org.apache.log4j.helpers
Class OptionConverter

java.lang.Object
  org.apache.log4j.helpers.OptionConverter

public class OptionConverter
extends Object

A convenience class to convert property values to specific types.

Author:

Ceki Gülcü, Simon Kitching;, Anders Kristensen

Method Summary

static String[]	concatanateArrays(String[] l, String[] r)
static String	convertSpecialChars(String s)
static String	findAndSubst(String key, Properties props) Find the value corresponding to key in props.
static String	getSystemProperty(String key, String def) Very similar to System.getProperty except that the SecurityException is hidden.
static Object	instantiateByClassName(String className, Class superClass, Object defaultValue) Instantiate an object given a class name.
static Object	instantiateByKey(Properties props, String key, Class superClass, Object defaultValue)
static void	selectAndConfigure(URL url, String clazz, LoggerRepository hierarchy) Configure log4j given a URL.
static String	substVars(String val, Properties props) Perform variable substitution in string val from the values of keys found in the system propeties.
static boolean	toBoolean(String value, boolean dEfault) If value is "true", then true is returned.
static long	toFileSize(String value, long dEfault)
static int	toInt(String value, int dEfault)
static Level	toLevel(String value, Level defaultValue) Converts a standard or custom priority level to a Level object.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

concatanateArrays

public static String[] concatanateArrays(String[] l,
                                         String[] r)

convertSpecialChars

public static String convertSpecialChars(String s)

getSystemProperty

public static String getSystemProperty(String key,
                                       String def)

Very similar to System.getProperty except that the SecurityException is hidden.

Parameters:

key - The key to search for.

def - The default value to return.

Returns:

the string value of the system property, or the default value if there is no property with that key.

Since:

1.1

instantiateByKey

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

toBoolean

public static boolean toBoolean(String value,
                                boolean dEfault)

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.

toInt

public static int toInt(String value,
                        int dEfault)

toLevel

public static Level toLevel(String value,
                            Level defaultValue)

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 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

toFileSize

public static long toFileSize(String value,
                              long dEfault)

findAndSubst

public static String findAndSubst(String key,
                                  Properties props)

Find the value corresponding to key in props. Then perform variable substitution on the found value.

instantiateByClassName

public static Object instantiateByClassName(String className,
                                            Class superClass,
                                            Object defaultValue)

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.

Parameters:

className - The fully qualified class name of the object to instantiate.

superClass - The class to which the new object should belong.

defaultValue - The object to return in case of non-fulfillment

substVars

public static String substVars(String val,
                               Properties props)
                        throws IllegalArgumentException

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 IllegalArgumentException is thrown if val contains a start delimeter "${" which is not balanced by a stop delimeter "}".

Author Avy Sharell

Parameters:

val - The string on which variable substitution is performed.

Throws:

IllegalArgumentException - if val is malformed.

selectAndConfigure

public static void selectAndConfigure(URL url,
                                      String clazz,
                                      LoggerRepository hierarchy)

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.

Parameters:

url - The location of the configuration file or resource.

clazz - The classname, of the log4j configurator which will parse the file or resource at url. This must be a subclass of Configurator, or null. If this value is null then a default configurator of PropertyConfigurator is used, unless the filename pointed to by url ends in '.xml', in which case DOMConfigurator is used.

hierarchy - The Hierarchy to act on.

Since:

1.1.4