How to manage hadoop job submit?

[WangRamon]

Hi All  
I'm new to hadoop, I know I can use "haddop jar" to submit my M/R job, but we 
need to submit a lot of jobs in my real environment, there is priority 
requirement for each jobs, so is there any way to manage how to submit jobs? 
Any Java API? Or we can only use the hadoop command line with shell or python 
to do the job submit?  
Thanks Ramon