Class ModifiedSelector

All Implemented Interfaces:
ExtendFileSelector, FileSelector, Parameterizable

public class ModifiedSelector
extends BaseExtendSelector

Selector class that uses Algorithm, Cache and Comparator for its work. The Algorithm is used for computing a hashvalue for a file. The Comparator decides whether to select or not. The Cache stores the other value for comparison by the Comparator in a persistent manner.

The ModifiedSelector is implemented as a CoreSelector and uses default values for all its attributes therefore the simpliest example is


The same example rewritten as CoreSelector with setting the all values (same as defaults are) would be


And the same rewritten as CustomSelector would be


All these three examples copy the files from src to dest using the ModifiedSelector. The ModifiedSelector uses the PropertyfileCache , the DigestAlgorithm and the EqualComparator for its work. The PropertyfileCache stores key-value-pairs in a simple java properties file. The filename is The update flag lets the selector update the values in the cache (and on first call creates the cache). The DigestAlgorithm computes a hashvalue using the class with its MD5-Algorithm and its standard provider. The new computed hashvalue and the stored one are compared by the EqualComparator which returns 'true' (more correct a value not equals zero (1)) if the values are not the same using simple String comparison.

A useful scenario for this selector is inside a build environment for homepage generation (e.g. with Apache Forrest).

      generate the site using forrest 

      upload the changed files 
Here all changed files are uploaded to the server. The ModifiedSelector saves therefore much upload time.

This selector supports the following nested param's:
cache propertyfile which cache implementation should be used
  • propertyfile - using java.util.Properties
no, defaults to 'propertyfile'
algorithm hashvalue | digest which algorithm implementation should be used
  • hashvalue - loads the file content into a String and uses its hashValue() method
  • digest - uses class
  • no, defaults to digest
    comparator equal | role which comparator implementation should be used
  • equal - simple comparison using String.equals()
  • role - uses java.text.RuleBasedCollator class
  • no, defaults to equal
    update true | false If set to true, the cache will be stored, otherwise the values will be lost. no, defaults to true
    seldirs true | false If set to true, directories will be selected otherwise not no, defaults to true
    cache.* depends on used cache value is stored and given to the Cache-Object for initialisation depends on used cache
    algorithm.* depends on used algorithm value is stored and given to the Algorithm-Object for initialisation depends on used algorithm
    comparator.* depends on used comparator value is stored and given to the Comparator-Object for initialisation depends on used comparator
    If another name is used a BuildException "Invalid parameter" is thrown.

    This selector uses reflection for setting the values of its three interfaces (using therefore no special 'configuration interfaces' has to be implemented by new caches, algorithms or comparators. All present setXX methods can be used. E.g. the DigestAlgorithm can use a specified provider for computing its value. For selecting this there is a setProvider(String providername) method. So you can use a nested .

    Ant 1.6

    Nested Class Summary
    static class ModifiedSelector.AlgorithmName
    static class ModifiedSelector.CacheName
    static class ModifiedSelector.ComparatorName
    Field Summary
    Fields inherited from class
    Fields inherited from class
    checked, description, ref
    Fields inherited from class
    Constructor Summary
    Method Summary
     void addParam(Parameter parameter)
              Support for nested <param> tags.
     void addParam(java.lang.String key, java.lang.Object value)
              Support for nested <param> tags.
     void configure()
              Configures this Selector.
     Algorithm getAlgorithm()
     Cache getCache()
     java.util.Comparator getComparator()
     boolean isSelected( basedir, java.lang.String filename, file)
              Implementation of BaseExtendSelector.isSelected().
     void setAlgorithm(ModifiedSelector.AlgorithmName name)
     void setCache(ModifiedSelector.CacheName name)
     void setComparator(ModifiedSelector.ComparatorName name)
     void setParameters(Parameter[] parameters)
              Defined in
     void setSeldirs(boolean seldirs)
              Support for seldirs attribute.
     void setUpdate(boolean update)
              Support for update attribute.
     java.lang.String toString()
              Override Object.toString().
    protected  void tryToSetAParameter(java.lang.Object obj, java.lang.String name, java.lang.String value)
              Try to set a value on an object using reflection.
     void useParameter(Parameter parameter)
              Support for nested tags.
     void verifySettings()
              Overrides BaseSelector.verifySettings().
    Methods inherited from class
    Methods inherited from class
    getError, setError, validate
    Methods inherited from class
    checkAttributesAllowed, checkChildrenAllowed, circularReference, dieOnCircularReference, getCheckedRef, getDescription, getRefid, isChecked, isReference, noChildrenAllowed, setChecked, setDescription, setRefid, tooManyAttributes
    Methods inherited from class
    getProject, log, log, setProject
    Methods inherited from class java.lang.Object
    clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

