Ant allows to create and use custom components very easily. Custom Components can be created by implementing Condition, Selector, Filter etc. interfaces. Once a class is ready, we can use typedef to create the component within build.xml to be used under any target.

Syntax

First define a class as Ant custom component say TextSelector.java then in build.xml, define a selector.

<typedef name="text-selector" classname="TextSelector" classpath="."/>

Then use that component within a target.

<target name="copy">
   <copy todir="${dest.dir}" filtering="true">
      <fileset dir="${src.dir}">
         <text-selector/>  
      </fileset>
   </copy>
</target>

Example

Create TextSelector.java with the following content and put the same in same place as build.xml −

import java.io.File;  
import org.apache.tools.ant.types.selectors.FileSelector;  
public class TextFilter implements FileSelector {  
   public boolean isSelected(File b, String filename, File f) {  
      return filename.toLowerCase().endsWith(".txt");  
   }  
}

Create a text1.txt and a text2.java in src directory. Target is to be copy only .txt file to build directory.

Create build.xml with the following content −

<?xml version="1.0"?>
<project name="sample" basedir="." default="copy">
   <property name="src.dir" value="src"/>
   <property name="dest.dir" value="build"/>
   <typedef name="text-selector" classname="TextSelector"  classpath="."/>
   <target name="copy">
      <copy todir="${dest.dir}" filtering="true">
         <fileset dir="${src.dir}">
            <text-selector/>  
         </fileset>
      </copy>
   </target>
</project>

Output

Running Ant on the above build file produces the following output −

F:tutorialspointant>ant
Buildfile: F:tutorialspointantbuild.xml

copy:
   [copy] Copying 1 file to F:tutorialspointantbuild

BUILD SUCCESSFUL
Total time: 0 seconds

Now only .txt file is copied.