How do I use Spring Property Placeholder with Camel XML

We do NOT yet support the ${something} notation inside arbitrary Camel XML. For example at the time of writing this is NOT supported (due Spring limitations).

IS NOT SUPPORTED

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="
       http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd
       http://activemq.apache.org/camel/schema/spring http://activemq.apache.org/camel/schema/spring/camel-spring.xsd
    ">

  <bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"/>

  <camelContext xmlns="http://activemq.apache.org/camel/schema/spring">
    <route>
      <from uri="activemq:${someQueueName}"/>
      <to uri="mock:results"/>
    </route>
  </camelContext>

</beans>

However you can use the <endpoint/> element to define endpoints which does support the property resolving which you can then refer to by name, using the Ref component as shown below (notice the ref: in the URI):

SUPPORTED

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="
       http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd
       http://activemq.apache.org/camel/schema/spring http://activemq.apache.org/camel/schema/spring/camel-spring.xsd
    ">

  <bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"/>

  <camelContext xmlns="http://activemq.apache.org/camel/schema/spring">
    <endpoint id="input1" uri="activemq:${someQueueName}"/>

    <route>
      <from uri="ref:input1"/>
      <to uri="activemq:OutputQueue"/>
    </route>
  </camelContext>

</beans>

Camel does not yet fully support property placeholders as there is a limitation in Spring. See JIRA SPR-4466

Bridge Spring and Camel property placeholders

From Camel 2.10 onwards you can bridge Spring and Camel property placeholders, see Using PropertyPlaceholder for more details.

Here is a trick that you can use to define the uri in a property file using Spring injection and Camel endpoint: http://cmoulliard.blogspot.com/2009/05/trick-to-pass-uri-declared-in-property.html.

From Camel 2.3 onwards there is a Properties component build in Camel core which allows you to use properties in the same way as Spring property placeholders, and even more.