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.

Answer 2

Just in case people are using PrintStreams, you need to do it a little differently. While a Writer will do some magic to convert a single byte into 3 bytes, a PrintStream requires all 3 bytes of the UTF-8 BOM individually:

    // Print utf-8 BOM     PrintStream out = System.out;     out.write('\ufeef'); // emits 0xef     out.write('\ufebb'); // emits 0xbb     out.write('\ufebf'); // emits 0xbf 

Alternatively, you can use the hex values for those directly:

    PrintStream out = System.out;     out.write(0xef); // emits 0xef     out.write(0xbb); // emits 0xbb     out.write(0xbf); // emits 0xbf