Ant - Listeners & Loggers

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Ant allows the build process to be monitored using listeners and loggers.

Listeners

Ant provides following events to be captured using listeners.

• build started

• build finished

• target started

• target finished

• task started

• task finished

• message logged

Custom listeners can be registered on command line using -listener argument.

Loggers

Loggers extends listeners capabilities and add the following features

• Can log information to console or file using -logfile argument

• Can log using logging levels like -quiet, -verbose, -debug

• Are emacs-mode aware

Built-in Listeners/loggers

• org.apache.tools.ant.DefaultLogger − The logger used implicitly unless overridden with the -logger command-line switch.

• org.apache.tools.ant.NoBannerLogger − This logger omits output of empty target output.

• org.apache.tools.ant.listener.MailLogger − Extends DefaultLogger such that output is still generated the same, and when the build is finished an e-mail can be sent.

• org.apache.tools.ant.listener.AnsiColorLogger − Colorifies the build output.

• org.apache.tools.ant.listener.Log4jListener − Passes events to Apache Log4j for highly customizable logging.

• org.apache.tools.ant.XmlLogger − Writes the build information to an XML file.

• org.apache.tools.ant.TimestampedLogger − Prints the time that a build finished

• org.apache.tools.ant.listener.BigProjectLogger − Prints the project name every target

• org.apache.tools.ant.listener.SimpleBigProjectLogger − Prints the project name for subprojects only, otherwise like NoBannerLogger Since Ant 1.8.1

• org.apache.tools.ant.listener.ProfileLogger − The default logger, with start times, end times and durations added for each task and target.

Example

Create build.xml with the following content:

<?xml version="1.0"?>
<project name="sample" basedir="." default="copy">
   <target name="copy">
     <echo>File Copied</echo>
   </target>
</project>

Output

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

F:\tutorialspoint\ant>ant -logger org.apache.tools.ant.listener.TimestampedLogger
Buildfile: F:\tutorialspoint\ant\build.xml

copy:
   [echo] File Copied

BUILD SUCCESSFUL - at 03/12/21, 11:24 AM
Total time: 0 seconds

F:\tutorialspoint\ant>ant -logger org.apache.tools.ant.XmlLogger -verbose -logfile build_log.xml
Apache Ant(TM) version 1.10.12 compiled on October 13 2021
Trying the default build file: build.xml
Buildfile: F:\tutorialspoint\ant\build.xml

Now you can check build_log.xml file is created with relevant logs.