Develop Reference

Creating QR Code as Base64 String using Spring Boot

I am creating a microservice using spring boot where in i have a file handling.
My task is to write the QR code to image file and base64 encode to transfer over network.
Because I need to write to an image file and then read and then base64 encode it , I need to first create the image file and then write to it.
Creating a temperory folder and keep the file ?, create a folder in root directory and keep the file? or use the java.io.tmpdir ....
Note: I have no use of this file once I encode it. Also there are lot of user to whom we will be exposing this service as rest api.
I want to know what is the best way to do this.

If you are using the https://github.com/zxing/zxing library i.e.
<dependency>
<groupId>com.google.zxing</groupId>
<artifactId>javase</artifactId>
<version>3.2.1</version>
</dependency>
Then something like the following will work.
#RestController
public class TestController {
#GetMapping(value = "/test")
public QrInfo getQrInfo() throws Exception {
String url = "https://news.bbc.co.uk";
int imageSize = 200;
BitMatrix matrix = new MultiFormatWriter().encode(url, BarcodeFormat.QR_CODE,
imageSize, imageSize);
ByteArrayOutputStream bos = new ByteArrayOutputStream();
MatrixToImageWriter.writeToStream(matrix, "png", bos);
String image = Base64.getEncoder().encodeToString(bos.toByteArray()); // base64 encode
// return QrInfo
QrInfo qrInfo = new QrInfo();
qrInfo.setUrl(url);
qrInfo.setImage(image);
return qrInfo;
}
}
#Data // lombok for brevity
class QrInfo {
private String url;
private String image;
}
NOTE: This approach doesn't write any files but does it all in-memory using a ByteArrayOutputStream .
If you hit this endpoint you'll see the following: -
{
"url": "https://news.bbc.co.uk",
"image": "iVBORw0KGgoAAAANSUhEUgAAAMgAAADIAQAAAACFI5MzAAABGUlEQVR42u2YSw7DIAxEzYpjcFM+N+UYrErtMUkjpd2WWQQlyudtLI89JpH5a8lDHvJnUkVXmkMPKcMeAg1peo70inrpRbm/ISFDwkhNX4NUSWxEo26WVFKisgc2ArWncSO3OthJvEs0nTju/bOT+NJKzJK++c5OovJWRIob2AwNsf6YXWJ3eFGbgXS4skgEGafaDGSifVONS/ZCQ/Q2YI5l8BdSS0ImwtTezehjiM9C3FG8fbVdykft/URTeEY918hlIZZFC9Yq0Rw6ns63nyxXtkTCYK6VuJv4NKvmMdgFMBHfBbRjb8JFxgoWW04RPmKfEaY2pgcZcT/OsL3GQ5baFrUN23iZZrvJ6pKjDJFXFvL8P3jIfvIGvNX7jsCaJvEAAAAASUVORK5CYII="
}
If you paste the Base64 into e.g https://codebeautify.org/base64-to-image-converter and point camera from your phone you will see the URL.
If you rendering this out it is easy i.e. in React (any JavaScript approach will be similar).
<img src={`data:image/png;base64,${image}`} />
I like this approach as if you are e.g. generate 2FA codes you can pass down both the random secret and the QR code - useful to have both as a backup if the user doesn't have access to a mobile device.

You can do this in a designated folder in your file-system easily and once you are done with the transfer, you can remove the file. But since, this operation is exposed over a rest api, concurrency and file collision can be an issue. To avoid that you can give unique to every file-name, that way same file-name collision can be avoided.
One approach could be to UUID for writing the file-name and storing the file with this name in the file-system. It will ensure collision doesn't occur.
String fileName = UUID.randomUUID().toString();

iText to remove Protected View from a PDF

I'm working on removing Protected View from a series of PDFs, and am trying to use the iText library within VBA. My main issue at this point is that I have no idea what method to use, and the iText documentation is pretty dense.
I'm also feeling my way forward on calling the iText library from VBA, so any help on syntax to do this is also appreciated, though I'm sure I could get there myself if I knew which method to call...
Currently, I've got:
Dim program As WshExec
program = Shell("Java.exe -jar " & mypath & "\itext-5.5.6\itextpdf-5.5.6.jar")
'Debug.print program returns a value here, so this line works.
'I'm thinking I need something like:
'Set program = RunProgram("Java.exe -jar " & mypath & "\itext-5.5.6\itextpdf-5.5.6.jar", & _
methodName, param1)
I've been using the following questions to get me this far...
Calling Java library (JAR) from VBA/VBScript/Visual Basic Classic
Microsoft Excel Macro to run Java program
Desired functionality is to have an unprotected PDF sitting in a folder on mypath.

