature(): invalidate a single item in cache when signature changes
.downloadOnly(): get the File handle to a SOURCE cache item
.asBytes(): returns JPG/PNG encoded byte[] instead of a Drawable/Bitmap
Glide.get(context).clearDiskCache(): last resort only, removes everything
Related
I´m using the FileServlet from Omnifaces:
http://showcase.omnifaces.org/servlets/FileServlet
It works fine and all my images appears in my webapp.
But now I would like to change the link from the image because I would like to avoid that someone enter the path from another image:
For example:
The path from one image is:
myapp/imagesservlet/mypic1.jpg
-> Someone can enter
myapp/imagesservlet/mypic2.jpg -> and got another image.
My files are stored as:
mypic like mypic1.jpg, mypic2.jpg.....
Is there any chance to change the path and got also the correct image?
Just use unpredictable autogenerated filenames. E.g. imgur also does that. This responsibility is actually beyond the OmniFaces FileServlet as all it does is just inspecting the passed-in filename and serving it up. You should change the passed-in filename to be an autogenerated one. Save if necessary the original filename somewhere else, e.g. in a SQL database, if necessary along with other metadata (content type, size, etc) so it can more efficiently be indexed and searched.
How to autogenerate a random string in Java is already covered in this Q&A: How to generate a random alpha-numeric string?
My Mysql database stores images (in PNG, JPG)of our personnel and it's field type is set to longblob.
Is there any possibility to load blob data type using HttpService and render it in Image component in Flex .??? ^..^
I'm eager to know about as it comes in handy in the nearest future!!!
You can, but I don't see the point of storing your images in a DB.
Simplest way to get it into an Image is to load the blob, convert to a ByteArray which you can set as the source of of said Image.
If you override HttpService you can use it to receive binary data. If you don't want to override HttpService you have the option of encoding you binary data in base64 before sending it.
But if have the option to store the images in a directory on the server and just send links to the client - that would be a better solution.
I am using file upload mechanism to upload file for an employee and converting it into byte[] and passing it to varBinary(Max) to store into database.
Now I what I have to do is, if any file is already uploaded for employee, simply read it from table and show file name. I have only one column to store a file and which is of type VarBinary.
Is it possible to get all file information from VarBinary field?
Any other way around, please let me know.
If you're not storing the filename, you can't retrieve it.
(Unless the file itself contains its filename in which case you'd need to parse the blob's contents.)
If the name of the file (and any other data about the file that's not part of the file's byte data) needs to be used later, then you need to save that data as well. I'd recommend adding a column for the file name, perhaps one for its type (mime type or something like that for properly sending it back to the client's browser, etc.) and maybe even one for size so you don't have to calculate that on the fly for each file (useful when displaying a grid of files and not wanting to touch the large blob field in the query that populates the grid).
Try to stay away from using the file name for system-internal identity purposes. It's fine for allowing the users to search for a file by name, select it, etc. But when actually making the request to the server to display the file it's better to use a simple integer primary key from the table to actually identify it. (On a side note, it's probably a good idea to put a unique constraint on the file name column.)
If you also need help displaying the file to the user, you'll probably want to take the approach that's tried and true for displaying images from a database. Basically it involves having a resource (generally an .aspx page, but could just as well be an HttpHandler instead) which accepts the file ID as a query string parameter and outputs the file.
This resource would have no UI (remove everything from the .aspx except the Page directive) and would manually manipulate the response headers (this is where you'd set the content type from the file's type), write the byte stream to the client, and end the response. From the client's perspective, something like ~/MyContent/MyFile.aspx?fileID=123 would be the file. (You can suggest a file name to the browser for saving purposes in the response headers, which you'd probably want to do with the file's stored name.)
There's no shortage of quick tutorials (some several years old, it's been around for a while) on how to do this with images. Just remember that there's essentially no difference from the server's perspective if it's an image or any other kind of file. All the server needs to do is send the type in the response headers and write the file's bytes to the client. How the client handles the file is up to the browser. In the vast majority of cases, the browser will know what to do (display an image, display via a plugin a PDF, save a .doc, etc.).
I able to upload my file through uploadify + .ashx, but the problem is I always get ContentType = application/octet-stream
Lets say I upload an image, I expected to return me "image/pjpeg", but it always return "application/octet-stream" no matter what file I uploaded.
Please advice how to get the correct contentType in .ashx
I believe that most probably content type is getting set by browser. Regardless, different browsers may set different content type for different files - and they may fall back to generic content type such as "application/octet-stream" for any binary file (pdf, zip, doc, xls). Its possible that one browser would report docx as "application/vnd.openxmlformats" while other as ""application/x-zip-compressed" and yet another as "application/octet-stream". And yet all of them are correct, because docx are binary file and are compressed (zip) files.
In short, my suggestion is that you should not rely on the content type sent by client (beyond certain extent such as deciding whether its text, html or binary etc) and rather use server side sniffing logic to determine type of file content. Simple sniffing can be based on file extension while more robust implementation will loot at actual file contents where typically first few bytes of file indicate the file type.
i use such code
string.Format("<img src='{0}'><br>", u.Avatar);
u.Avatar-it's like '/img/path/pic.jpg'
but in this site i can upload new image instead old pic.jpg. so picture new, but name is old. and browser show OLD picture (cache). if i put random number like /img/path/pic.jpg?123 then works fine, but i need it only ufter upload, not always. how can i solve this?
string imgUrl = _
string.Format("<img src='{0}?{1}'><br>", _
u.Avatar, _
FunctionThatLookupFileSystemForItsLastModified(u.Avatar).Ticks.ToString());
Instead of linking to the images directly, consider setting up a generic HTTP handler to serve the images.
MSDN: HTTP Handlers and HTTP Modules Overview
Stack Overflow: How to use output caching on .ashx handler
Append DateTime.Now.Ticks to the image url:
string imgUrl =
string.Format("<img src='{0}?{1}'><br>", u.Avatar,DateTime.Now.Ticks);
EDIT: I don' think this best practice are even a practice I would use. This is just a suggestion given the limited information given in case the Random implementation isn't truly Random.
Read your post again,,, sorry for general answer.
To workaround it do following
On Application_Start create a Dictionary with uploaded images save it on Application object, set it to null. Once you upload an image add it to this Dictionary. Wrap every place avatars appear on your website with function that evaluates image in Dictionary if found return imagename.jpg?randomnumber and then delete it from a Dictionary else return just an imagename.jpg.
This is going to be heavy because you will need to check each image in Dictionary but this will do exactly what you need.
You can set cache dependancy using the System.Web.Caching.CacheDependency namespace.
This can set the dependancy on the file uploaded, and will release the cache for that file automatically when the file changes.
There are lots of articles and stuff on MSDN and other places so I will not go into details on all that level of detail.
You can do inserts, deletes and other management of cache using the tools available.
(and this does not require you to change the file names or tack on stuff - it knows by the file system that the file changed)