I have Flutter app which needs to load dynamic assets and content which I want to save for later use. I know about Assets I can have in build time at the folder "assets/" inside the app.
I want to download content using ZIP files and unzip them to app local folder so they won't delete in the next app update.
what are the folders Flutter allows me to add assets to at runtime?
You cannot dynamically add assets to Flutter app at runtime and that is why Shared_Preferences package was developed by the official Flutter_Dev Team.
https://pub.dev/packages/shared_preferences
If you want to store a File instead of bits of information then refer to the below example code (For a Image File):
Future getImage(ImageSource imageSource) async {
// using your method of getting an image
final File image = await ImagePicker.pickImage(source: imageSource);
// getting a directory path for saving
final String path = await getApplicationDocumentsDirectory().path;
// copy the file to a new path
final File newImage = await image.copy('$path/image1.png');
setState(() {
_image = newImage;
});}
If your still want to somehow add/delete files dynamically then the answer is that it is practically not possible because assets weren't designed to dynamically store files.
One should only use assets to store files which shall remain common for all users.
I am creating a web app using Spring Boot and JPA. I want to upload many images. I want those images to save in a storage and save the location of the file into database. I am not understanding how to achieve this?
After researching a lot, I have come to a solution. I have used Amazon AWS S3 for storing the media data. Amazon AWS S3 comes with its own library. It gives you rich api to upload the media files and having control over them. I have just uploaded the file into the S3 Bucket and saved the corresponding URL into the MYSQL database. Please comment if you need the corresponding codes.
I have encountered this problem in Django application.
What i did was just used amazon S3 bucket and store all the images. I get the location of the image which is in s3 and store it in mysql DB. when i need the image i just call the image from s3 and used it.
Accept Images as a zipstream(Faster)/binarystream or as a MultipartFile
Load the stream ZipInputStream zis = new ZipInputStream(inputStream);
load the stream to File using Java.IO.File class
Push the file data to file system(Same server machine or any non-sql Database)
save the Location in a DB using Spring data JPA
This is how I DID it.
I store my images as a LONGBLOB in my MySQL database so use columnDefinition = "LONGBLOB". In your HTML code for your upload button, make sure you include the multiple = "true" in your tag if you are using HTML.
In your Controller class make a multipart file that will get the images if you are using binding models and also, you need to have a Set/List of images so you can go through them all.
MultipartFile[] images = bindingModel.getImages();
Set<Image> newImages = new HashSet<>();
I have this neat for loop so I can go through all of my images:
for (MultipartFile multipartFileFOREACH : images)
{
Image newImage = new Image(multipartFileFOREACH.getBytes(), postEntity);//Image is an Entity here, postEntity is an object
newImages.add(newImage);
this.imageRepository.saveAndFlush(newImage);
}
this.articleRepository.saveAndFlush(articleEntity);
So, here I store my bytes into the LONGBLOB in the SQL database
Then for the actual view
Set<Image> imagesBytes = post.getImages();
List<String> images = new ArrayList<>();
for (Image image : imagesBytes)
{
images.add(Base64.getEncoder().encodeToString(image.getLink()));
}
My Image Entity has a link variable of type byte[]
Then I simply add the view for the HTML:
model.addAttribute("images", images);
use s3 bucket for storing image and my sql for storing the address of the image
Using MultipartFile you can upload the file.
Save the File in your server using Files.Copy through BufferedInputStream
Save the saved-location of your file in your database through Spring-Data repository.
There are three options to store your files.
a) in your local file system
b) store in db as bytes
c) use cloud service such as AWS S3 bucket
This is a good tutorial for setting up S3 bucket with SpringBoot applications.
https://medium.com/oril/uploading-files-to-aws-s3-bucket-using-spring-boot-483fcb6f8646
I am going through http://developer.xamarin.com/guides/cross-platform/xamarin-forms/working-with/images/
and trying to get the Local Images working with Android however I am experiencing some issues when attempting to do something in normal monodroid just as a further test. I'm using a SharedProject, just for reference.
I have added the test image at Resources/drawable (test1.png), and also setting the Build Action as AndroidResource as it describes, and if I do the following in Xamarin.Forms it works:-
Xamarin.Forms.Image myimage = new Image();
myimage.Source = ImageSource.FromFile("test1.png");
However, if I try and retrieve the same file via the following it comes back as null.
Android.Graphics.Bitmap objBitmapImage = Android.Graphics.BitmapFactory.DecodeFile("test1.png")
Does anyone know why this is null and how to correct?
The Xamarin.Forms FileImageSource has a fallback mode as it covers two different scenarios.
First it will check whether the file exists in the file system via the BitmapFactory.DecodeFile.
Should the file not exist as specified in the File property, then it will use BitmapFactory.DecodeResource to try and load the resource content as a secondary alternative.
