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Android webview - how to fetch a file from external storage

I have a mobile app that wraps around the web-app, using webview.
The web-app has a button to open a large .zip file (e.g. 100 MB).
The user clicks a button, and selects a .zip file.
This triggers an onChange function with a variable of type File (Blob), which includes attributes like:
file name
file size
file type (application/zip)
The javascript code then parses the .zip file, extracts specific data within it and uses it within the web-app.
This works well within the web-app, when the app is called via the Chrome browser.
For example when operated in chrome browser on an Android phone, I can pull the .zip file and open it in the web-app.
I want to do the same but using the mobile app.
I am able to pick up the .zip file using a File Chooser, and pass it to Webview but I have problems to fetch the file from the Javascript code.
For reference, I am able to pass an image, by creating a data_uri using stringBuilder and passing the content (as data:image/jpeg;base64).
But the zip file is much larger.
When calling fetch(fileUri) from the Javascript side I'm getting errors.
I'm using the following uri
/storage/emulated/0/Android/data/com.example/files/Download/file2.zip
The fetch succeeds but returns a blob with size of 165 (i.e. not the actual size of the file) which hosts the error message:
{
"error": "Not Found",
"message": "The requested URL was not found on the server. If you entered the URL manually please check your spelling and try again."
}
The program flow is like so:
I select a .zip file via FileChooser.
In onActivityResult, the uri value is /document/msf:12858 (seen via uri = intent.getData();)
The uri needs to be mapped into a real path file url, such that the fileUrl will be passed to webview.
Webview will then fetch the file using the fileUrl.
I searched how to get the real path file url when selecting a file with FileChooser, and found
this, and this links.
I wasn't able to get the real file path, so I decided to read the file and write it to another location, so I can get a file path. (this is not efficient and done just to check the functionality).
I create the new file using the following code:
InputStream stream = context.getContentResolver().openInputStream(uri);
File file2 = new File(context.getExternalFilesDir(Environment.DIRECTORY_DOWNLOADS), "file2.zip");
writeBytesToFile(stream, file2);
I don't see any errors when creating the file, and when creating the file, the number of bytes that are read and written to the new file are as expected.
For file2, I get a value of:
/storage/emulated/0/Android/data/com.example/files/Download/file2.zip
Then, within the Javascript code I fetch this file path.
But I'm getting a Blob with the "file-not-found" content as above.
So:
How can I verify that the file is indeed created and that the path can be fetched from webview?
How can I get the real file path of the original selected file, so I don't have to read and write the original file to new location just to get the file path?
Thanks

I was able to get the file from external storage by doing the following steps:
create an initial uri (uri1)
The uri is created by:
creating a temporary file (file1) in the storage dir via
context.getExternalFilesDir(Environment.DIRECTORY_DOWNLOADS)
I'm not sure why a temporary file need to be created but if I don't create a file I cannot get the uri.
createFile3
get the uri via
Uri uri1 = FileProvider.getUriForFile(context, "com.example.android.fileprovider", file1);
create an intent with the following attributes:
Intent.ACTION_OPEN_DOCUMENT
category: Intent.CATEGORY_OPENABLE
type: "application/zip"
extra attribute: fileIntent.putExtra(DocumentsContract.EXTRA_INITIAL_URI, uri1);
this opens a dialog box for selecting openable zip files in the Downloads directory,
after the file is selected, a new uri (uri2) is created that includes the name of the selected file.
extract the name of the file via
String fileName = getFileName(context, uri2);
create the dirPath by appending the filename
dirPath = "/data/user/0/com.example/" + fileName;
if the dirPath does not exist (first time), write the file to its dirPath location.
on successive ocassions dirPath exists, so there is no need to re-write the file.
open the file with regular Java means, e.g. via
ZipFile zip = new ZipFile(dirPath);

Mirth connect javascript reader

I am using mirth connect 3.0.3 on windows.my requirement is I have a text file in D drive with some name and id as the text I need to pick that file using mirth javascript reader and insert into the database can u please help me to pick the file using javascript reader.
I tried it by using java code and converting that into to .jar file and placed it in the custom-lib folder in mirth connect and importing that in a script but I want to do it without .jar file
I am getting stuck in importing the packages can you help me to pick the file using javascript reader.

