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

Class ModifiedSelector

Implemented Interfaces:
BuildListener, Cloneable, EventListener, ExtendFileSelector, FileSelector, Parameterizable, ResourceSelector

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 class
ModifiedSelector.AlgorithmName
The enumerated type for algorithm.
static class
ModifiedSelector.CacheName
The enumerated type for cache.
static class
ModifiedSelector.ComparatorName
The enumerated type for algorithm.

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, ref

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

description, location, project

Constructor Summary

ModifiedSelector()
Bean-Constructor.

Method Summary

void
addClasspath(Path path)
Add the classpath.
void
addParam(String key, Object value)
Support for nested <param> tags.
void
addParam(Parameter parameter)
Support for nested <param> tags.
void
buildFinished(BuildEvent event)
Signals that the last target has finished.
void
buildStarted(BuildEvent event)
Signals that a build has started.
void
configure()
Configures this Selector.
Algorithm
getAlgorithm()
Get the algorithm type to use.
Cache
getCache()
Get the cache type to use.
ClassLoader
getClassLoader()
Returns and initializes the classloader for this class.
Comparator
getComparator()
Get the comparator type to use.
boolean
getDelayUpdate()
Getter for the delay update
int
getModified()
Getter for the modified count
boolean
isSelected(File basedir, String filename, File file)
Implementation of BaseExtendSelector.isSelected().
boolean
isSelected(Resource resource)
Implementation of ResourceSelector.isSelected().
protected Object
loadClass(String classname, String msg, Class type)
Loads the specified class and initializes an object of that class.
void
messageLogged(BuildEvent event)
Signals a message logging event.
protected void
saveCache()
save the cache file
void
setAlgorithm(ModifiedSelector.AlgorithmName name)
Set the algorithm type to use.
void
setAlgorithmClass(String classname)
Setter for algorithmClass.
void
setCache(ModifiedSelector.CacheName name)
Set the cache type to use.
void
setCacheClass(String classname)
Setter for cacheClass.
void
setClassLoader(ClassLoader loader)
Set the used ClassLoader.
void
setComparator(ModifiedSelector.ComparatorName name)
Set the comparator type to use.
void
setComparatorClass(String classname)
Setter for comparatorClass.
void
setDelayUpdate(boolean delayUpdate)
Setter for the delay update
void
setModified(int modified)
Setter for the modified count
void
setParameters(Parameter[] parameters)
Defined in org.apache.tools.ant.types.Parameterizable.
void
setSeldirs(boolean seldirs)
Support for seldirs attribute.
void
setSelres(boolean newValue)
Support for selres attribute.
void
setUpdate(boolean update)
Support for update attribute.
void
targetFinished(BuildEvent event)
Signals that a target has finished.
void
targetStarted(BuildEvent event)
Signals that a target is starting.
void
taskFinished(BuildEvent event)
Signals that a task has finished.
void
taskStarted(BuildEvent event)
Signals that a task is starting.
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, clone, dieOnCircularReference, dieOnCircularReference, dieOnCircularReference, getCheckedRef, getCheckedRef, getCheckedRef, getCheckedRef, getDataTypeName, getRefid, invokeCircularReferenceCheck, isChecked, isReference, noChildrenAllowed, setChecked, setRefid, toString, tooManyAttributes

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

clone, getDescription, getLocation, getProject, log, log, setDescription, setLocation, setProject

Constructor Details

ModifiedSelector

public ModifiedSelector()
Bean-Constructor.

Method Details

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.
Specified by:
buildFinished in interface BuildListener
Parameters:
event - recieved BuildEvent

buildStarted

public void buildStarted(BuildEvent event)
Signals that a build has started.
Specified by:
buildStarted in interface BuildListener
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(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

isSelected

public boolean isSelected(Resource resource)
Implementation of ResourceSelector.isSelected().
Specified by:
isSelected in interface ResourceSelector
Parameters:
resource - The resource to check
Returns:
whether the resource is selected

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.
Specified by:
messageLogged in interface BuildListener
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.
Specified by:
setParameters in interface Parameterizable
Overrides:
setParameters in interface BaseExtendSelector
Parameters:
parameters - the parameters to set.
See Also:
addParam(String,Object).

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.
Specified by:
targetFinished in interface BuildListener
Parameters:
event - recieved BuildEvent

targetStarted

public void targetStarted(BuildEvent event)
Signals that a target is starting.
Specified by:
targetStarted in interface BuildListener
Parameters:
event - received BuildEvent

taskFinished

public void taskFinished(BuildEvent event)
Signals that a task has finished.
Specified by:
taskFinished in interface BuildListener
Parameters:
event - recieved BuildEvent

taskStarted

public void taskStarted(BuildEvent event)
Signals that a task is starting.
Specified by:
taskStarted in interface BuildListener
Parameters:
event - recieved BuildEvent

toString

public String toString()
Override Object.toString().
Overrides:
toString in interface DataType
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