Added log4j support to the log wrapper. It is enabled if the log4j

configuration system property is set (and a particular logger is not
specifically configured).


git-svn-id: https://samskivert.googlecode.com/svn/trunk@2315 6335cc39-0255-0410-8fd6-9bcaacd3b74c

build.xml

@@ -69,6 +69,7 @@
       <exclude name="com/samskivert/test/**" unless="build.test"/>
       <exclude name="com/samskivert/util/**" unless="build.util"/>
       <exclude name="com/samskivert/util/FileUtil*" unless="build.fileutil"/>
+      <exclude name="com/samskivert/util/Log4JLogger*" unless="log4j.present"/>
       <exclude name="com/samskivert/velocity/**" unless="build.velocity"/>
       <exclude name="com/samskivert/xml/**" unless="build.xml"/>
       <exclude name="com/samskivert/**/tests/**" unless="build.tests"/>

etc/depends-incl.xml

@@ -70,6 +70,10 @@
     <available property="junit.present" classpathref="classpath"
      classname="junit.framework.Test"/>
     <echo level="info">JUnit: ${junit.present}</echo>
+
+    <available property="log4j.present" classpathref="classpath"
+     classname="org.apache.log4j.Logger"/>
+    <echo level="info">log4j: ${log4j.present}</echo>
   </target>
 
   <!-- combines package availability into build controls -->

etc/libs-incl.xml

@@ -10,6 +10,7 @@
     <include name="ehcache-1.2.jar"/>
     <include name="junit-3.7.jar"/>
     <include name="junit4.jar"/>
+    <include name="log4j.jar"/>
     <include name="mail.jar"/>
     <include name="servlet-api.jar"/>
     <include name="velocity-1.5-dev.jar"/>

src/java/com/samskivert/util/Log4JLogger.java

@@ -0,0 +1,88 @@
+//
+// $Id$
+//
+// samskivert library - useful routines for java programs
+// Copyright (C) 2001-2008 Michael Bayne
+// 
+// This library is free software; you can redistribute it and/or modify it
+// under the terms of the GNU Lesser General Public License as published
+// by the Free Software Foundation; either version 2.1 of the License, or
+// (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+package com.samskivert.util;
+
+import org.apache.log4j.Level;
+
+/**
+ * A factory for creating log4j logger implementations.
+ */
+public class Log4JLogger implements Logger.Factory
+{
+    // from interface Logger.Factory
+    public void init ()
+    {
+    }
+
+    // from interface Logger.Factory
+    public Logger getLogger (String name)
+    {
+        return new Impl(org.apache.log4j.Logger.getLogger(name));
+    }
+
+    // from interface Logger.Factory
+    public Logger getLogger (Class clazz)
+    {
+        return getLogger(clazz.getName());
+    }
+
+    protected static class Impl extends Logger
+    {
+        public Impl (org.apache.log4j.Logger impl)
+        {
+            _impl = impl;
+        }
+
+        @Override // from Logger
+        public void debug (Object message, Object... args)
+        {
+            if (_impl.isEnabledFor(Level.DEBUG)) {
+                _impl.log(Level.DEBUG, format(message, args), getException(message, args));
+            }
+        }
+
+        @Override // from Logger
+        public void info (Object message, Object... args)
+        {
+            if (_impl.isEnabledFor(Level.INFO)) {
+                _impl.log(Level.INFO, format(message, args), getException(message, args));
+            }
+        }
+
+        @Override // from Logger
+        public void warning (Object message, Object... args)
+        {
+            if (_impl.isEnabledFor(Level.WARN)) {
+                _impl.log(Level.WARN, format(message, args), getException(message, args));
+            }
+        }
+
+        @Override // from Logger
+        public void error (Object message, Object... args)
+        {
+            if (_impl.isEnabledFor(Level.ERROR)) {
+                _impl.log(Level.ERROR, format(message, args), getException(message, args));
+            }
+        }
+
+        protected org.apache.log4j.Logger _impl;
+    }
+}

src/java/com/samskivert/util/Logger.java

@@ -135,7 +135,16 @@ public abstract class Logger
         // if a custom class was specified as a system property, use that
         _factory = createConfiguredFactory();
 
-        // TODO: create and try a log4j logger
+        // create and a log4j logger if the log4j configuration system property is set
+        try {
+            if (_factory == null && System.getProperty("log4j.configuration") != null) {
+                _factory = (Factory)Class.forName("com.samskivert.util.Log4JLogger").newInstance();
+            }
+        } catch (SecurityException se) {
+            // in a sandbox, no biggie
+        } catch (Throwable t) {
+            System.err.println("Unable to instantiate Log4JLogger: " + t);
+        }
 
         // lastly, fall back to the Java logging system
         if (_factory == null) {