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How can I write PDF from BLOB object?

 
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I would like to write PDF file from SQL BLOB object. I created the code below based on:
https://coderanch.com/t/615356/databases/store-PDF-Word-BLOB-column
https://stackoverflow.com/questions/28220352/how-to-convert-a-blob-object-into-a-pdf-file-in-java



It creates a PDF but when I tried to open the PDF I got the message: format error: not a PDF or corrupted

Could someone let me know what I did wrong?

 
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You store PDFs in a table called IMAGES in a column called Image? Highly confusing.

Why are you treating the data differently based on the filename for the target file? Presumably all data from the DB should be stored in the file, yes?

Have you tried something like this?
 
Beata Szabo-Takacs
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Dear Tim,

The name of the BLOB column in SQL is "IMAGE" and the Table name is "IMAGES" because some .png images are stored as a binary large object.
I tried to create PDF in the same way as you suggested. I just commented out the "For PDF writing" part because the part of the code after "else" is the same as
you suggested. It creates PDF but when I open it I got the same format error.  
 
Tim Moores
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Just to make sure: those blobs are in fact PDFs, not images? How are they being stored?
 
Beata Szabo-Takacs
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Dear Tim,

I uploaded .png images to MySQL as longblob and I would like to download them as pdf. My aim is to convert the .png images to pdf.
 
Tim Moores
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You can't convert between file formats by changing the file extensions. You need to use a library that can create PDFs, like PDFBox. There is an example of how to create a PDF with an image on this site: https://coderanch.com/wiki/659953/PDFBox
 
Beata Szabo-Takacs
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Thank you very much Tim for your suggestion! I accepted. I could solve the issue with the following code:


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