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What I am going to do here is create a simple HelloWorld application with a few lines which get logged using Apache-commons logging facade and Log4J providing the actual logging implementation. The sample assumes that you have JDK 1.7+ and Gradle installed correctly on your system.
My working directory will be /home/siddharth/Temp/GradleTest. All files and folders mentioned will be created within this directory. For this project, I will use the standard folder structure required by Gradle. The following folders need to be created under GradleTest:
GradleTest
+- src
+- main
+- java
+- resources
Let's create the build.gradle file under GradleTest directory which will be used by Gradle to build the project. The contents of this file is:
apply plugin: 'java'
repositories{
mavenCentral()
}
dependencies {
compile 'log4j:log4j:1.2.17'
compile 'commons-logging:commons-logging:1.2'
}
jar {
from { configurations.compile.collect { it.isDirectory() ? it : zipTree(it) } }
manifest {
attributes 'Main-Class': 'Sample'
}
}
The java-plugin supports a number of tasks which are mentioned here. Now that we have the instructions for gradle ready lets create the HelloWorld program.
Create a file named 'Sample.java' within GradleTest/src/main/java. The content of this file is:
import java.lang.*;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
public class Sample {
final static Log logger = LogFactory.getLog(Sample.class);
public static void main(String[] args) {
logger.debug("main start");
System.out.println("Hello Siddharth");
logger.debug("main end");
}
}
Create a text file named 'log4j.properties' in the GradleTest/src/main/resources directory. This file is used to configure the behavior of Log4J. The content of this file is below:
# Root logger option
log4j.rootLogger=DEBUG, stdout, file
# Redirect log messages to console
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n
# Redirect log messages to a log file, support file rolling.
log4j.appender.file=org.apache.log4j.RollingFileAppender
log4j.appender.file.File=$HOME
log4j.appender.file.MaxFileSize=5MB
log4j.appender.file.MaxBackupIndex=10
log4j.appender.file.layout=org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n
We are now all set to build the project. Open a terminal window (command prompt in Windows). Navigate to the GradleTest folder, for me this is /home/siddharth/Temp/GradleTest. Type in:
gradle assemble
This will build the project. Since we have mentioned Apache-commons and Log4J as dependencies, these will be downloaded as part of the build process; you'll need to be connected to the WWW. The output of the build process should look something like this:
Lets now test if everything got built as it should have by running the code. While in the GradleTest directory, type in:
> java -cp build/libs -jar build/libs/GradleTest.jar
You should see the output of the program.
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