conditional injection in spring

[Pradeep bhatt]

Can we have conditional injection in spring like is system property value is A, inject bean A. if the value is B inject bean B. Is such a thing possible?

[Sagar Rohankar]

I'm not sure but check whether SpEL serves your problem or not: http://static.springsource.org/spring/docs/3.0.x/reference/expressions.html

[Bill Gorder]

Do they implement a common interface?

public class MyClass
{
    private CommonInterface commonInterface;
...
}

You can do a number of things. If you are using java config just @Autowire in Springs Environment and return the bean you want

@Bean
public CommonInterface commonInterface(){
    if("myVal".equals(environment.getProperty("mySystemProperty")){
        return new Implentation1();
    }
    return new implentation2();
}

With XML you can do the same thing just use SPEL

<bean id="myBean" class="MyClass">
    <property name="commonInterface" ref="${myPropertyKey}" />
</bean

<bean id="myPropertyValue1" class="Implementation1" lazy-init="true" />
<bean id="myPropertyValue2" class="Implementation2" lazy-init="true" />

Or you could use a factory bean. You can google for the XML equivalent if you are not familiar with them
http://blog.springsource.org/2011/08/09/whats-a-factorybean

[Bill Gorder]

Just an additional note. My first 2 options assume the use of a PropertyPlaceholderConfigurer or if you are using spring 3.1 it should be a PropertySourcesPlaceholderConfigurer