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Suggestion to implement custom bean initialization/creation logic in Spring

In my Java/spring project there are lots of beans configured in an xml like,
<beans>..
<bean id="beanOne" class=...>
<property name="x" value="1"/>
<property name="y" value="something"/>
<property name="z" value="something else"/>
</bean>
</beans>
"beanOne"'s properties(x,y,z) values keep changing for different needs/machines. I can create different xml files having different values, one for each need/machine. But I want to write some custom bean creation logic so that I can define different properties in a single properties (or) json file and the custom class takes care of creating the beans with appropriate values from that single properties (or) json file for all needs/machines.
So how to can I do that in spring? - Extend AbstractFactoryBean, implement FactoryBean, implement BeanFactory, or something else? I just need the logic/skeleton of how to do that using spring.

Follow these steps to do the same,
create the object for your required bean.
Set the required properties for that object, you can fetch it from anywhere you want.
Register that object in beanFactory as a bean.
Reference : https://wordpress.com/post/anilagrawal038.wordpress.com/3

Auto-wiring Spring constructor arguments from properties file in XML

I'm using Spring to auto-wire beans for configuration. Some parameters come from a properties file:
<bean id="mydb" class="myproject.mydb" autowire="constructor">
<constructor-arg name="host" value="${mydb.host}" />
<constructor-arg name="db" value="${mydb.db}" />
<constructor-arg name="user" value="${mydb.user}" />
<constructor-arg name="password" value="${mydb.password}" />
</bean>
Is there a way to auto-wire these properties based on the bean id so that I would just have to write the following?
<bean id="mydb" class="myproject.mydb" autowire="constructor" />
Edit: The point of this is to not have to explicity specify the non-bean constructor arguments. I want Spring to automatically check the properties for beanId.constructorArgName

To achieve exactly what you want, I think you'd need to implement a BeanPostProcessor and provide your custom wiring logic (where you read the .properties file) in postProcessBeforeInitialization. The bean name is available to that method, but there are multiple problems with this. The first is that argument names are not necessarily available at runtime, so indexes might be a better option. The second is that you already have an instantiated bean (so a default constructor would need to exists), and you'd instantiate another, throwing the first one away which is wasteful. To use the instance that already exists, you'd need to wire it by properties, not constructor, which violates encapsulation and is not what you asked. The third is that it's not at all obvious what is going on. So, all in all, you are probably better off avoiding this completely.

In your class myproject.mydb
#Autowired
public mydb(#Value("mydb.host") String host, ...){...}

As per your question, the only way Property values can be injected to the constructor is through the XMLfile as done above or using the #Value("${some.property}") annotation.
Refer this for more info

Use #Value("property key") annotation. look at eg.: http://java.dzone.com/articles/autowiring-property-values

Spring - PropertyOverrideConfigurer multiple configuration lines for ONE bean property

I have a spring xml file with some beans, two of which I have pasted below:
<bean
class="org.springframework.beans.factory.config.PropertyOverrideConfigurer">
<property name="locations">
<value>classpath:projectname-override.properties</value>
</property>
</bean>
<bean id="myBeanName"
class="my.company.department.svc.spring.WmSvcJndiDataSource">
<property name="jndiName">
<value>jdbc/XXXXX</value>
</property>
<property name="jndiTemplate">
<ref bean="myJndiTemplate" />
</property>
</bean>
The properties file referred to in the first bean is very small (currently only one line), and looks like this:
myBeanName.jndiName=java:comp/env/jdbc/XXXXX_YYY_DEV3
It is my understanding that PropertyOverrideConfigurer in the first bean
pushes values from a properties file into bean definitions
So the value of the jndiName property in the myBeanName bean will turn from
jdbc/XXXXX
to
java:comp/env/jdbc/XXXXX_YYY_DEV3.
This works and it partially does what we want. I need to expand the functionality so that I can handle multiple deployment environments. This currently replaces the bean property for one of our development environments (dev3). I think I need spring to dynamically alter "myBeanName" for about 25 different dev environments.
For example, I think I want my properties file to look like this
myBeanName.jndiName=java:comp/env/jdbc/XXXXX_YYY_DEV1
myBeanName.jndiName=java:comp/env/jdbc/XXXXX_YYY_DEV2
myBeanName.jndiName=java:comp/env/jdbc/XXXXX_YYY_DEV3
myBeanName.jndiName=java:comp/env/jdbc/XXXXX_YYY_DEV4
myBeanName.jndiName=java:comp/env/jdbc/XXXXX_YYY_DEV5
...
...
myBeanName.jndiName=java:comp/env/jdbc/XXXXX_YYY_DEV24
myBeanName.jndiName=java:comp/env/jdbc/XXXXX_YYY_DEV25
I have no idea if this is the right approach.
Any ideas?
Thanks in advance.
NOTE
my.company.department.svc.spring.WmSvcJndiDataSource in the second bean is simply a class we extended off of org.springframework.jndi.JndiObjectFactoryBean, FYI. I don't know if that is important to know or not.

