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Subject: RE: commons logging class level logging
Date: Tue, 29 Mar 2005 12:09:43 -0500
Message-ID: <4876153C00898F43B189AF95F84BCE148E23EE@usilms28.ca.com>
Thread-Topic: commons logging class level logging
Thread-Index: AcU0gIok1n8fxPaUQRKJ5YMxwily2QAAHHRg
From: "Scovetta, Michael V" <Michael.Scovetta@ca.com>
To: "Jakarta Commons Users List" <commons-user@jakarta.apache.org>

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Trenton,

I'm working on project to do add method-level authorization to Java
(actually, it's just a simple class, but it's pretty cool)-- Anyway, at
the heart of it is a method:

Play with it a little, I believe if you have

public class Foo {
  public static void main(String[] args) {
    System.out.println(getCurrentMethodName(1));
  }
}
You get "Foo.main:3"

If you have:
public class Foo {
  public static void main(String[] args) {
    bar();
  }
  public static void bar() {
    System.out.println(getCurrentMethodName(2));
  }
}
You also get "Foo.main:3" (since it back-tracked 2 method calls)

It's rough, but I think this'll work for ya. I've attached the source
code for the CallerUtils project, it's not complete yet, but it's a
start.


/**
 * Underlying method to get the calling method's name.
 * @param extra number of extra callees to go back
 * @return method name, package.class.method:line
 */
public static String getCurrentMethodName(int extra) {
    try {
        ByteArrayOutputStream baos =3D new ByteArrayOutputStream();
        PrintWriter pw =3D new PrintWriter(baos);
        (new Throwable()).printStackTrace(pw);
        pw.flush();
        String stackTrace =3D baos.toString();
        pw.close();

        StringTokenizer tok =3D new StringTokenizer(stackTrace, "\n");
        String l =3D tok.nextToken(); // 'java.lang.Throwable'
        l =3D tok.nextToken(); // 'at ...getCurrentMethodName'
        for (int i =3D 0; i < extra; i++) {
            l =3D tok.nextToken(); // 'at ...timestampProfiler or
others...
        }
        l =3D tok.nextToken(); // 'at ...<caller to getCurrentRoutine>'
        // Parse line 3
        tok =3D new StringTokenizer(l.trim(), " <(");
        String t =3D tok.nextToken(); // 'at'
        t =3D tok.nextToken(); // '...<caller to getCurrentRoutine>'
        String line =3D tok.nextToken();
        int colon =3D line.indexOf(":");
        if (colon !=3D -1) {
            int paren =3D line.indexOf(")", colon);
            line =3D line.substring(colon + 1, paren);
            return t + ":" + line;
        } else {
            return t;
        }
    } catch (Exception ex) {
        return "Unknown method.";
    }
}

Michael Scovetta
Computer Associates
Senior Application Developer


-----Original Message-----
From: Trenton D. Adams [mailto:trenta@athabascau.ca]=20
Sent: Tuesday, March 29, 2005 11:58 AM
To: Jakarta Commons Users List
Subject: Re: commons logging class level logging

Ok, this is slightly off topic for this list then.  But I'd appreciate=20
any help.

What's the quickest and easiest way of my code knowing what class called

a method?  The reason I ask is because we have some wrapper methods in=20
our main class that every other class calls to do logging.  I would like

that method to be able to determine what class it was that called, so=20
that I could use the proper logger/category.

Also, for log4j, is Logger.getLogger("classname") an efficient way of=20
getting a logger for each class?  e.g. should I be calling this method=20
every time my *wrapper* log method is called?  How does the commons=20
logging do this properly, surely it has to do something similar since=20
it's a wrapper too?

Simon Kitching wrote:
> Trenton D. Adams <trenta <at> athabascau.ca> writes:
>=20
>=20
>>I thought I read somewhere that JCL allows one to turn on/off debug=20
>>logging based on the package or class name.  Is that right?  I'm
looking=20
>>on the JCL website, but can't find information on that.  Perhaps
that's=20
>>because I don't know what to search for!
>>
>=20
>=20
> JCL is simply a "wrapper" that provides a common API to a number of
different=20
> logging libraries. Configuration of the underlying library is
explicitly *not*=20
> part of JCL.
>=20
> So if you are using log4j as the underlying library then you need to
read up on=20
> how to configure log4j to turn on/off logging by category name. If you
are=20
> using native jdk-1.4 logging as the underlying logging library then
you need to=20
> read up on configuring that, etc.
>=20
> Both of the above logging systems *do* have the ability to filter log
messages=20
> based on log category name (and the recommended convention is for code
to use=20
> the current class name as the log category).
>=20
> Regards,
>=20
> Simon
>=20
>=20
>=20
>=20
>=20
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: commons-user-unsubscribe@jakarta.apache.org
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>=20


--=20
Trenton D. Adams
Web Programmer Analyst
Navy Penguins at your service!
Athabasca University
(780) 675-6195
:wq!

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