svn commit: rev 21209 - excalibur/trunk/logger/src/java/org/apache/avalon/excalibur/logger/log4j

[cz...@apache.org]

Author: cziegeler
Date: Mon Jun 14 07:23:58 2004
New Revision: 21209

Added:
   excalibur/trunk/logger/src/java/org/apache/avalon/excalibur/logger/log4j/Log4JConfigurator.java
Log:
Add context values for property expansion

Added: excalibur/trunk/logger/src/java/org/apache/avalon/excalibur/logger/log4j/Log4JConfigurator.java
==============================================================================
--- (empty file)
+++ excalibur/trunk/logger/src/java/org/apache/avalon/excalibur/logger/log4j/Log4JConfigurator.java	Mon Jun 14 07:23:58 2004
@@ -0,0 +1,124 @@
+/*
+ * Copyright 1999-2004 The Apache Software Foundation.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.avalon.excalibur.logger.log4j;
+
+import org.apache.avalon.framework.context.Context;
+import org.apache.avalon.framework.context.ContextException;
+import org.apache.log4j.helpers.LogLog;
+import org.apache.log4j.xml.DOMConfigurator;
+
+/**
+ * This is a configurator for log4j that supports variable substitution
+ * 
+ * @version CVS $Id: Log4JConfigurator.java,v 1.2 2004/06/14 14:07:09 cziegeler Exp $
+ */
+public class Log4JConfigurator extends DOMConfigurator {
+
+    protected Context context;
+    
+    public Log4JConfigurator(Context context) {
+        this.context = context;
+    }
+    
+    protected String subst(String value) {
+        try {
+          return this.substVars(value);
+        } catch (IllegalArgumentException e) {
+          LogLog.warn("Could not perform variable substitution.", e);
+
+          return value;
+        }
+    }  
+    
+    static String DELIM_START = "${";
+    static char   DELIM_STOP  = '}';
+    static int DELIM_START_LEN = 2;
+    static int DELIM_STOP_LEN  = 1;
+
+    /**
+     * This is directly copied from log4j's OptionConverter class.
+     * The only difference is the getting of a property.
+     */
+    public String substVars(String val) 
+    throws IllegalArgumentException {
+
+        StringBuffer sbuf = new StringBuffer();
+
+        int i = 0;
+        int j, k;
+
+        while(true) {
+            j=val.indexOf(DELIM_START, i);
+            if (j == -1) {
+                // no more variables
+                if(i==0) { // this is a simple string
+                    return val;
+                } else { // add the tail string which contails no variables and return the result.
+                    sbuf.append(val.substring(i, val.length()));
+                    return sbuf.toString();
+                }
+            } else {
+                sbuf.append(val.substring(i, j));
+                k = val.indexOf(DELIM_STOP, j);
+                if(k == -1) {
+                    throw new IllegalArgumentException('"'+val+
+                             "\" has no closing brace. Opening brace at position " + j
+                             + '.');
+                } else {
+                    j += DELIM_START_LEN;
+                    String key = val.substring(j, k);
+                    // first try in System properties
+                    String replacement = this.getSystemProperty(key);
+                    // then try props parameter
+                    if (replacement == null && this.context != null) {
+                        try {
+                            Object o = this.context.get(key);
+                            if ( o != null ) {
+                                replacement = o.toString();
+                            }
+                        } catch (ContextException ce) {
+                            LogLog.debug("Was not allowed to read context property \""+key+"\".");                            
+                        }
+                    }
+    
+                    if (replacement != null) {
+                        // Do variable substitution on the replacement string
+                        // such that we can solve "Hello ${x2}" as "Hello p1" 
+                        // the where the properties are
+                        // x1=p1
+                        // x2=${x1}
+                        String recursiveReplacement = substVars(replacement);
+                        sbuf.append(recursiveReplacement);
+                    }
+                    i = k + DELIM_STOP_LEN;
+                }
+            }
+        }
+    }
+    
+    /**
+     * This is directly copied from log4j's OptionConverter class.
+     * The only difference is the getting of a property.
+     */
+    public String getSystemProperty(String key) {
+        try {
+            return System.getProperty(key, null);
+        } catch(Throwable e) { // MS-Java throws com.ms.security.SecurityExceptionEx
+            LogLog.debug("Was not allowed to read system property \""+key+"\".");
+            return null;
+        }
+    }
+}

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