How to write PNG image file from BLOB?

Question

I got this code to create and write a file from Oracle BLOB to PNG image file

try {
    final File file = new File("C:/Users/John.Doe/Desktop/PDF Templates/POC/output/" + pdfObject.getFileName());
    final FileWriter fileWriter = new FileWriter(file);

    fileWriter.write(pdfObject.getContent());  << a String of the PNG content, see below:
    fileWriter.flush();
    fileWriter.close();
} catch (final IOException e) {
    e.printStackTrace();
}

PNG File content:

�PNG

IHDR<binary code> .....

After i'm running this code, the image is not created well, means that, when i'm trying to open it using Microsoft Photos it says: "It looks like we don't support this file format"

Also, the original file size is less then the new one that being created with the code above.

What i'm doing wrong here ?

Possible duplicate of [Java BLOB to image file](https://stackoverflow.com/questions/50427495/java-blob-to-image-file) — fantaghirocco, Dec 13 '18 at 13:39
To write binary data you would use a Stream, not a Writer. The latter is for character data. Also, what's the type of `pdfObject.getContent()`? — Henry, Dec 13 '18 at 13:42
@roeygol maybe `pdfObject.getContent()` is the base64 encoding of the image bytes — fantaghirocco, Dec 13 '18 at 13:45
@roeygol can you provide a link to your file so when can see exactly what you have? — jhenrique, Dec 15 '18 at 05:29

score 1 · Answer 1 · answered Dec 13 '18 at 13:44

1

A png image is not human readable text, and it gets corrupted if you try to represent it as a string and use FileWriter.

Instead your should get the content of the blob as an array of bytes or as an InputStream, and use FileOutputStream to write it to a file.

answered Dec 13 '18 at 13:44

Joni

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for more detailed help you should update the question with the exact type of `pdfObject`. Clearly it's not [java.sql.Blob](https://docs.oracle.com/javase/7/docs/api/java/sql/Blob.html) because it has this "getContent" method. – Joni Dec 13 '18 at 18:21

How to write PNG image file from BLOB?

1 Answers1