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Spring Data Context - lookup placeholder variables from Java map, not properties file

Currently in my data context XML file, it's looking up values to substitute from a application.properties file:
<bean id="applicationProperties" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer" lazy-init="default">
<property name="location" value="classpath:application.properties" />
</bean>
<bean id="appleDataSource" class="org.apache.commons.dbcp2.BasicDataSource">
<property name="url" value="${apple.url}" />
</bean>
I'd like to change this from being looked up from the application.properties file, to being read out of a Properties/Map object.
This is because the configuration could come from more than one place (i.e. not just the classpath), and this logic is already implemented in my application.
I've seen MapPropertySource but I think while that can be done when the bean is configured in Java, I'm not sure this logic can be implemented when working with the XML file alone?

Spring Context: It's possible to define variables (not properties) in a XML and use it in runtime to obtain specific referenced beans?

I don't have much experience working with Spring Context and I don't know if this is possible...I'm trying to set into a Spring XML file a variable to define a bean reference (not a property).
Now I have a specidific xml:
keyIntegrator-key1.xml
<import resource="classpath:/events/key-events.xml" />
<context:annotation-config />
<bean id="keyIntegrator" class="com.emulated.KeySimulator" >
<property name="readList">
<list>
<bean class="com.emulated.ListEventGenerator">
<property name="eventList">
<ref bean="key-1-ok"/>
</property>
</bean>
</list>
</property>
</bean>
All the keys were defined in another xml file (key-events.xml).
I have to load in Java runtime the bean "keyIntegrator" with only one key, that is a input parameter in the Java program (I use the param to decide the xml file to load)
My question is if it's possible to define a variable inside the xml file and get the referenced bean using this variable:
Something like this:
keyIntegrator-generic.xml
<import resource="classpath:/events/key-events.xml" />
<context:annotation-config />
<bean id="keyIntegrator" class="com.emulated.KeySimulator" >
<property name="readList">
<list>
<bean class="com.emulated.ListEventGenerator">
<property name="eventList">
<ref bean="key-{inputKeyParam}-ok"/>
</property>
</bean>
</list>
</property>
</bean>
In the Java program I will need to pass the param to get the bean, something like this:
keySimulatorBean = (KeySimulator) context.getBean("keyIntegrator", "1");
There any way possible to make this ?
Thank you very much!

Thank you very much, it worked for me :)
I setted the system property value in the Java code:
System.setProperty("inputKeyParam", "1");

It is possible to do using Spring Expression Language.
For example reference to the bean can be defined using system property
<ref bean="key-#{systemProperties.inputKeyParam}-ok"/>
It will allow to reference different beans depending on provided VM option value, e.g. -DinputKeyParam=1

Conditional initialization of classes in spring

I have a service which refers to a single source.
<bean id="XYZService" class="com.services.impl.DataService1">
<constructor-arg ref="DataSource1" />
</bean>
<bean id="DataSource1" class="com.source.impl.DataSource1">
<constructor-arg ref="DBDataSource"/>
<constructor-arg value="xyz"/>
</bean>
<bean id="DataSource2" class="com.source.impl.DataSource2">
<constructor-arg ref="MsgDataSource"/>
<constructor-arg value="xyz"/>
</bean>
Now if i want to perform a conditional check and my service should be able listen to particular source based on a input variable something like below.
<bean id="XYZService" class="com.services.impl.DataService1">
<constructor-arg ref=" $VARIABLE == true ? DataSource1 : DataSource2" />
</bean>
I did tried SPEL however no luck. I am beginner in spring. Any help will be appreciated.
Thanks.

There are many solutions. Here are two: You can use profiles for this. Define two profiles, define the DataSource beans with the same name but different profiles. (docs)
Alternatively, you can use a single bean and a static factory method (docs).
<bean id="DataSource" class="com.source.impl.DataSourceFactory"
factory-method="createInstance"/>
Inside of DataSourceFactory.createInstance(), you can check the flag and then create the correct data source in plain Java.
The latter is a bit easier to understand, IMO. Using profiles allows you to keep everything in XML (but you should really consider switching to the Java Configuration). The drawback with profiles is that you must not forget to activate at least one of the bean won't be defined.
A third option is to use three XML files and then modify the list of XML files that should be parsed when you pass it to the ApplicationContext. But that only works if you have control over this part of the code.

Assuming you are using Spring 3.1 or later, Spring Profiles may be the best solution.
Using the example of Production and Dev/QA environments, common bean declarations go in a shared file
<beans>
<bean id="XYZService" class="com.services.impl.DataService1">
<constructor-arg ref="DataSource" />
</bean>
</beans>
A separate configuration contains production references
<beans profiles="prod">
<bean id="DataSource" class="com.source.impl.DataSource1">
<constructor-arg ref="DBDataSource"/>
<constructor-arg value="xyz"/>
</bean>
</beans>
Another contains dev references
<beans profile="dev">
<bean id="DataSource" class="com.source.impl.DataSource2">
<constructor-arg ref="MsgDataSource"/>
<constructor-arg value="xyz"/>
</bean>
</beans>
To activate the given profile add -Dspring.profiles.active=prod to your JVM arguments
You can find more info here
Another approach uses factory methods.
<bean id="DataSource" class="com.source.impl.DataSourceFactory" factory-method="getInstance">
<constructor-arg value="#{VARIABLE}" />
</bean>
The above fragment assumes that you want your factory method to explcitly invoke the constructor of each of your services. If you dead set on using Spring to create the instances you can pass each datasource implementation as constructor arguments and use the constructor method as a simple dispatcher.