conditional beans using spring

I am trying to write a ValidatorFactory which will give me a validator based on its type
public Validator getNewValidator(ValidatorType type){
switch:
case a : new Validator1();
break;
case b : new Validator2();
break;
}
I want to write using spring xml beans definition
I can use method injection but it will let me create only one object and the method does
not take any arguments.
I don't want to use FactoryBean.. I am just looking whether we can do this using spring xml
bean definition.

you can do conditional bean injection with plain xml. The "ref" attribute can be triggered by property values from a property file and thus create conditional beans depending on property values. This feature is not documented but it works perfect.
<bean id="validatorFactory" class="ValidatorFactory">
<property name="validator" ref="${validatorType}" />
</bean>
<bean id="validatorTypeOne" class="Validator1" lazy-init="true" />
<bean id="validatorTypeTwo" class="Validator2" lazy-init="true" />
And the content of the property file would be:
validatorType=validatorTypeOne
To use the property file in your xml just add this context to the top of your spring config
<context:property-placeholder location="classpath:app.properties" />

For complex cases (more complex than the one exposed), Spring JavaConfig could be your friend.

If you are using annotation (#Autowired, #Qualifier etc) instead of xml, you are not able to make conditional beans work (at least at current version 3). This is due to #Qualifier does not support expression
#Qualifier(value="${validatorType}")
More information is at https://stackoverflow.com/a/7813228/418439

I had an slightly different requirements. In my case I wanted to have encoded password in production but plain text in development. Also, I didn't have access to parent bean parentEncoder. This is how I managed to achieve that:
<bean id="plainTextPassword" class="org.springframework.security.authentication.encoding.PlaintextPasswordEncoder"/>
<bean id="shaPassword" class="org.springframework.security.authentication.encoding.ShaPasswordEncoder">
<constructor-arg type="int" value="256"/>
</bean>
<bean id="parentEncoder" class="org.springframework.aop.framework.ProxyFactoryBean">
<property name="targetSource">
<bean class="org.springframework.aop.target.HotSwappableTargetSource">
<constructor-arg ref="${password.encoding}Password"/>
</bean>
</property>
</bean>
Of course, I defined password.encoding in a property file with possible values as sha or plainText.

You should be able to do this:
<bean id="myValidator" factory-bean="validatorFactory" factory-method="getNewValidator" scope="prototype">
<constructor-arg><ref bean="validatorType"/></constructor-arg>
</bean>
<bean id="validatorType" ... />
Of course, it uses an automatically configured FactoryBean underneath but you avoid any Spring dependency in your code.

How do I inject a single property value into a string using spring 2.5.x?

I would really like to annotate a method with a reference to a single property in a property file for injection.
#Resource("${my.service.url}")
private String myServiceUrl;
Of course, this syntax does not work ;) Thats why I'm asking here.
I am aware that I can inject the full properties file, but that just seems excessive, I dont want the property file - I want the configured value.
Edit: I can only see PropertyPlaceholderConfigurer examples where XML is used to wire the property to the given field. I still cannot figure out how this can be achieved with an annotation ?

I know it has been a while since the original post but I have managed to stumble across a solution to this for spring 2.5.x
You can create instances of "String" beans in the spring xml configuration which can then be injected into the Annotated components
#Component
public class SomeCompent{
#Autowired(required=true
#Resource("someStringBeanId")
private String aProperty;
...
}
<beans ....>
<context:component-scan base-package="..."/>
<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
...
</bean>
<bean id="someStringId" class="java.lang.String" factory-method="valueOf">
<constructor-arg value="${place-holder}"/>
</bean>
</beans>

I've created a project which addresses this problem for Spring 2.5.*:
http://code.google.com/p/spring-property-annotations/
For Spring 3 you can use the #Value("${propery.key}") annotation.

There's a thread about this on the Spring forum. The short answer is that there's really no way to inject a single property using annotations.
I've heard that the support for using annotations will be improved in Spring 3.0, so it's likely this will be addressed soon.

you can do this if you use XML configuration. Just configure PropertyPlaceholderConfigurer and specify property value in configuration
<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
<value>classpath:com/foo/jdbc.properties</value>
</property>
</bean>
<bean ...>
<property name="myServiceUrl" value="${my.service.url}"/>
</bean>

You could try injecting value of property "my.service.url" to a filed in your bean.
Take a look at: http://static.springframework.org/spring/docs/2.5.x/reference/beans.html#beans-factory-placeholderconfigurer
HTH.