How to configure log4j with a properties file

Question

How do I get log4j to pick up a properties file   I m writing a Java desktop app which I want to use log4j  In my main method if have this      PropertyConfigurator configure  log4j properties      The log4j properties file sits in the same directory when I open the Jar   Yet I get this error      log4j ERROR Could not read   configuration file  log4j properties     java io FileNotFoundException    log4j properties  The system cannot   find the file specified    What am I doing wrong

User · Answer

You can enable log4j internal logging by defining the  log4j debug  variable

User · Answer

I believe that the configure method expects an absolute path  Anyhow  you may also try to load a Properties object first   Properties props   new Properties    props load new FileInputStream  log4j properties     PropertyConfigurator configure props     If the properties file is in the jar  then you could do something like this   Properties props   new Properties    props load getClass   getResourceAsStream   log4j properties     PropertyConfigurator configure props     The above assumes that the log4j properties is in the root folder of the jar file

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import org apache log4j PropertyConfigurator   Import this  then  Properties props   new Properties    InputStream is   Main class getResourceAsStream  quot  log4j properties quot     try       props load is     catch  Exception e           ignore this exception     log error  quot Unable to load log4j properties file  quot  e     PropertyConfigurator configure props    My java files directory like this  src main java com abc xyz  And log4j directory like this  src main resources

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I have this code in my application today      File log4jfile   new File    conf log4j properties    PropertyConfigurator configure log4jfile getAbsolutePath       The relative path is from the working directory of the JVM  where the JVM starts

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When you use PropertyConfigurator configure String configFilename   they are the following operation in the log4j library    Properties props   new Properties    FileInputStream istream   null  try     istream   new FileInputStream configFileName     props load istream     istream close      catch  Exception e          It fails in reading because it looks for  Log4j properties  from the current directory where the application is executed    How about the way that it changes the reading part of the property file as follows  and puts  log4j properties  on the directory to which the CLASSPATH is set   ClassLoader loader   Thread currentThread   getContextClassLoader    URL url   loader getResource  log4j properties    PropertyConfigurator configure url     Another method of putting  Log4j properties  in the jar file exists    jar xvf  YourApplication  jar log4j properties

User · Answer

I believe the log4j properties directory it needs to be in the java classpath  In your case adding the CWD to the classpath should work

User · Answer

Since JVM arguments are eventually passed to your java program as system variables  you can use this code at the beginning of your execution point to edit the property and have log4j read the property you just set in system properties  try           System setProperty  log4j configuration   new File System getProperty  user dir   File separator  conf  File separator  log4j properties   toURI   toURL   toString           catch  MalformedURLException e            e printStackTrace

User · Answer

just set  -Dlog4j configuration file log4j properties worked for me    log4j then looks for the file log4j properties in the current working directory of the application   Remember that log4j configuration is a URL specification  so add  file   in front of your log4j properties filename if you want to refer to a regular file on the filesystem  i e  a file not on the classpath   Initially I specified  -Dlog4j configuration log4j properties  However that only works if log4j properties is on the classpath  When I copied log4j properties to main resources in my project and rebuild so that it was copied to the target directory  maven project  this worked as well  or you could package your log4j properties in your project jars  but that would not allow the user to edit the logger configuration

User · Answer

This is an edit of the answer from  kgiannakakis  The original code is wrong because it does not correctly close the InputStream after Properties load InputStream  is called   From the Javadocs  The specified stream remains open after this method returns                                     I believe that the configure method expects an absolute path  Anyhow  you may also try to load a Properties object first   Properties props   new Properties    InputStream is   new FileInputStream  log4j properties    try       props load is     finally       try           is close              catch  Exception e               ignore this exception         PropertyConfigurator configure props     If the properties file is in the jar  then you could do something like this   Properties props   new Properties    InputStream is   getClass   getResourceAsStream   log4j properties    try       props load is     finally       try           is close              catch  Exception e               ignore this exception         PropertyConfigurator configure props     The above assumes that the log4j properties is in the root folder of the jar file

[java] How to configure log4j with a properties file

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