org.apache.tools.ant.types.selectors.modifiedselector

Class ModifiedSelector

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 cache.properties. 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 java.security.MessageDigest 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:

namevaluesdescriptionrequired
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 java.security.MessageDigest 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 org.apache.tools.ant.IntrospectionHelper) 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 .

    Version:
    2003-09-13

    Since:
    Ant 1.6

    Nested Class Summary

    static class
    ModifiedSelector.AlgorithmName
    static class
    ModifiedSelector.CacheName
    static class
    ModifiedSelector.ComparatorName

    Field Summary

    Fields inherited from class org.apache.tools.ant.types.selectors.BaseExtendSelector

    parameters

    Fields inherited from class org.apache.tools.ant.types.DataType

    checked, description, ref

    Fields inherited from class org.apache.tools.ant.ProjectComponent

    project

    Constructor Summary

    ModifiedSelector()
    Bean-Constructor.

    Method Summary

    void
    addParam(String key, Object value)
    Support for nested <param> tags.
    void
    addParam(Parameter parameter)
    Support for nested <param> tags.
    void
    configure()
    Configures this Selector.
    Algorithm
    getAlgorithm()
    Cache
    getCache()
    Comparator
    getComparator()
    boolean
    isSelected(File basedir, String filename, File 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 org.apache.tools.ant.types.Parameterizable.
    void
    setSeldirs(boolean seldirs)
    Support for seldirs attribute.
    void
    setUpdate(boolean update)
    Support for update attribute.
    String
    toString()
    Override Object.toString().
    protected void
    tryToSetAParameter(Object obj, String name, 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 org.apache.tools.ant.types.selectors.BaseExtendSelector

    getParameters, isSelected, setParameters

    Methods inherited from class org.apache.tools.ant.types.selectors.BaseSelector

    getError, isSelected, setError, validate, verifySettings

    Methods inherited from class org.apache.tools.ant.types.DataType

    checkAttributesAllowed, checkChildrenAllowed, circularReference, dieOnCircularReference, getCheckedRef, getDescription, getRefid, isChecked, isReference, noChildrenAllowed, setChecked, setDescription, setRefid, tooManyAttributes

    Methods inherited from class org.apache.tools.ant.ProjectComponent

    getProject, log, log, setProject

    Constructor Details

    ModifiedSelector

    public ModifiedSelector()
    Bean-Constructor.

    Method Details

    addParam

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

    Parameters:
    key - the key of the parameter
    value - the value of the parameter


    addParam

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

    Parameters:
    parameter - the parameter object


    configure

    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.


    getAlgorithm

    public Algorithm getAlgorithm()


    getCache

    public Cache getCache()


    getComparator

    public Comparator getComparator()


    isSelected

    public boolean isSelected(File basedir,
                              String filename,
                              File file)
    Implementation of BaseExtendSelector.isSelected().
    Specified by:
    isSelected in interface FileSelector
    Overrides:
    isSelected in interface BaseExtendSelector

    Parameters:
    basedir - as described in BaseExtendSelector
    filename - as described in BaseExtendSelector
    file - as described in BaseExtendSelector

    Returns:
    as described in BaseExtendSelector


    setAlgorithm

    public void setAlgorithm(ModifiedSelector.AlgorithmName name)


    setCache

    public void setCache(ModifiedSelector.CacheName name)


    setComparator

    public void setComparator(ModifiedSelector.ComparatorName name)


    setParameters

    public void setParameters(Parameter[] parameters)
    Defined in org.apache.tools.ant.types.Parameterizable. Overwrite implementation in superclass because only special parameters are valid.
    Specified by:
    setParameters in interface Parameterizable
    Overrides:
    setParameters in interface BaseExtendSelector

    See Also:
    addParam(String,Object).


    setSeldirs

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

    Parameters:
    seldirs - new value


    setUpdate

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

    Parameters:
    update - new value


    toString

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

    Returns:
    information about this selector


    tryToSetAParameter

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

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


    useParameter

    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.

    Parameters:
    parameter - Key and value as parameter object


    verifySettings

    public void verifySettings()
    Overrides BaseSelector.verifySettings().
    Overrides:
    verifySettings in interface BaseSelector


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