Java – Log4j Log is not created when jar file run

javalog4j

This is my Student class that used to test log4j.

public class Student{    
    private static final Logger logger = Logger.getLogger(Student.class.getName());   

    public Student() {  
         PropertyConfigurator.configure("log4j.properties");  
    }

    public static void main(String args[]){  
        logger.log(Level.INFO, "My log4j Test");    
    } 
}

This is my log4j.properties file

log4j.rootLogger=INFO,Appender1,Appender2
log4j.appender.Appender1=org.apache.log4j.ConsoleAppender
log4j.appender.Appender2=org.apache.log4j.RollingFileAppender
log4j.appender.Appender2.File=C:/Log4j/MyLogExample.log

log4j.appender.Appender1.layout=org.apache.log4j.PatternLayout`  
log4j.appender.Appender1.Target=System.out`   
log4j.appender.Appender1.layout.ConversionPattern=%-4r [%t] %-5p %c %x - %m%n`  

log4j.appender.Appender2.layout=org.apache.log4j.PatternLayout`  
log4j.appender.Appender2.layout.ConversionPattern=%-4r [%t] %-5p %c %x - %m%n`  

log4j.appender.Appender2.MaxFileSize=50KB`  
log4j.appender.Appender2.MaxBackupIndex=10`

When I run this program using Eclipse MyLogExample.log file gets created. But after I have created a jar file and run it using the command prompt, the log file is not created.

in console i can see this error.

log4j:ERROR Could not read configuration file [log4j.properties]. 
java.io.FileNotFoundException: log4j.properties (The system cannot find the file specified)

After I add the following code example, the log file is created even when the jar file run with command prompt.

PropertyConfigurator.configure("C:\\eclipeworkspace\\Log4jTest\\log4j.properties");

How I can give relative path instead of exact path?

Best Answer

Use this :

ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
URL url = classLoader.getResource("log4j.properties");
File file = new File(url.toURI());

Related Solutions

Java – Can’t execute jar- file: “no main manifest attribute”

First, it's kind of weird, to see you run java -jar "app" and not java -jar app.jar

Second, to make a jar executable... you need to jar a file called META-INF/MANIFEST.MF

the file itself should have (at least) this one liner:

Main-Class: com.mypackage.MyClass

Where com.mypackage.MyClass is the class holding the public static void main(String[] args) entry point.

Note that there are several ways to get this done either with the CLI, Maven, Ant or Gradle:

For CLI, the following command will do: (tks @dvvrt)

jar cmvf META-INF/MANIFEST.MF <new-jar-filename>.jar  <files to include>

For Maven, something like the following snippet should do the trick. Note that this is only the plugin definition, not the full pom.xml:

Latest doc on this plugin: see https://maven.apache.org/plugins/maven-jar-plugin/

<build>
  <plugins>
    <plugin>
      <!-- Build an executable JAR -->
      <groupId>org.apache.maven.plugins</groupId>
      <artifactId>maven-jar-plugin</artifactId>
      <version>3.1.0</version>
      <configuration>
        <archive>
          <manifest>
            <addClasspath>true</addClasspath>
            <classpathPrefix>lib/</classpathPrefix>
            <mainClass>com.mypackage.MyClass</mainClass>
          </manifest>
        </archive>
      </configuration>
    </plugin>
  </plugins>
</build>

(Pick a <version> appropriate to your project.)

For Ant, the snippet below should help:

<jar destfile="build/main/checksites.jar">
  <fileset dir="build/main/classes"/>
  <zipfileset includes="**/*.class" src="lib/main/some.jar"/>
  <manifest>
    <attribute name="Main-Class" value="com.acme.checksites.Main"/>
  </manifest>
</jar>

Credits Michael Niemand -

For Gradle:

plugins {
    id 'java'
}

jar {
    manifest {
        attributes(
                'Main-Class': 'com.mypackage.MyClass'
        )
    }
}

Java – log4j.properties configuration

Try assignining root logger as FATAL and divert the log to a dummy file :

    log4j.rootLogger=FATAL, fatalFile
    log4j.appender.fatalFile=org.apache.log4j.RollingFileAppender
    log4j.appender.fatalFile.file=log/fatal.log
    log4j.appender.fatalFile.MaxFileSize=10MB
    log4j.appender.fatalFile.MaxBackupIndex=10
    log4j.appender.fatalFile.layout=org.apache.log4j.PatternLayout
    log4j.appender.fatalFile.layout.conversionPattern=%d{[dd.MM.yyyy] [HH:mm:ss]} %p [%t] %c (%F:%L) - %m%n

and add console appender in log4j.logger.infoNTS as:

log4j.logger.infoNTS=DEBUG, file, nConsole
log4j.appender.file=org.apache.log4j.RollingFileAppender
log4j.appender.file.file=log/spider.cisco.log
log4j.appender.file.MaxFileSize=1GB
log4j.appender.file.MaxBackupIndex=10
log4j.appender.file.layout=org.apache.log4j.PatternLayout
log4j.appender.file.layout.conversionPattern=%d{[dd.MM.yyyy] [HH:mm:ss]} %p [%t] %c (%F:%L) - %m%n

log4j.appender.nConsole= org.apache.log4j.ConsoleAppender
log4j.appender.nConsole.target=System.out
log4j.appender.nConsole.layout = org.apache.log4j.PatternLayout
log4j.appender.nConsole.layout.ConversionPattern = %d{[dd.MM.yyyy] [HH:mm:ss]} %p [%t] %c (%F:%L) - %m%n

Best Answer

Related Solutions

Java – Can’t execute jar- file: “no main manifest attribute”

Java – log4j.properties configuration

Related Topic