createItem.groovy

@Grab('org.codehaus.groovy.modules.http-builder:http-builder:0.5.2' )
import groovyx.net.http.HTTPBuilder
import static groovyx.net.http.ContentType.*

def jobName = 'hello2'
def contentXml = '''
<?xml version='1.0' encoding='UTF-8'?>
<project>
  <actions/>
  <description></description>
  <keepDependencies>false</keepDependencies>
  <properties/>
  <scm class="hudson.scm.NullSCM"/>
  <canRoam>true</canRoam>
  <disabled>false</disabled>
  <blockBuildWhenDownstreamBuilding>false</blockBuildWhenDownstreamBuilding>
  <blockBuildWhenUpstreamBuilding>false</blockBuildWhenUpstreamBuilding>
  <triggers class="vector"/>
  <concurrentBuild>false</concurrentBuild>
  <builders>
    <hudson.tasks.Shell>
      <command>echo hello</command>
    </hudson.tasks.Shell>
  </builders>
  <publishers/>
  <buildWrappers/>
</project>
'''

def http = new HTTPBuilder("http://localhost:8080")
http.post(requestContentType:XML, path:'createItem', query:[name: jobName], body:contentXml) { res ->
    println "Done!"
}