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The source code

/*
 * Copyright (C) The Apache Software Foundation. All rights reserved.
 *
 * This software is published under the terms of the Apache Software License
 * version 1.1, a copy of which has been included  with this distribution in
 * the LICENSE.txt file.
 */

package org.apache.log4j.helpers;

import java.util.Properties;
import java.net.URL;
import org.apache.log4j.Level;
import org.apache.log4j.spi.Configurator;
import org.apache.log4j.spi.LoggerRepository;
import org.apache.log4j.PropertyConfigurator;

// Contributors:   Avy Sharell (sharell@online.fr)
//                 Matthieu Verbert (mve@zurich.ibm.com)
//                 Colin Sampaleanu

/**
   A convenience class to convert property values to specific types.

   @author Ceki Gülcü
   @author Simon Kitching;
   @author Anders Kristensen
*/
public class OptionConverter {

  static String DELIM_START = "${";
  static char   DELIM_STOP  = '}';
  static int DELIM_START_LEN = 2;
  static int DELIM_STOP_LEN  = 1;

  /** OptionConverter is a static class. */
  private OptionConverter() {}

  public
  static
  String[] concatanateArrays(String[] l, String[] r) {
    int len = l.length + r.length;
    String[] a = new String[len];

    System.arraycopy(l, 0, a, 0, l.length);
    System.arraycopy(r, 0, a, l.length, r.length);

    return a;
  }

  public
  static
  String convertSpecialChars(String s) {
    char c;
    int len = s.length();
    StringBuffer sbuf = new StringBuffer(len);

    int i = 0;
    while(i < len) {
      c = s.charAt(i++);
      if (c == '\\') {
	c =  s.charAt(i++);
	if(c == 'n')      c = '\n';
	else if(c == 'r') c = '\r';
	else if(c == 't') c = '\t';
	else if(c == 'f') c = '\f';
	else if(c == '\b') c = '\b';
	else if(c == '\"') c = '\"';
	else if(c == '\'') c = '\'';
	else if(c == '\\') c = '\\';
      }
      sbuf.append(c);
    }
    return sbuf.toString();
  }


  /**
     Very similar to System.getProperty except
     that the {@link SecurityException} is hidden.

     @param key The key to search for.
     @param def The default value to return.
     @return the string value of the system property, or the default
     value if there is no property with that key.

     @since 1.1 */
  public
  static
  String getSystemProperty(String key, String def) {
    try {
      return System.getProperty(key, def);
    } catch(Throwable e) { // MS-Java throws com.ms.security.SecurityExceptionEx
      LogLog.debug("Was not allowed to read system property \""+key+"\".");
      return def;
    }
  }


  public
  static
  Object instantiateByKey(Properties props, String key, Class superClass,
				Object defaultValue) {

    // Get the value of the property in string form
    String className = findAndSubst(key, props);
    if(className == null) {
      LogLog.error("Could not find value for key " + key);
      return defaultValue;
    }
    // Trim className to avoid trailing spaces that cause problems.
    return OptionConverter.instantiateByClassName(className.trim(), superClass,
						  defaultValue);
  }

  /**
     If value is "true", then true is
     returned. If value is "false", then
     true is returned. Otherwise, default is
     returned.

     

Case of value is unimportant. */ public static boolean toBoolean(String value, boolean dEfault) { if(value == null) return dEfault; String trimmedVal = value.trim(); if("true".equalsIgnoreCase(trimmedVal)) return true; if("false".equalsIgnoreCase(trimmedVal)) return false; return dEfault; } public static int toInt(String value, int dEfault) { if(value != null) { String s = value.trim(); try { return Integer.valueOf(s).intValue(); } catch (NumberFormatException e) { LogLog.error("[" + s + "] is not in proper int form."); e.printStackTrace(); } } return dEfault; } /** Converts a standard or custom priority level to a Level object.

If value is of form "level#classname", then the specified class' toLevel method is called to process the specified level string; if no '#' character is present, then the default {@link org.apache.log4j.Level} class is used to process the level value.

As a special case, if the value parameter is equal to the string "NULL", then the value null will be returned.

If any error occurs while converting the value to a level, the defaultValue parameter, which may be null, is returned.