    Constructor Detail


    public ModifiedSelector()

    Method Detail


    public void verifySettings()
    Overrides BaseSelector.verifySettings().

    verifySettings in class BaseSelector


    public void configure()
    Configures this Selector. Does this work only once per Selector object.

    Because some problems while configuring from Selector the configuration is done in the following order:

    1. collect the configuration data
    2. wait for the first isSelected() call
    3. set the default values
    4. set values for name pattern '*': update, cache, algorithm, comparator
    5. set values for name pattern '*.*: cache.cachefile, ...

    This configuration algorithm is needed because you don't know the order of arriving config-data. E.g. if you first set the cache.cachefilename and after that the cache itself, the default value for cachefilename is used, because setting the cache implies creating a new Cache instance - with its defaults.


    public boolean isSelected( basedir,
                              java.lang.String filename,
    Implementation of BaseExtendSelector.isSelected().

    Specified by:
    isSelected in interface FileSelector
    Specified by:
    isSelected in class BaseExtendSelector
    basedir - as described in BaseExtendSelector
    filename - as described in BaseExtendSelector
    file - as described in BaseExtendSelector
    as described in BaseExtendSelector


    public void setUpdate(boolean update)
    Support for update attribute.

    update - new value


    public void setSeldirs(boolean seldirs)
    Support for seldirs attribute.

    seldirs - new value


    public void addParam(java.lang.String key,
                         java.lang.Object value)
    Support for nested <param> tags.

    key - the key of the parameter
    value - the value of the parameter


    public void addParam(Parameter parameter)
    Support for nested <param> tags.

    parameter - the parameter object


    public void setParameters(Parameter[] parameters)
    Defined in Overwrite implementation in superclass because only special parameters are valid.

    Specified by:
    setParameters in interface Parameterizable
    setParameters in class BaseExtendSelector
    parameters - the complete set of parameters for this selector
    See Also:


    public void useParameter(Parameter parameter)
    Support for nested tags. Parameter named cache, algorithm, comparator or update are mapped to the respective set-Method. Parameter which names starts with cache. or algorithm. or comparator. are tried to set on the appropriate object via its set-methods. Other parameters are invalid and an BuildException will be thrown.

    parameter - Key and value as parameter object


    protected void tryToSetAParameter(java.lang.Object obj,
                                      java.lang.String name,
                                      java.lang.String value)
    Try to set a value on an object using reflection. Helper method for easier access to IntrospectionHelper.setAttribute().

    obj - the object on which the attribute should be set
    name - the attributename
    value - the new value


    public java.lang.String toString()
    Override Object.toString().

    toString in class java.lang.Object
    information about this selector


    public Cache getCache()


    public void setCache(ModifiedSelector.CacheName name)


    public Algorithm getAlgorithm()


    public void setAlgorithm(ModifiedSelector.AlgorithmName name)


    public java.util.Comparator getComparator()


    public void setComparator(ModifiedSelector.ComparatorName name)

    Copyright 2000-2005 Apache Software Foundation. All Rights Reserved.