Dynamically loading name of Java class file in a Quartz job

Question

I have a Quartz job written in Java which runs fine if I have the Quartz JobDetail line set as follows:

JobDetail jd = new JobDetail("FeedMinersJob", scheduler.DEFAULT_GROUP, FeedMinersScheduler.class);

But I would like to dynamically load the class because the job details are stored in a database table. So I want something like this:

JobDetail jd = new JobDetail(sj.getJobName(), scheduler.DEFAULT_GROUP, sj.getJobClassFile());

Where sj is a scheduled job object and method sj.getJobClassFile() returns the name of the class defined in sj instead of having the class name hardcoded.

I've tried permutations of the Java Class.forName method but without success.

Answer 1

As I understand it, you code should like this:

Class<?> jobClass = Class.forName(sj.getJobClassFile());
JobDetail jd = new JobDetail(sj.getJobName(), scheduler.DEFAULT_GROUP, jobClass);

Can you please post the code snippets which didn't work?

Answer 2

There are two lines of code which work as there are below:

JobDetail jd = new JobDetail(sj.getJobName(), scheduler.DEFAULT_GROUP, FeedMinersScheduler.class); 
CronTrigger ct = new CronTrigger(sj.getJobTrigger(), scheduler.DEFAULT_GROUP, "0 0/" + Integer.toString(sj.getJobIntervalMinutes()) + " * * * ?");

But obviously I want the first of these to be:

Class<?> jobClass = Class.forName(sj.getJobClassFile());
JobDetail jd = new JobDetail(sj.getJobName(), scheduler.DEFAULT_GROUP, jobClass);

But I find this doesn't work either. –

Answer 3

Try this

try {
    Class<?> jobClass = Class.forName(sj.getJobClassFile());
    JobDetail jd = new JobDetail(sj.getJobName(), scheduler.DEFAULT_GROUP, jobClass);
} catch (ClassNotFoundException e) {
    // put here some error handling
}

And if it doesn't work please give more details about the problem - compilation error, exception in runtime or some other problem.

Answer 4

I have this, maybe it will be usefull to you: (getClassName() returns a string)

Class<?> jobClass = Class.forName(t_job.getClassName());
if (Job.class.isAssignableFrom(jobClass)) {
        // create a job detail that is not volatile and is durable (is persistent and exists without trigger)
        JobDetail job = new JobDetail(t_job.getName(), t_job.getGroupName(), jobClass, false, true, true);
        job.setDescription(t_job.getDescription());

}