The jar you are trying to run is not an executable jar. iText is a library that be used in a Java application by adding itextpdf-5.5.6.jar to the CLASSPATH. If you don't write any Java code, then the jar won't do a thing, hence your Shell() and your RunProgram() methods are useless: there is nothing to execute.
Moreover: from your question, it is far from certain that you have a Java environment on your machine. You are working in a VBA environment, which makes one wonder why you'd use the Java version of iText. Have you tried using iTextSharp, which is the .NET version of iText (written in C#)?
Take a look at this tutorial: Programmatically Complete PDF Form Fields using Visual Basic and the iTextSharp DLL
In this tutorial, we take an existing PDF, we fill out a form, and we get another PDF based on the original PDF, but with extra data. You can easily adapt the code so that it takes an existing PDF, doesn't add anything to the PDF, but saves the original PDF without its passwords, as is explained in my answer to How can I decrypt a PDF document with the owner password?
If you combine what you can learn from my Java code:
public void manipulatePdf(String src, String dest) throws IOException, DocumentException {
PdfReader.unethicalreading = true;
PdfReader reader = new PdfReader(src);
PdfStamper stamper = new PdfStamper(reader, new FileOutputStream(dest));
stamper.close();
reader.close();
}
with what you learn from the form filling tutorial, you get something like this (provided that you use the iTextSharp DLL instead of the iText jar):
Dim pdfTemplate As String = "c:\Temp\PDF\encrypted.pdf"
Dim newFile As String = "c:\Temp\PDF\decrypted.pdf"
PdfReader.unethicalreading = true
Dim pdfReader As New PdfReader(pdfTemplate)
Dim pdfStamper As New PdfStamper(pdfReader, New FileStream(
newFile, FileMode.Create))
pdfStamper.Close()
pdfReader.Close()
IMPORTANT: this will only remove the password if the file is only protected with an owner password (which is what I assume when you talk about protected view). If the file is protected in any other way, you'll have to clarify. Also note that the parameter unethicalreading is not without meaning: make sure that you're not doing unethical by removing the protection.

I was having to manipulate protected PDF files using iText.
I just put in my pom.xml the following dependency and nothing more.
<!-- https://mvnrepository.com/artifact/org.bouncycastle/bcprov-jdk15on -->
<dependency>
<groupId>org.bouncycastle</groupId>
<artifactId>bcprov-jdk15on</artifactId>
<version>1.59</version>
</dependency>

Enterprise Architect scripting with java - create and modify linked document

my question: How can I create a new linked document and insert (or connect) it into an element (in my case a Note-Element of an activity diagram).
The Element-Class supports the three Methods:
GetLinkedDocument ()
LoadLinkedDocument (string Filename)
SaveLinkedDocument (string Filename)
I missing a function like
CreateLinkedDocument (string Filename)
My goal: I create an activity diagram programmatically and some notes are to big to display it pretty in the activity diagram. So my goal is to put this text into an linked document instead of directly in the activity diagram.
Regards
EDIT
Thank you very much to Uffe for the solution of my problem. Here is my solution code:
public void addLinkedDocumentToElement(Element element, String noteText) {
String filePath = "C:\\rtfNote.rtf";
PrintWriter writer;
//create new file on the disk
writer = new PrintWriter(filePath, "UTF-8");
//convert string to ea-rtf format
String rtfText = repository.GetFormatFromField("RTF", noteText);
//write content to file
writer.write(rtfText);
writer.close();
//create linked document to element by loading the before created rtf file
element.LoadLinkedDocument(filePath);
element.Update();
}
EDIT EDIT
It is also possible to work with a temporary file:
File f = File.createTempFile("rtfdoc", ".rtf");
FileOutputStream fos = new FileOutputStream(f);
String rtfText = repository.GetFormatFromField("RTF", noteText);
fos.write(rtfText.getBytes());
fos.flush();
fos.close();
element.LoadLinkedDocument(f.getAbsolutePath());
element.Update();

