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

Class ModifiedSelector

public class ModifiedSelector extends BaseExtendSelector implements BuildListener, ResourceSelector

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

   <copy todir="dest">
       <filelist dir="src">
           <modified/>
       </filelist>
   </copy>
 

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

   <copy todir="dest">
       <filelist dir="src">
           <modified update="true"
                     cache="propertyfile"
                     algorithm="digest"
                     comparator="equal">
               <param name="cache.cachefile"     value="cache.properties"/>
               <param name="algorithm.algorithm" value="MD5"/>
           </modified>
       </filelist>
   </copy>
 

And the same rewritten as CustomSelector would be

   <copy todir="dest">
       <filelist dir="src">
           <custom class="org.apache.tools.ant.type.selectors.ModifiedSelector">
               <param name="update"     value="true"/>
               <param name="cache"      value="propertyfile"/>
               <param name="algorithm"  value="digest"/>
               <param name="comparator" value="equal"/>
               <param name="cache.cachefile"     value="cache.properties"/>
               <param name="algorithm.algorithm" value="MD5"/>
           </custom>
       </filelist>
   </copy>
 

If you want to provide your own interface implementation you can do that via the *classname attributes. If the classes are not on Ant's core classpath, you will have to provide the path via nested <classpath> element, so that the selector can find the classes.

   <modified cacheclassname="com.mycompany.MyCache">
       <classpath>
           <pathelement location="lib/mycompony-antutil.jar"/>
       </classpath>
   </modified>
 

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).

 <target name="generate-and-upload-site">
     <echo> generate the site using forrest </echo>
     <antcall target="site"/>

     <echo> upload the changed files </echo>
     <ftp server="${ftp.server}" userid="${ftp.user}" password="${ftp.pwd}">
         <fileset dir="htdocs/manual">
             <modified/>
         </fileset>
     </ftp>
 </target>
 
Here all changed files are uploaded to the server. The ModifiedSelector saves therefore much upload time.

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 <param name="algorithm.provider" value="MyProvider"/>.

Since: Ant 1.6

Nested Class Summary
static classModifiedSelector.AlgorithmName
The enumerated type for algorithm.
static classModifiedSelector.CacheName
The enumerated type for cache.
static classModifiedSelector.ComparatorName
The enumerated type for algorithm.
Constructor Summary
ModifiedSelector()
Bean-Constructor.
Method Summary
voidaddClasspath(Path path)
Add the classpath.
voidaddParam(String key, Object value)
Support for nested <param> tags.
voidaddParam(Parameter parameter)
Support for nested <param> tags.
voidbuildFinished(BuildEvent event)
Signals that the last target has finished.
voidbuildStarted(BuildEvent event)
Signals that a build has started.
voidconfigure()
Configures this Selector.
AlgorithmgetAlgorithm()
Get the algorithm type to use.
CachegetCache()
Get the cache type to use.
ClassLoadergetClassLoader()
Returns and initializes the classloader for this class.
ComparatorgetComparator()
Get the comparator type to use.
booleangetDelayUpdate()
Getter for the delay update
intgetModified()
Getter for the modified count
booleanisSelected(Resource resource)
Implementation of ResourceSelector.isSelected().
booleanisSelected(File basedir, String filename, File file)
Implementation of BaseExtendSelector.isSelected().
protected ObjectloadClass(String classname, String msg, Class type)
Loads the specified class and initializes an object of that class.
voidmessageLogged(BuildEvent event)
Signals a message logging event.
protected voidsaveCache()
save the cache file
voidsetAlgorithm(ModifiedSelector.AlgorithmName name)
Set the algorithm type to use.
voidsetAlgorithmClass(String classname)
Setter for algorithmClass.
voidsetCache(ModifiedSelector.CacheName name)
Set the cache type to use.
voidsetCacheClass(String classname)
Setter for cacheClass.
voidsetClassLoader(ClassLoader loader)
Set the used ClassLoader.
voidsetComparator(ModifiedSelector.ComparatorName name)
Set the comparator type to use.
voidsetComparatorClass(String classname)
Setter for comparatorClass.
voidsetDelayUpdate(boolean delayUpdate)
Setter for the delay update
voidsetModified(int modified)
Setter for the modified count
voidsetParameters(Parameter[] parameters)
Defined in org.apache.tools.ant.types.Parameterizable.
voidsetSeldirs(boolean seldirs)
Support for seldirs attribute.
voidsetSelres(boolean newValue)
Support for selres attribute.
voidsetUpdate(boolean update)
Support for update attribute.
voidtargetFinished(BuildEvent event)
Signals that a target has finished.
voidtargetStarted(BuildEvent event)
Signals that a target is starting.
voidtaskFinished(BuildEvent event)
Signals that a task has finished.
voidtaskStarted(BuildEvent event)
Signals that a task is starting.
StringtoString()
Override Object.toString().
protected voidtryToSetAParameter(Object obj, String name, String value)
Try to set a value on an object using reflection.
voiduseParameter(Parameter parameter)
Support for nested tags.
voidverifySettings()
Overrides BaseSelector.verifySettings().