You can take two aproaches:
Use a File Reader source insted of JavaScript Reader source, then modify the transformer adding a new step in which insert your file's content into your database.
Use the FileUtil.read method to read file content inside your Javascript Reader source:
var fileData = FileUtil.read('D:\my_awesome_folder\data.txt');
//Do something with fileData

How to load the contents of a local text file by name using Javascript and HTML 5?

Working in Chrome, loading a local html or JS file.
I found many examples of how to load a file that is selected using the Choose File input.
However, didn't figure out how to do it given a file name without using the Choose File input.
The Choose File input returns a File object.
How to create the File object without the Choose File input?
From the File API:
new File(
Array parts,
String filename,
BlobPropertyBag properties
);
But didn't figure out what the parts and properties would be.
Edit: Use case:
I have code coverage results generated as part of a test suite. It is stored as JSON (which is easy to read), but I need to display it with the source code.
So the feature is to load the source code and JSON data, and render them together on a web page using HTML and Javascript.
The file would be opened from the browser and lives on the local machine. There is no server.

The browser cannot load arbitrary files by name from your filesystem without special extensions or other shenanigans. This is a security policy to prevent random web sites from reading files from your hard disk as you browse the internet.
If you're down to do something special like if you want to write a chrome app, you could get access to some nice APIs for accessing the filesystem:
https://developer.chrome.com/apps/fileSystem

The File constructor doesn't read a file from the harddrive, but rater make a virtual file, consider this:
var file = new File(["some", "content"], "/tmp/my-name.txt");
var reader = new FileReader();
reader.onload = function() {
console.log(reader.result); // somecontent
};
No file will be read or stored on the clients machine.
If you are talking about creating files in nodejs then you should take a look at fs.

For security reasons all browsers don't support predefined values on file fields so the answer is you can't.

File Size and Format before uploading

Is there any way to check for file format and size of the file before uploading it in javascript?

No, that's not possible. You can check for the extension but still it could be wrong because a text file renamed to zip will show you zip as an extension. You need server-side script for that.
Once file is uploaded, you can check its mime-type and size with server-side script.

Assuming you've obtained the fileTobeUploaded object (i don't know how you are doing the upload), with the following you could get the size in bytes.
var reader = new FileReader();
reader.onload = (function(theFile) {
alert(theFile.size);
})(fileTobeUploaded);

I believe you can retrieve size information about the file using FLASH, however to determine the file format, you will most probably need to rely on the file extension... and that's a weak determination with regards to security (malware etc.)

How to open a text file using Javascript from Adobe Indesign CS4?

How can I open a text file, read the contents, and then insert the contents into a document in InDesign?

Here's an example of reading a file from InDesign. If you want to write to a file as well, you will need to open the file in write mode w instead.
// Choose the file from a dialog
var file = File.openDialog();
// Or use a hard coded path to the file
// var file = File("~/Desktop/hello world.txt");
// Open the file for reading
file.open("r");
// Get the first text frame of the currently active document
var doc = app.activeDocument;
var firstTextframe = doc.pages[0].textFrames[0];
// Add the contents of the file to the text frame
firstTextframe.contents += file.read();
Here is a link to the File object's documentation online. You can also find the rest of InDesign's scripting DOM documentation here.

This is the pdf for InDesign JavaScript scripting. There's a few mentions of a File object in there, but it's not documented.
http://www.adobe.com/products/indesign/scripting/pdfs/InDesignCS4_ScriptingGuide_JS.pdf
That's because the core utilities for all CS5 products are documented here
https://www.adobe.com/content/dam/Adobe/en/devnet/indesign/cs55-docs/InDesignScripting/InDesign-ScriptingTutorial.pdf
or the general documentation:
http://www.adobe.com/content/dam/Adobe/en/devnet/scripting/pdfs/javascript_tools_guide.pdf
Look for: File System Access

Thanks for the pointer to the various PDFs.
The response to this question is in the execute() command.
fileObj.execute()

Javascript does not allow access to your computer's operating system, files or directories for security reasons, therefore there is no way to access the text file directly using Javascript.
Usually a server-side technology such as PHP, Adobe Coldfusion, Java or .NET (for example) is used to upload the file via a HTML form submission, read it and do whatever it needs to do.
I hope that helps.