//前置处理Job创建
List<Job> pres=parseJobs(jobContext, applicationContext, jobBean,jobBean.getJobDescriptor().getPreProcessers(),history,workDir);
pres.add(0, new DownloadJob(jobContext));
//后置处理Job创建
List<Job> posts=parseJobs( jobContext, applicationContext, jobBean,jobBean.getJobDescriptor().getPostProcessers(),history,workDir);
posts.add(new ZooKeeperJob(jobContext, null, applicationContext));
//核心处理Job创建
Job core=null;
if(jobBean.getJobDescriptor().getJobType()==JobRunType.MapReduce){
core=new MapReduceJob(jobContext);
}else if(jobBean.getJobDescriptor().getJobType()==JobRunType.Shell){