如何在java中添加UTF-8 BOM

Question

我有一个Java存储过程,它使用Resultset对象从表中获取记录并创建一个csv文件.

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;

但生成的csv文件未显示正确的德语字符.Oracle数据库的NLS_CHARACTERSET值也为UTF8.

请建议.

Answer 1

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

这正确地将0xEF 0xBB 0xBF写入文件,这是BOM的UTF-8表示.

Answer 2

要以UTF-8编写BOM,您需要PrintStream.print(),而不是PrintStream.write().

此外,如果您想在csv文件中包含BOM ,我猜您需要在之后打印BOM putNextEntry().

Answer 3

万一人都使用PrintStreamS,你需要以不同的方式做到这一点.虽然Writer将一个字节转换为3个字节会产生一些魔力,但是PrintStream需要单独使用UTF-8 BOM的所有3个字节:

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

或者,您可以直接使用十六进制值:

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

Answer 4

我认为那out.write('\ufeff');应该是out.print('\ufeff');.

根据javadoc,该write(int)方法实际上写了一个字节...没有任何字符编码.所以out.write('\ufeff');写字节0xff.相反,该print(char)方法使用流的编码将字符编码为一个或多个字节,然后写入这些字节.

Answer 5

您将其添加到第一个 CSV 字符串

String CSV = "";
byte[] BOM = {(byte) 0xEF,(byte) 0xBB,(byte) 0xBF};
CSV = new String(BOM) + CSV;

这对我有用。