FileImageSource for Android therefore isn't only just for files that exist in the file system but also for retrieving named resources also.
This link indicates that Android Resources are compiled into the application and therefore wouldn't be part of the file system as physical files.
Since test1.png is a Drawable you should use BitmapFactory.DecodeResource ()
string scr = "#drawable/test1.png";
ImageView iv = new ImageView(context);
Bitmap bm = BitmapFactory.DecodeFile(src);
if (bm != null)
iv.SetImageBitmap(bm);
In a Struts 1 Web App I can access images from a .jsp by
<img src="../../images/myImageName.png"/>
Am I also able to reference that image from a .java class in my source directory?
I am using iText and can fetch an image from a url
String imageUrl = "http://jenkov.com/images/" +
"20081123-20081123-3E1W7902-small-portrait.jpg";
Image image2 = Image.getInstance(new URL(imageUrl));
but if I try and fetch one from
Image image = Image.getInstance("../../images/myImageName.png"/);
It always looks in the bin folder of my server. How can I get the relativePath back to my image?
If the image is in the web app content directory then you need the app context relative path:
String relativeWebPath = "images/myImageName.png";
String absoluteDiskPath = getServletContext().getRealPath(relativeWebPath);
Would I do that? Not unless there's a good reason; I'd prefer either a path off the app context altogether (and the image could be streamed by the app, or set as a symlink, etc) or a classpath-based resource.
I created an Azure Storage account. I have a 400 megabytes .zip file that I want to put into blob storage for later use.
How can I do that without writing code? Is there some interface for that?
Free tools:
Visual Studio 2010 -- install Azure tools and you can find the blobs in the Server Explorer
Cloud Berry Lab's CloudBerry Explorer for Azure Blob Storage
ClumpsyLeaf CloudXplorer
Azure Storage Explorer from CodePlex (try version 4 beta)
There was an old program called Azure Blob Explorer or something that no longer works with the new Azure SDK.
Out of these, I personally like CloudBerry Explorer the best.
The easiest way is to use Azure Storage PowerShell. It provided many commands to manage your storage container/blob/table/queue.
For your mentioned case, you could use Set-AzureStorageBlobContent which could upload a local file into azure storage as a block blob or page blob.
Set-AzureStorageBlobContent -Container containerName -File .\filename -Blob blobname
For details, please refer to http://msdn.microsoft.com/en-us/library/dn408487.aspx.
If you're looking for a tool to do so, may I suggest that you take a look at our tool Cloud Storage Studio (http://www.cerebrata.com/Products/CloudStorageStudio). It's a commercial tool for managing Windows Azure Storage and Hosted Service. You can also find a comprehensive list of Windows Azure Storage Management tools here: http://blogs.msdn.com/b/windowsazurestorage/archive/2010/04/17/windows-azure-storage-explorers.aspx
Hope this helps.
The StorageClient has this built into it. No need to write really anything:
var account = new CloudStorageAccount(creds, false);
var client = account.CreateCloudBlobClient();
var blob = client.GetBlobReference("/somecontainer/hugefile.zip");
//1MB seems to be a pretty good all purpose size
client.WriteBlockSizeInBytes = 1024;
//this sets # of parallel uploads for blocks
client.ParallelOperationThreadCount = 4; //normally set to one per CPU core
//this will break blobs up automatically after this size
client.SingleBlobUploadThresholdInBytes = 4096;
blob.UploadFile("somehugefile.zip");
I use Cyberduck to manage my blob storage.
It is free and very easy to use. It works with other cloud storage solutions as well.
I recently found this one as well: CloudXplorer
Hope it helps.
There is a new OpenSource tool provided by Microsoft :
Project Deco - Crossplatform Microsoft Azure Storage Account Explorer.
Please, check those links:
Download binaries: http://storageexplorer.com/
Source Code: https://github.com/Azure/deco
You can use Cloud Combine for reliable and quick file upload to Azure blob storage.
A simple batch file using Microsoft's AzCopy utility will do the trick. You can drag-and-drop your files on the following batch file to upload into your blob storage container:
upload.bat
#ECHO OFF
SET BLOB_URL=https://<<<account name>>>.blob.core.windows.net/<<<container name>>>
SET BLOB_KEY=<<<your access key>>>
:AGAIN
IF "%~1" == "" GOTO DONE
AzCopy /Source:"%~d1%~p1" /Dest:%BLOB_URL% /DestKey:%BLOB_KEY% /Pattern:"%~n1%~x1" /destType:blob
SHIFT
GOTO AGAIN
:DONE
PAUSE
Note that the above technique only uploads one or more files individually (since the Pattern flag is specified) instead of uploading an entire directory.
You can upload files to Azure Storage Account Blob using Command Prompt.