First up, let's separate the linked document, which is stored in the EA project and displayed in EA's built-in RTF viewer, from an RTF file, which is stored on disk.
Element.LoadLinkedDocument() is the only way to create a linked document. It reads an RTF file and stores its contents as the element's linked document. An element can only have one linked document, and I think it is overwritten if the method is called again but I'm not absolutely sure (you could get an error instead, but the EA API tends not to work that way).
In order to specify the contents of your linked document, you must create the file and then load it. The only other way would be to go hacking around in EA's internal and undocumented database, which people sometimes do but which I strongly advise against.
In .NET you can create RTF documents using Microsoft's Word API, but to my knowledge there is no corresponding API for Java. A quick search turns up jRTF, an open-source RTF library for Java. I haven't tested it but it looks as if it'll do the trick.
You can also use EA's API to create RTF data. You would then create your intended content in EA's internal display format and use Repository.GetFormatFromField() to convert it to RTF, which you would then save in the file.
If you need to, you can use Repository.GetFieldFromFormat() to convert plain-text or HTML-formatted text to EA's internal format.

how to Show or Read docx file

I am new to rendering files in android, and I want to render or display a docx file in my application.
I had already extract text from docx file, but now I want to extract images from the docx file as well.
I've found several ways to display images in pure Java, but are there any good examples for Android?
I tried this code to fetch Images but not working...
public void extractImages(Document xmlDoc)
{
NodeList binDataList = xmlDoc.getElementsByTagName("w:drawings");
String fileName = "";
Node currentNode;
for(int i = 0; i < binDataList.getLength(); i++)
{
currentNode = binDataList.item(i);
if(currentNode.getNodeType() == Node.ELEMENT_NODE && ((Element)currentNode).hasAttribute("w:name"))
{
File newImageFile = new File(picDirectory, ((Element)currentNode).getAttribute("w:name").replaceFirst("wordml://", ""));
if(newImageFile.exists())
{
}
else
{
if(writeImage(newImageFile, currentNode))
{
//Print some success message
}
}
}
}

Have a look at AndroidDocxToHtml, which I made to demonstrate using docx4j on Android.
A couple of caveats.
First, that project does not include all docx4j dependencies, only the ones required for docx to HTML conversion. So if you want to do other things, you may need others of the dependencies.
Second, docx4j requires JAXB - see this blog post re JAXB on Android - and JAXB context init on app startup takes a while depending on the device. There are ways to work around this, but at extra effort.
If all you want to do is extract the images, and you don't care how they relate to the text, you could just look for image parts. You might use OpenXML4J for that, and avoid JAXB.

The easiest way to create an image in Android is to use the BitmapFactory factory methods.
The BitmapFactory class has methods for creating a Bitmap from a byte array, a file or an InputStream.
Once you have a Bitmap object you can display it by setting it on an ImageView in your layout using the setImageBitmap method.

You can just unzip the file (rename to .zip and open it) then you can investigate the folder structure, where the images are located etc.

Java/ImageIO Validate format before reading the entire file?

I'm developing a Web application that will let users upload images.
My concern is the file´s size, specially if they are invalid formats.
I'm wondering if there´s a way in java (or a third party library) to check the allowed files formats (jpg, gif and png) before reading the entire file.

If you wish to support only a few types of images you can start by (up)loading the image and at some point use the first few bytes to check wether you wish to continue the upload.
Quite a lot of image formats can be recognized by the first few bytes, the magic number. If the number matches you don't know whether the file is valid of course, but it may be used to match extension and magic number to prevent is really does not correspond at all.
Have a look at this page to check out some Java which checks mime-types. Do read the docs or source to check whether any given method requires the entire file, or can operate on the first few bytes. I've not used those libraries :)
Also check out this page which also lists some java libraries, and some papers on which detection is based.
Don't forget to put in some feedback if you managed to find something you like!

You don't need 3rd party libraries. The code you have to write is simple.
At the point you are handling your uploads, filter the files by their extension. This isn't perfect, but will account for most of the cases.
However, this would mean files are already uploaded to the server. You can use a bit of javascript on the client-side to perform the same operation - check whether the value of the file-upload component contains an allowed file type - .jpg, .png, etc.

function extensionsOkay(fval) {
var extension = new Array();
extension[0] = ".png";
extension[1] = ".gif";
extension[2] = ".jpg";
extension[3] = ".jpeg";
extension[4] = ".bmp";
// No other customization needed.
var thisext = fval.substr(fval.lastIndexOf('.')).toLowerCase();
for(var i = 0; i < extension.length; i++) {
if(thisext == extension[i]) {
$('#support-documents').hide();
return true; }
}
// show client side error message
$('#span.failed').show();
return false;
}