Interesting issue, especially for us germans!
What is about System.in, if one types some umlaute at Windows console?
Why are there theoretically different code pages for stdout and stderr?
-Ulf
Am 13.02.2012 18:36, schrieb Xueming Shen:
Hi
This is a long standing Windows codepage support issue on Java platform (we
probably have
20 bug/rfes filed for this particular issue and closed as the dup of 4153167).
Windows supports
two sets of codepages, ANSI (Windows) codepage and OEM (IBM) codepage.
Windows uses
ANSI/Windows codepage almost "everywhere" except in its dos/command prompt
window,
which uses OEM codepage. For example, on a normal English Windows, the default
Windows
codepage isCp1252 <http://msdn.microsoft.com/en-us/goglobal/cc305145> (west European Latin) and
the OEM codepage used in its dos/command
prompt however is Cp437 <http://msdn.microsoft.com/en-us/goglobal/cc305156> (you can use chcp
command to check/change the "active" codepage
used in your dos/coomand prompt). These two obviously have different mapping
for certain
code points, for example those umlaut characters.
J2SE runtime chooses the ANSI/Windows codepage as its default charset for its
i/o character
reading/writing, graphic text display, etc. including System.out&err. This
causes problem when
the ANSI code page and OEM codepage are not "compatible" and you happen to need
to write
those "in-compatible" characters to the dos/command prompt, as show in the
following test
case
String umlaut = "\u00f6\u00e4\u00fc\u00d6\u00c4\u00dc\u00df";
PrintWriter ps = new PrintWriter(new OutputStreamWriter(System.out,
"Cp437"), true );
ps.println("ps.cp437: " + umlaut);
System.out.println("sys.out : " + umlaut);
System.err.println("sys.err : " + umlaut);
You will see the umlauts get displayed correctly from PrintWriter with explicit
Cp437 encoding
setting, but garbled from system.out and err (because both the System.out & err
use the default
charset Cp1252, which is also used for all necessary Unicode <-> Windows
encoding conversion
for that particular vm instance).
For years, we have been debating whether or not we should and how to fix this
issue, do we
want to have two "default charset" for i/o. In jdk6, we have provided a
java.io.Console class
that specifically uses OEM codepage when running on Windows' dos/command prompt.
However, the feedback is that people still want the System.out/err to work
correctly with
the dos/command prompt, when the OEM codepage used is not "compatible" with the
default
Windows codepage.
The proposed change here is to use OEM codepage for System.out/err when the vm
is
started without its std out/err is redirected to something else, such as a file
(make sure
to only use OME for the dos/command prompt), if vm's std out/err is redirected,
then
continue to use the default charset (file.encoding) for the System.out/err. I
believe this
approach solves the problem without breaking any existing assumption/use
scenario.
The webrev is at
http://cr.openjdk.java.net/~sherman/4153167/webrev
Here is a simple"manual" test case.
public class HelloWorld {
public static void main(String[] args) throws Exception {
String umlaut = "\u00f6\u00e4\u00fc\u00d6\u00c4\u00dc\u00df";
System.out.println("file.encoding =" +
System.getProperty("file.encoding"));
System.out.println("stdout.encoding=" +
System.getProperty("sun.stdout.encoding"));
System.out.println("stderr.encoding=" +
System.getProperty("sun.stderr.encoding"));
System.out.println("-----------------------");
PrintWriter ps = new PrintWriter(new OutputStreamWriter(System.out,
"Cp437"),
true );
ps.println("ps.cp437: " + umlaut);
System.out.println("sys.out : " + umlaut);
System.err.println("sys.err : " + umlaut);
Console con = System.console();
if (con != null)
con.printf("console : %s%n", umlaut);
}
}
-Sherman