You need something like this:
<constructor-arg
ref="#{systemProperties.variable == 'true' ? 'DataSource1' : 'DataSource2'}" />
where "variable" is set like -Dvariable=true.

Is it possible to specify a context property placeholder at runtime

I have a standalone jar that uses spring. The config in my spring xml uses placeholders of which I've been replacing when compiling with maven. Example spring config:
<bean id="foo" class="package.Foo">
<property name="host" value="${db.host}" />
</bean>
Instead of replacing ${db.host} using maven I'd like to pass in a properties file at runtime, e.g.
java -jar Application.jar productionDB.properties
This would allow me to switch the db host at runtime by passing in the production db properties file or the testing db properties file.
Is it possible to do this or are there any better ways of achieving the same goal?

You could specify your property file as a System Property, e.g.:
java -jar Application.jar -DappConfig=/path/to/productionDB.properties
Then you should be able to reference that in your application context:
<context:property-placeholder location="file:${appConfig}"/>
<bean id="foo" class="package.Foo">
<property name="host" value="${db.host}" />
</bean>

You could use a PropertyPlaceholderConfigurer to use a .properties file to pass in the required variables.
<bean id="placeholderConfig"
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
<list>
<value>classpath:productionDB.properties</value>
</list>
</property>
</bean>
You can leave your bean declaration as is. The properties will be automatically taken from the productionDB.properties file.

There are a few options:
Set your resources via your container's JNDI and use Spring's <jee:jndi-lookup/>.
Use Spring's <context:property-placeholder location="classpath:/myProps.properties" />. I prefer this short-hand over the "full" bean definition because Spring will automatically use the correct implementation (PropertyPlaceholderConfigurer for Spring < 3.1, or PropertySourcesPlaceholderConfigurer for Spring 3.1+). Using this configuration, you would just drop the myProps.properties at the root of your classpath (${TOMCAT_HOME}/lib for example).

You can pass the values using the context:property-placeholder. So your setup would be something like:
<context:property-placeholder location="file://opt/db.properties"/>
Then when you are wiring up your Foo service, you can use the property names in your config, such as
<bean id="foo" class="package.Foo">
<property name="host" value="${db.host}" />
</bean>
Then just use the different set of files for each environmnet
See the spring docs for more details.

Can one Spring PropertyPlaceholderConfigurer configure another one?

I have a PropertyPlaceholderConfigurer like this:
<bean id="propertyPlaceholderConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="ignoreUnresolvablePlaceholders" value="true"/>
<property name="locations">
<list>
<value>classpath:assuredlabor/margarita-${runningMode}.properties</value>
</list>
</property>
</bean>
I would like to be able to specify my running mode in web.xml like this:
<context-param>
<param-name>runningMode</param-name>
<param-value>production</param-value>
</context-param>
So I put this bean ABOVE the 'main' property bean I described above:
<bean id="servletPropertyPlaceholderConfigurer" class="org.springframework.web.context.support.ServletContextPropertyPlaceholderConfigurer">
</bean>
But that doesn't seem to work.
Is this possible with Spring? I am using version 2.5 right now.
I found this similar question:
PropertyPlaceholderConfigurer with Tomcat & ContextLoaderListener
But there is no discussion of the ServletContextPropertyPlaceholderConfigurer, so I think it is a legitimate question.

You can't do this in spring 2, without some custom coding I don't think, since one property placeholder cannot configure another.
You need to use spring 3 to get this out of the box. To accomplish this, you have to create a bean that somehow has the value you want, and use spring-el to reference that spring when setting up your property placeholder. There's a special bean for getting individual servlet context parameters as show below:
<bean id="runningMode" class="org.springframework.web.context.support.ServletContextAttributeFactoryBean">
<property name="attributeName" value="runningMode" />
</bean>
<bean id="propertyPlaceholderConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="ignoreUnresolvablePlaceholders" value="true"/>
<property name="locations">
<list>
<value>classpath:assuredlabor/margarita-#{runningMode}.properties</value>
</list>
</property>
</bean>
And then you can just refer to any of the properties in the normal ${} syntax

From the source code:
Subclass of PropertyPlaceholderConfigurer that resolves placeholders as ServletContext init parameters (that is, web.xml context-param entries).
Can be combined with "locations" and/or "properties" values in addition to web.xml context-params. Alternatively, can be defined without local properties, to resolve all placeholders as web.xml context-params (or JVM system properties).
If a placeholder could not be resolved against the provided local properties within the application, this configurer will fall back to ServletContext parameters. Can also be configured to let ServletContext init parameters override local properties (contextOverride=true).
Optionally supports searching for ServletContext attributes: If turned on, an otherwise unresolvable placeholder will matched against the corresponding ServletContext attribute, using its stringified value if found. This can be used to feed dynamic values into Spring's placeholder resolution.
If not running within a WebApplicationContext (or any other context that is able to satisfy the ServletContextAware callback), this class will behave like the default PropertyPlaceholderConfigurer. This allows for keeping ServletContextPropertyPlaceholderConfigurer definitions in test suites.
As I understand it, that implies that you can use just a single configurer:
<bean id="propertyPlaceholderConfigurer" class="org.springframework.web.context.support.ServletContextPropertyPlaceholderConfigurer">
<property name="ignoreUnresolvablePlaceholders" value="true"/>
<property name="locations">
<list>
<value>classpath:assuredlabor/margarita-${runningMode}.properties</value>
</list>
</property>
</bean>