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How do I extract a BLOB from a database?

A BLOB (Binary Large OBject) is essentially an array of bytes (byte[]), stored in the database. You

extract the data in two steps:

1. Call the getBlob method of the Statement class to retrieve a java.sql.Blob object

2. Call either getBinaryStream or getBytes in the extracted Blob object to retrieve the java byte[] which

is the Blob object.

Note that a Blob is essentially a pointer to a byte array (called LOCATOR in database-talk), so the

java.sql.Blob object essentially wraps a byte pointer. Thus, you must extract all data from the database

blob before calling commit or

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private void runGetBLOB()

{ try

{ // Prepare a Statement:

PreparedStatement stmnt = conn.prepareStatement("select aBlob from BlobTable");

// Execute

ResultSet rs = stmnt.executeQuery();


{ try

{ // Get as a BLOB

Blob aBlob = rs.getBlob(1);

byte[] allBytesInBlob = aBlob.getBytes(1, (int) aBlob.length());

} catch(Exception ex)

{ // The driver could not handle this as a


// Fallback to default (and slower) byte[] handling

byte[] bytes = rs.getBytes(1);


// Close resources



} catch(Exception ex)

{ this.log("Error when trying to read BLOB: "





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