Constructor Detail

ModifiedSelector

public ModifiedSelector()
Bean-Constructor.

Method Detail

addClasspath

public void addClasspath(Path path)
Add the classpath.

Parameters: path the classpath

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

buildFinished

public void buildFinished(BuildEvent event)
Signals that the last target has finished.

Parameters: event recieved BuildEvent

buildStarted

public void buildStarted(BuildEvent event)
Signals that a build has started.

Parameters: event recieved BuildEvent

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()
Get the algorithm type to use.

Returns: the enumerated algorithm type

getCache

public Cache getCache()
Get the cache type to use.

Returns: the enumerated cache type

getClassLoader

public ClassLoader getClassLoader()
Returns and initializes the classloader for this class.

Returns: the classloader

getComparator

public Comparator getComparator()
Get the comparator type to use.

Returns: the enumerated comparator type

getDelayUpdate

public boolean getDelayUpdate()
Getter for the delay update

Returns: true if we should delay for performance

getModified

public int getModified()
Getter for the modified count

Returns: modified count

isSelected

public boolean isSelected(Resource resource)
Implementation of ResourceSelector.isSelected().

Parameters: resource The resource to check

Returns: whether the resource is selected

See Also: isSelected

isSelected

public boolean isSelected(File basedir, String filename, File file)
Implementation of BaseExtendSelector.isSelected().

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

Returns: as described in BaseExtendSelector

loadClass

protected Object loadClass(String classname, String msg, Class type)
Loads the specified class and initializes an object of that class. Throws a BuildException using the given message if an error occurs during loading/instantiation or if the object is not from the given type.

Parameters: classname the classname msg the message-part for the BuildException type the type to check against

Returns: a castable object

messageLogged

public void messageLogged(BuildEvent event)
Signals a message logging event.

Parameters: event recieved BuildEvent

saveCache

protected void saveCache()
save the cache file

setAlgorithm

public void setAlgorithm(ModifiedSelector.AlgorithmName name)
Set the algorithm type to use.

Parameters: name an enumerated algorithm type.

setAlgorithmClass

public void setAlgorithmClass(String classname)
Setter for algorithmClass.

Parameters: classname new value

setCache

public void setCache(ModifiedSelector.CacheName name)
Set the cache type to use.

Parameters: name an enumerated cache type.

setCacheClass

public void setCacheClass(String classname)
Setter for cacheClass.

Parameters: classname new value

setClassLoader

public void setClassLoader(ClassLoader loader)
Set the used ClassLoader. If you invoke this selector by API (e.g. inside some testcases) the selector will use a different classloader for loading the interface implementations than the caller. Therefore you will get a ClassCastException if you get the implementations from the selector and cast them.

Parameters: loader the ClassLoader to use

setComparator

public void setComparator(ModifiedSelector.ComparatorName name)
Set the comparator type to use.

Parameters: name an enumerated comparator type.

setComparatorClass

public void setComparatorClass(String classname)
Setter for comparatorClass.

Parameters: classname new value

setDelayUpdate

public void setDelayUpdate(boolean delayUpdate)
Setter for the delay update

Parameters: delayUpdate true if we should delay for performance

setModified

public void setModified(int modified)
Setter for the modified count

Parameters: modified count

setParameters

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

Parameters: parameters the parameters to set.

See Also: .

setSeldirs

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

Parameters: seldirs new value

setSelres

public void setSelres(boolean newValue)
Support for selres attribute.

Parameters: newValue the new value

setUpdate

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

Parameters: update new value

targetFinished

public void targetFinished(BuildEvent event)
Signals that a target has finished.

Parameters: event recieved BuildEvent

targetStarted

public void targetStarted(BuildEvent event)
Signals that a target is starting.

Parameters: event received BuildEvent

taskFinished

public void taskFinished(BuildEvent event)
Signals that a task has finished.

Parameters: event recieved BuildEvent

taskStarted

public void taskStarted(BuildEvent event)
Signals that a task is starting.

Parameters: event recieved BuildEvent

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().