Install Microsoft Azure Storage tools.
And then Upload it to your account blob will CLI command:
AzCopy /Source:"filepath" /Dest:bloburl /DestKey:accesskey /destType:blob
Hope it Helps.. :)
You can upload large files directly to the Azure Blob Storage directly using the HTTP PUT verb, the biggest file I have tried with the code below is 4,6 Gb. You can do this in C# like this:
// write up to ChunkSize of data to the web request
void WriteToStreamCallback(IAsyncResult asynchronousResult)
{
var webRequest = (HttpWebRequest)asynchronousResult.AsyncState;
var requestStream = webRequest.EndGetRequestStream(asynchronousResult);
var buffer = new Byte[4096];
int bytesRead;
var tempTotal = 0;
File.FileStream.Position = DataSent;
while ((bytesRead = File.FileStream.Read(buffer, 0, buffer.Length)) != 0
&& tempTotal + bytesRead < CHUNK_SIZE
&& !File.IsDeleted
&& File.State != Constants.FileStates.Error)
{
requestStream.Write(buffer, 0, bytesRead);
requestStream.Flush();
DataSent += bytesRead;
tempTotal += bytesRead;
File.UiDispatcher.BeginInvoke(OnProgressChanged);
}
requestStream.Close();
if (!AbortRequested) webRequest.BeginGetResponse(ReadHttpResponseCallback, webRequest);
}
void StartUpload()
{
var uriBuilder = new UriBuilder(UploadUrl);
if (UseBlocks)
{
// encode the block name and add it to the query string
CurrentBlockId = Convert.ToBase64String(Encoding.UTF8.GetBytes(Guid.NewGuid().ToString()));
uriBuilder.Query = uriBuilder.Query.TrimStart('?') + string.Format("&comp=block&blockid={0}", CurrentBlockId);
}
// with or without using blocks, we'll make a PUT request with the data
var webRequest = (HttpWebRequest)WebRequestCreator.ClientHttp.Create(uriBuilder.Uri);
webRequest.Method = "PUT";
webRequest.BeginGetRequestStream(WriteToStreamCallback, webRequest);
}
The UploadUrl is generated by Azure itself and contains a Shared Access Signature, this SAS URL says where the blob is to be uploaded to and how long time the security access (write access in your case) is given. You can generate a SAS URL like this:
readonly CloudBlobClient BlobClient;
readonly CloudBlobContainer BlobContainer;
public UploadService()
{
// Setup the connection to Windows Azure Storage
var storageAccount = CloudStorageAccount.FromConfigurationSetting("DataConnectionString");
BlobClient = storageAccount.CreateCloudBlobClient();
// Get and create the container
BlobContainer = BlobClient.GetContainerReference("publicfiles");
}
string JsonSerializeData(string url)
{
var serializer = new DataContractJsonSerializer(url.GetType());
var memoryStream = new MemoryStream();
serializer.WriteObject(memoryStream, url);
return Encoding.Default.GetString(memoryStream.ToArray());
}
public string GetUploadUrl()
{
var sasWithIdentifier = BlobContainer.GetSharedAccessSignature(new SharedAccessPolicy
{
Permissions = SharedAccessPermissions.Write,
SharedAccessExpiryTime =
DateTime.UtcNow.AddMinutes(60)
});
return JsonSerializeData(BlobContainer.Uri.AbsoluteUri + "/" + Guid.NewGuid() + sasWithIdentifier);
}
I also have a thread on the subject where you can find more information here How to upload huge files to the Azure blob from a web page
The new Azure Portal has an 'Editor' menu option in preview when in the container view. Allows you to upload a file directly to the container from the Portal UI
I've used all the tools mentioned in post, and all work moderately well with block blobs. My favorite however is BlobTransferUtility
By default BlobTransferUtility only does block blobs. However changing just 2 lines of code and you can upload page blobs as well. If you, like me, need to upload a virtual machine image it needs to be a page blob.
(for the difference please see this MSDN article.)
To upload page blobs just change lines 53 and 62 of BlobTransferHelper.cs from
new Microsoft.WindowsAzure.Storage.Blob.CloudBlockBlob
to
new Microsoft.WindowsAzure.Storage.Blob.CloudPageBlob
The only other thing to know about this app is to uncheck HELP when you first run the program to see the actual UI.
Check out this post Uploading to Azure Storage where it is explained how to easily upload any file via PowerShell to Azure Blob Storage.
You can use Azcopy tool to upload the required files to the azure default storage is block blob u can change pattern according to your requirement
Syntax
AzCopy /Source : /Destination /s
Try the Blob Service API
http://msdn.microsoft.com/en-us/library/dd135733.aspx
However, 400mb is a large file and I am not sure a single API call will deal with something of this size, you may need to split it and reconstruct using custom code.