Case of value is insignificant for the level level, but is significant for the class name part, if present. @since 1.1 */ public static Level toLevel(String value, Level defaultValue) { if(value == null) return defaultValue; int hashIndex = value.indexOf('#'); if (hashIndex == -1) { if("NULL".equalsIgnoreCase(value)) { return null; } else { // no class name specified : use standard Level class return(Level) Level.toLevel(value, defaultValue); } } Level result = defaultValue; String clazz = value.substring(hashIndex+1); String levelName = value.substring(0, hashIndex); // This is degenerate case but you never know. if("NULL".equalsIgnoreCase(levelName)) { return null; } LogLog.debug("toLevel" + ":class=[" + clazz + "]" + ":pri=[" + levelName + "]"); try { Class customLevel = Loader.loadClass(clazz); // get a ref to the specified class' static method // toLevel(String, org.apache.log4j.Level) Class[] paramTypes = new Class[] { String.class, org.apache.log4j.Level.class }; java.lang.reflect.Method toLevelMethod = customLevel.getMethod("toLevel", paramTypes); // now call the toLevel method, passing level string + default Object[] params = new Object[] {levelName, defaultValue}; Object o = toLevelMethod.invoke(null, params); result = (Level) o; } catch(ClassNotFoundException e) { LogLog.warn("custom level class [" + clazz + "] not found."); } catch(NoSuchMethodException e) { LogLog.warn("custom level class [" + clazz + "]" + " does not have a constructor which takes one string parameter", e); } catch(java.lang.reflect.InvocationTargetException e) { LogLog.warn("custom level class [" + clazz + "]" + " could not be instantiated", e); } catch(ClassCastException e) { LogLog.warn("class [" + clazz + "] is not a subclass of org.apache.log4j.Level", e); } catch(IllegalAccessException e) { LogLog.warn("class ["+clazz+ "] cannot be instantiated due to access restrictions", e); } catch(Exception e) { LogLog.warn("class ["+clazz+"], level ["+levelName+ "] conversion failed.", e); } return result; } public static long toFileSize(String value, long dEfault) { if(value == null) return dEfault; String s = value.trim().toUpperCase(); long multiplier = 1; int index; if((index = s.indexOf("KB")) != -1) { multiplier = 1024; s = s.substring(0, index); } else if((index = s.indexOf("MB")) != -1) { multiplier = 1024*1024; s = s.substring(0, index); } else if((index = s.indexOf("GB")) != -1) { multiplier = 1024*1024*1024; s = s.substring(0, index); } if(s != null) { try { return Long.valueOf(s).longValue() * multiplier; } catch (NumberFormatException e) { LogLog.error("[" + s + "] is not in proper int form."); LogLog.error("[" + value + "] not in expected format.", e); } } return dEfault; } /** Find the value corresponding to key in props. Then perform variable substitution on the found value. */ public static String findAndSubst(String key, Properties props) { String value = props.getProperty(key); if(value == null) return null; try { return substVars(value, props); } catch(IllegalArgumentException e) { LogLog.error("Bad option value ["+value+"].", e); return value; } } /** Instantiate an object given a class name. Check that the className is a subclass of superClass. If that test fails or the object could not be instantiated, then defaultValue is returned. @param className The fully qualified class name of the object to instantiate. @param superClass The class to which the new object should belong. @param defaultValue The object to return in case of non-fulfillment */ public static Object instantiateByClassName(String className, Class superClass, Object defaultValue) { if(className != null) { try { Class classObj = Loader.loadClass(className); if(!superClass.isAssignableFrom(classObj)) { LogLog.error("A \""+className+"\" object is not assignable to a \""+ superClass.getName() + "\" variable."); LogLog.error("The class \""+ superClass.getName()+"\" was loaded by "); LogLog.error("["+superClass.getClassLoader()+"] whereas object of type "); LogLog.error("\"" +classObj.getName()+"\" was loaded by [" +classObj.getClassLoader()+"]."); return defaultValue; } return classObj.newInstance(); } catch (Exception e) { LogLog.error("Could not instantiate class [" + className + "].", e); } } return defaultValue; } /** Perform variable substitution in string val from the values of keys found in the system propeties.

The variable substitution delimeters are ${ and }.

For example, if the System properties contains "key=value", then the call

     String s = OptionConverter.substituteVars("Value of key is ${key}.");
     
will set the variable s to "Value of key is value.".

If no value could be found for the specified key, then the props parameter is searched, if the value could not be found there, then substitution defaults to the empty string.

For example, if system propeties contains no value for the key "inexistentKey", then the call

     String s = OptionConverter.subsVars("Value of inexistentKey is [${inexistentKey}]");
     
will set s to "Value of inexistentKey is []"

An {@link java.lang.IllegalArgumentException} is thrown if val contains a start delimeter "${" which is not balanced by a stop delimeter "}".

Author Avy Sharell

@param val The string on which variable substitution is performed. @throws IllegalArgumentException if val is malformed. */ public static String substVars(String val, Properties props) 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 = getSystemProperty(key, null); // then try props parameter if(replacement == null && props != null) { replacement = props.getProperty(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, props); sbuf.append(recursiveReplacement); } i = k + DELIM_STOP_LEN; } } } } /** Configure log4j given a URL.

The url must point to a file or resource which will be interpreted by a new instance of a log4j configurator.

All configurations steps are taken on the hierarchy passed as a parameter.

@param url The location of the configuration file or resource. @param clazz The classname, of the log4j configurator which will parse the file or resource at url. This must be a subclass of {@link Configurator}, or null. If this value is null then a default configurator of {@link PropertyConfigurator} is used, unless the filename pointed to by url ends in '.xml', in which case {@link org.apache.log4j.xml.DOMConfigurator} is used. @param hierarchy The {@link org.apache.log4j.Hierarchy} to act on. @since 1.1.4 */ static public void selectAndConfigure(URL url, String clazz, LoggerRepository hierarchy) { Configurator configurator = null; String filename = url.getFile(); if(clazz == null && filename != null && filename.endsWith(".xml")) { clazz = "org.apache.log4j.xml.DOMConfigurator"; } if(clazz != null) { LogLog.debug("Preferred configurator class: " + clazz); configurator = (Configurator) instantiateByClassName(clazz, Configurator.class, null); if(configurator == null) { LogLog.error("Could not instantiate configurator ["+clazz+"]."); return; } } else { configurator = new PropertyConfigurator(); } configurator.doConfigure(url, hierarchy); } }

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