Comment puis-je convertir un fichier PNG en PDF à l'aide de java?

Un exemple qui tourne la page, si le mode paysage correspond le mieux à

/**
* Converts arbitrary image file to PDF
* http://stackoverflow.com/a/42937466/241986
* @param imageFile contents of JPEG or PNG file
* @param outputStream stream to write out pdf, always closed after this method execution.
* @throws IOException when there' an actual exception or image is not valid
*/
public static void imageToPdf(byte[] imageFile, OutputStream outputStream) throws IOException {
try {
Image image;
try {
image = Image.getInstance(imageFile);
} catch (BadElementException bee) {
throw new IOException(bee);
}
//See http://stackoverflow.com/questions/1373035/how-do-i-scale-one-rectangle-to-the-maximum-size-possible-within-another-rectang
Rectangle A4 = PageSize.A4;
float scalePortrait = Math.min(A4.getWidth() / image.getWidth(),
A4.getHeight() / image.getHeight());
float scaleLandscape = Math.min(A4.getHeight() / image.getWidth(),
A4.getWidth() / image.getHeight());
//We try to occupy as much space as possible
//Sportrait = (w*scalePortrait) * (h*scalePortrait)
//Slandscape = (w*scaleLandscape) * (h*scaleLandscape)
//therefore the bigger area is where we have bigger scale
boolean isLandscape = scaleLandscape > scalePortrait;
float w;
float h;
if (isLandscape) {
A4 = A4.rotate();
w = image.getWidth() * scaleLandscape;
h = image.getHeight() * scaleLandscape;
} else {
w = image.getWidth() * scalePortrait;
h = image.getHeight() * scalePortrait;
}
Document document = new Document(A4, 10, 10, 10, 10);
try {
PdfWriter.getInstance(document, outputStream);
} catch (DocumentException e) {
throw new IOException(e);
}
document.open();
try {
image.scaleAbsolute(w, h);
float posH = (A4.getHeight() - h) / 2;
float posW = (A4.getWidth() - w) / 2;
image.setAbsolutePosition(posW, posH);
image.setBorder(Image.NO_BORDER);
image.setBorderWidth(0);
try {
document.newPage();
document.add(image);
} catch (DocumentException de) {
throw new IOException(de);
}
} finally {
document.close();
}
} finally {
outputStream.close();
}
}

À l'intérieur pom.xml, l'un des gratuit iText fourches, si vous n'êtes pas déjà en utilisant la bibliothèque iText

<dependency>
<groupId>com.github.librepdf</groupId>
<artifactId>openpdf</artifactId>
<version>1.0.1</version>
</dependency>

OriginalL'auteur Boris Treukhov