How to access Grails configuration in Grails 2.0?

I have obtained the latest Grails 2.0 milestone, and I am seeing a deprecation warning for the ConfigurationHolder class:

org.codehaus.groovy.grails.commons.ConfigurationHolder

The deprecation message simply says "Use dependency injection instead" which is not very helpful to me. I understand dependency injection, but how can I wire up a bean with the proper Grails configuration so I can access it at runtime? I need to access the configuration from places other than my Controllers and Tags (such as BootStrap).

• If you need it in an artifact that supports dependency injection, simply inject grailsApplication

  class MyController {
      def grailsApplication
  
      def myAction = {
          def bar = grailsApplication.config.my.property
      }
  }
  

• If you need it in a bean in, say, src/groovy or src/java, wire it up using conf/spring/resources.groovy

  // src/groovy/com/example/MyBean.groovy
  class MyBean {
      def grailsApplication
  
      def foo() {
          def bar = grailsApplication.config.my.property
      }
  }
  
  // resources.groovy
  beans = {
      myBean(com.example.MyBean) {
          grailsApplication = ref('grailsApplication')
          // or use 'autowire'
      }
  }
  

• Anywhere else, it's probably easiest to either pass the configuration object to the class that needs it, or pass the specific properties that are needed.

  // src/groovy/com/example/NotABean.groovy
  class NotABean {
      def foo(def bar) {
         ...
      }
  }
  
  // called from a DI-supporting artifact
  class MyController {
      def grailsApplication
      def myAction = {
          def f = new NotABean()
          f.foo(grailsApplication.config.my.property)
      }
  }
  

Update:

Burt Beckwith recently wrote a couple of blog posts on this. One discusses using getDomainClass() from within domain classes, while the other offers the option of creating your own holder class (if none of the solutions above are appropriate).

An alternative to grailsApplication is the Holders class,

import grails.util.Holders

def config = Holders.config

You get config directly off of Holders, no injection needed, which is nice for utility classes, etc.

you can inject "grailsApplication" into your source file. here is a sample conf/Bootstrap.groovy

class BootStrap {

    def grailsApplication

    def init = { servletContext ->
        println grailsApplication.config
    }

    def destroy = {
    }
}

Another non-deprecated way to get the config is:

    ApplicationContext context = ServletContextHolder.servletContext.
        getAttribute(GrailsApplicationAttributes.APPLICATION_CONTEXT) 
        as ApplicationContext
    ConfigObject config = context.getBean(GrailsApplication).config

This works in situations where there is no injected parent available, such as servlet classes or static methods.