Configuring Java FileHandler Logging to create directories if they do not exist

Question

I'm trying to configure the Java Logging API's FileHandler to log my server to a file within a folder in my home directory, but I don't want to have to create those directories on every machine it's running.

For example in the logging.properties file I specify:

java.util.logging.FileHandler
java.util.logging.FileHandler.pattern=%h/app-logs/MyApplication/MyApplication_%u-%g.log

This would allow me to collect logs in my home directory (%h) for MyApplication and would rotate them (using the %u, and %g variables).

Log4j supports this when I specify in my log4j.properties:

log4j.appender.rolling.File=${user.home}/app-logs/MyApplication-log4j/MyApplication.log

It looks like there is a bug against the Logging FileHandler: Bug 6244047: impossible to specify driectorys to logging FileHandler unless they exist

It sounds like they don't plan on fixing it or exposing any properties to work around the issue (beyond having your application parse the logging.properties or hard code the path needed):

It looks like the java.util.logging.FileHandler does not expect that the specified directory may not exist. Normally, it has to check this condition anyway. Also, it has to check the directory writing permissions as well. Another question is what to do if one of these check does not pass.

One possibility is to create the missing directories in the path if the user has proper permissions. Another is to throw an IOException with a clear message what is wrong. The latter approach looks more consistent.

Answer 1

It seems like log4j version 1.2.15 does it.

Here is the snippet of the code which does it

public
 synchronized
 void setFile(String fileName, boolean append, boolean bufferedIO, int bufferSize)
                                                        throws IOException {
    LogLog.debug("setFile called: "+fileName+", "+append);

    // It does not make sense to have immediate flush and bufferedIO.
    if(bufferedIO) {
      setImmediateFlush(false);
    }

    reset();
    FileOutputStream ostream = null;
    try {
          //
          //   attempt to create file
          //
          ostream = new FileOutputStream(fileName, append);
    } catch(FileNotFoundException ex) {
          //
          //   if parent directory does not exist then
          //      attempt to create it and try to create file
          //      see bug 9150
          //
          String parentName = new File(fileName).getParent();
          if (parentName != null) {
             File parentDir = new File(parentName);
             if(!parentDir.exists() && parentDir.mkdirs()) {
                ostream = new FileOutputStream(fileName, append);
             } else {
                throw ex;
             }
          } else {
             throw ex;
          }
    }
    Writer fw = createWriter(ostream);
    if(bufferedIO) {
      fw = new BufferedWriter(fw, bufferSize);
    }
    this.setQWForFiles(fw);
    this.fileName = fileName;
    this.fileAppend = append;
    this.bufferedIO = bufferedIO;
    this.bufferSize = bufferSize;
    writeHeader();
    LogLog.debug("setFile ended");
}

This piece of code is from FileAppender, RollingFileAppender extends FileAppender.

Here it is not checking whether we have permission to create the parent folders, but if the parent folders is not existing then it will try to create the parent folders.

EDITED

If you want some additional functionalily, you can always extend RollingFileAppender and override the setFile() method.