Gradle Logging Output Levels

Question

In my project classes I've used java.util.logging.Logger and added various log output's throughout my code, using various log levels ie.

src/main/java/Run.java

import java.util.logging.Level;
import java.util.logging.Logger;

public class Run{


    public static void main( String args[] ){
      System.out.println("Hello World");

      logger.log(Level.CONFIG, "Just some config info");
      Logger logger = Logger.getLogger(Run.class.getName());
      logger.log(Level.INFO, "Just logging some info");
      logger.log(Level.FINE, "Fine logging");
      logger.log(Level.FINER, "Finer logging");
      logger.log(Level.WARNING, "This is a warning log!");

    }
}

Currently when I run gradle -i test all log messages with the Level.INFO defined are shown but none of the config, warn or fine messages are output.

I've tried updating my build.gradle file such that:

apply plugin: 'java'
apply plugin:'application'
mainClassName = "Run"

repositories {
    mavenCentral()
}

dependencies {
    testCompile "junit:junit:4.11"
}

run{
    systemProperties = ['java.util.logging.config.file' : 'logging.properties']
}

I've included:

systemProperties = ['java.util.logging.config.file' : 'logging.properties']

Then created /src/main/resource/logging.propertiess

handlers= java.util.logging.ConsoleHandler
.level= CONFIG
java.util.logging.ConsoleHandler.level = FINER
java.util.logging.ConsoleHandler.formatter = java.util.logging.SimpleFormatter

Running:

gradle run

I get:

:compileJava UP-TO-DATE
:processResources UP-TO-DATE
:classes UP-TO-DATE
:run
Hello World

BUILD SUCCESSFUL

And when running gradle -i run I get: Successfully started process 'command '/Library/Java/JavaVirtualMachines/jdk1.8.0_20.jdk/Contents/Home/bin/java'' Hello World :run (Thread[main,5,main]) completed. Took 0.202 secs.

BUILD SUCCESSFUL

ie. no logging information. However commenting out the system.properties from within the run task and re-running gradle -i run I get:

Successfully started process 'command '/Library/Java/JavaVirtualMachines/jdk1.8.0_20.jdk/Contents/Home/bin/java''
Hello World
Nov 05, 2014 12:07:42 PM Run main
INFO: Just logging some info
Nov 05, 2014 12:07:42 PM Run main
WARNING: This is a warning log!
:run (Thread[main,5,main]) completed. Took 0.229 secs.

BUILD SUCCESSFUL

The info and warning level logs, but not the fine or finer ones.

tldr;

How do I get the config, fine & finer level logs to log to the console in a generic gradle java project ?

Answer 1

Several options (I personally prefer option 2.2):

1) Custom logging.properties file:

The Java Logging API has a default logging configuration file at <JRE_HOME>/lib/logging.properties. You can use your own config file setting the JVM property java.util.logging.config.file.

handlers = java.util.logging.ConsoleHandler

Run.handlers = java.util.logging.ConsoleHandler
Run.level = FINER
Run.useParentHandlers = false

java.util.logging.ConsoleHandler.level = ALL
java.util.logging.ConsoleHandler.formatter = java.util.logging.SimpleFormatter

You have to set useParentHandlers = false to avoid getting duplicate prints from parent handlers.

1.1) Set above property with absolute path

Did not even try ;-)

1.2) Load custom file as follows in Run.java

Loading it as follows in Run.java:

    InputStream inputStream = Run.class.getResourceAsStream("mylogging.properties");
    try {
        LogManager.getLogManager().readConfiguration(inputStream);
    } catch(Exception e) {
        e.printStackTrace();
    }

2) Custom system property (i.e.: logLevel)

Define a systemProperty in your build.gradle:

run {
    systemProperty 'logLevel', System.getProperty('logLevel')
}

Add a defaultLogLevel in Run.java:

public static Level defaultLevel = Level.INFO;

Get the value of logLevel property:

String logLevel = System.getProperty("logLevel");

And set the defined level in logger:

Logger logger = Logger.getLogger(Run.class.getName());
logger.setLevel(logLevel.isEmpty() ? defaultLevel : Level.parse(logLevel));

2.1) Create a new ConsoleHandler and switch-off print from parent handlers

    System.out.println(Run.class.getName());
    Logger logger = Logger.getLogger(Run.class.getName());
    logger.setLevel(logLevel.isEmpty() ? defaultLevel : Level.parse(logLevel));

    Handler consoleHandler = new ConsoleHandler();
    consoleHandler.setLevel(logLevel.isEmpty() ? defaultLevel : Level.parse(logLevel));
    logger.addHandler(consoleHandler);

    logger.setUseParentHandlers(false);

2.2) Find parent ConsoleHandler and set defined level

    Logger topLogger = Logger.getLogger("");

    Handler consoleHandler = null;
    for (Handler handler : topLogger.getHandlers()) {
        if (handler instanceof ConsoleHandler) {
            //found the console handler
            consoleHandler = handler;
            break;
        }
    }

    if (consoleHandler == null) {
        // not found, create a new one
        consoleHandler = new ConsoleHandler();
        topLogger.addHandler(consoleHandler);
    }
    //set the console handler level
    consoleHandler.setLevel(logLevel.isEmpty() ? defaultLevel : Level.parse(logLevel));

With that, gradle run yields messages above the default level (INFO). With

gradle run -DlogLevel=FINE

you can control which messages are shown.