On 9/15/16 8:56 AM, Aleksey Shipilev wrote:
On 09/15/2016 09:06 AM, Xueming Shen wrote:
Console is supposed to be a "char/String" based class, "encoding"
really should have no business here in its api. Simply for some
implementation convenience is really not a good reason to add such a
public method.
Let's look at it this way: there is a problem with console encoding that
Console class solves, nicely abstracting the subtleties away. In doing
so, it polls GetConsoleCP, the WinAPI call:
What I meant is that the Console was/is designed the way that the user
can access
the console/terminal without knowing/dealing with the "encoding". The
encoding
concept is purposely hidden from the very beginning, with the
assumption/believe
that this is a implementation detail you really don't need to know when
using the
Console class in general use scenario. It's obviously it would be
helpful and convenient
if this encoding info can be accessed in your use case, but given this
is really not a
"normal" use scenario, what I'm saying is the System properties might be
better place
for such information. Seems like the jmh.util.Utils is accessing the
System.properties
already for other system/vm-wide info, such as the vm version, os.name
...as well
as the file.encoding you might need for non-console in/output.
Sherman
JNIEXPORT jstring JNICALL
Java_java_io_Console_encoding(JNIEnv *env, jclass cls)
{
char buf[64];
int cp = GetConsoleCP();
if (cp >= 874 && cp <= 950)
sprintf(buf, "ms%d", cp);
else
sprintf(buf, "cp%d", cp);
return JNU_NewStringPlatform(env, buf);
}
If by "convenience" you mean avoiding doing the JNI call that polls that
OS-specific bit of data, then yes, APIs provide lots of those conveniences.
That said, I would be fine to have such informative info in the
system properties, together with its siblings, file,encoding and
another "supposed to be private" property sun.jnu.encoding.
Actually, if you look into the launcher, it does:
static char* getConsoleEncoding()
{
char* buf = malloc(16);
int cp;
if (buf == NULL) {
return NULL;
}
cp = GetConsoleCP();
if (cp >= 874 && cp <= 950)
sprintf(buf, "ms%d", cp);
else
sprintf(buf, "cp%d", cp);
return buf;
}
...
sprops.sun_stdout_encoding = getConsoleEncoding();
...which opens a way to poll this without a Reflection hack. Extended
the JMH hack with it, but it still fragile:
http://hg.openjdk.java.net/code-tools/jmh/rev/8c20adb08b2d
Thanks,
-Aleksey
