title: in spring batch, setting job parameters in job execution listener before Job execution
body: <p>I am new spring batch.
       I am running the Job using CommandLineRunner. I have some properties in .properties file.
      for ex:</p>
  
  <pre><code> my.path=mydir_{event1}_{event2}
  </code></pre>
  
  <p>So the event1 and event2 this strings need to get replace with the runtime job parameters. As I am running Job using commandLine runner,
  I added JobExecutionListener to the Job and tried to write code in beforeJob 
  but I am not able to set the parameters from the beforeJob funciton
  Can anybody help me on this requirement.
  I want something like this.</p>
  
  <pre><code>@Override
      public void beforeJob(JobExecution jobExecution) {
      String event1= jobExecution.getJobParameters().getString("event1");
     String filepath=replace("{event1}", event1);
  
    jobExecution.getExecutionContext().put("filepath",filepath);
  }
  </code></pre>
  
  <p>.jobExecution.getExecutionContext() this doesn't work. Is there any other way to do this thing.
  It does not work means->
  after putting value inside the executioncontext. I use the the key inside spring-job-context.xml using
   <code>#{jobExecutionContext['filepath']}</code>
  So by using this way, I am not able to get the value which I have set in beforeJob function.</p>