character encoding - How to add a UTF-8 BOM in Java?

Question

I have a Java stored procedure which fetches record from the table using Resultset object and creates a CS Vfile.

BLOB retBLOB = BLOB.createTemporary(conn, true, BLOB.DURATION_SESSION);
retBLOB.open(BLOB.MODE_READWRITE);
OutputStream bOut = retBLOB.setBinaryStream(0L);

ZipOutputStream zipOut = new ZipOutputStream(bOut);
PrintStream out = new PrintStream(zipOut,false,"UTF-8");
out.write('ufeff');
out.flush();

zipOut.putNextEntry(new ZipEntry("filename.csv"));
while (rs.next()){
    out.print(""" + rs.getString(i) + """);
    out.print(",");
}
out.flush();

zipOut.closeEntry();
zipOut.close();
retBLOB.close();

return retBLOB;

But the generated CSV file doesn't show the correct German character. Oracle database also has a NLS_CHARACTERSET value of UTF8.

Please suggest.

Answer 1

BufferedWriter out = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(...), StandardCharsets.UTF_8));
out.write('ufeff');
out.write(...);

This correctly writes out 0xEF 0xBB 0xBF to the file, which is the UTF-8 representation of the BOM.