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Session scoped hashmap in Spring

I'm trying to learn pure Spring and to do that i'm converting my Spring-boot application to spring with pure xml configuration.
My question is how can I obtain session scoped property through xml configuration?
Right now i've got this:
#Autowired
private
ConcurrentHashMap<String,Subscription> subscriptionConcurrentHashMap;
(...)
#Bean
#SessionScope
private ConcurrentHashMap<String, Subscription> getConcurrentHashMap(){
return new ConcurrentHashMap<>();
}
And it works, but i'm not sure how to define generic java class as session scoped bean in xml.

I've found a way to this like that:
<bean name="subscriptionConcurrentHashMapBean" class="java.util.concurrent.ConcurrentHashMap" scope="session">
<aop:scoped-proxy/>
</bean>
and then just reference in controller bean:
<property name="subscriptionConcurrentHashMap" ref="subscriptionConcurrentHashMapBean"/>
Generic type of this hashMap apparently doesn't matter

Loading a Map in field of Class Object, before the Class instance is returned by getBean method of Spring?

I have a .properties file having 10 key-values pairs say age =10, name=Jon etc. I have configured a bean in spring which has a map as a member variable.
When the bean is loaded by Spring once I call the getBean method, before that the Map should be loaded with the properties from files. How to do that ?
I know this should be done in one of the lifecycle methods like afterPropertiesSet using InitializingBean or init-method configuration. Is there any other better way to do this ?

You can enable annotations in your beans:
<context:annotation-config />
Then you can define method with #PostConstruct annotation. Spring will execute it during bean initialization process:
class MyBean {
private Map<String, String> properties;
#PostConstruct
public void initialize() {
// read properties and initialize map
}
}
Another option is to inject Properties directly into your bean and provide map-like API to access them:
<util:properties id="myProperties" location="classpath:my-props.properties">
<bean id="myBean" class="com.example.MyBean">
<property name="properties" ref="myProperties" />
</bean>

you can use context property-placeholder within XML spring configuration file using ${...} or from java class configuration file using #value.

ways to inject a object of a class in spring controller?

I need to inject a object of a java class in spring controller through applicaionContext.xml. My controller will be ,
#Controller
public class SpringController{
private MyClass obj;
}
I know I can do it with #Autowired annotation.
Is this really good to create a object for a controller through applicaionContext.xml ? Also can I inject a object of a class in controller using the <property> tag inside a <bean> tag ?
Is this really possible ? or please forgive me if it is a stupid question.
I need to know the possible ways for how to inject a object of a class in Spring controller ?

You can of course use #Autowired annotation to autowire the relationships, which can reduce the need to define the properties and constructor arguments for the controller in your applicationContext.xml file. And also to add a dependency to a class, you don't need to modify the configuration files.
But it has some disadvantages too, like if you use #Autowired, there will not be any explicit documentation for the wiring details between Spring managed beans. And to know the relationships between the beans, you have to go through your managed beans. But, if you use configuration files to define the relationships, the relationship details can be found in one place.
You can inject an object of a class into your controller through your applicaionContext.xml as below:
Constructor based injection:
#Controller
public class SpringController{
private MyClass obj;
public SpringController(MyClass obj){
this.obj=obj;
}
}
<bean id="myClassImpl" class="x.y.z.MyClassImpl"></bean>
<bean id="springController" class="x.y.z.web.controllers.SpringController">
<constructor-arg ref="myClassImpl"></constructor-arg>
</bean>
Setter based injection:
#Controller
public class SpringController{
private MyClass obj;
public void setObj(MyClass obj){
this.obj=obj;
}
public MyClass getObj(){
return obj;
}
}
<bean id="myClassImpl" class="x.y.z.MyClassImpl"></bean>
<bean id="springController" class="x.y.z.web.controllers.SpringController">
<property name="obj" ref="myClassImpl"></property>
</bean>

If you want to inject an object in a controller and you particularly want to you use xml,then instead of component scanning of Controller you should create a bean of the controller class of singleton scope in the application context.
Your controller class need not be annotated with #Controller.
you then have to you extend some Controller also like AbstractCommandController, AbstractController, AbstractFormController, AbstractWizardFormController, BaseCommandController, CancellableFormController, MultiActionController SimpleFormController, UrlFilenameViewController
Now to inject a particular object you can use Either Constructor and Setter based injection.
or you can use Autowring by name or type to auto inject the object.
Make sure that you have also declared the bean of that object also in Application Context.
After a DispatcherServlet has received a request and has done its work to resolve locales, themes and suchlike, it then tries to resolve a Controller, using a HandlerMapping. When a Controller has been found to handle the request, the handleRequest method of the located Controller will be invoked; the located Controller is then responsible for handling the actual request and - if applicable - returning an appropriate ModelAndView.
Thats it.

Actually, injection with xml and annotation is same behind the scene. Xml is old fashion while annotations are newer.
Basically, there are 2 types of injection types.
byName
Autowiring by property name. Spring container looks at the properties
of the beans on which autowire attribute is set to byName in the XML
configuration file. It then tries to match and wire its properties
with the beans defined by the same names in the configuration file.
You can give explicit names to beans both with xml and annotation.
#Service("BeanName")
#Component("BeanName")
#Controller("BeanName")
<bean name="BeanName" class="someclass"></bean>
and inject beans by using #Qualifier annotation.
#Autowired
#Qualifier("BeanName")
and with xml
<bean id="MyBean2" class="MyBean2 class">
<property name="Property of MyBean2 which refers to injecting bean" ref="BeanName" />
</bean>
byType
Autowiring by property datatype. Spring container looks at the
properties of the beans on which autowire attribute is set to byType
in the XML configuration file. It then tries to match and wire a
property if its type matches with exactly one of the beans name in
configuration file. If more than one such beans exists, a fatal
exception is thrown.
Default auto wiring mode is byType, so spring will look for matching type in auto wiring. However, older versions of Spring has default behavior none on injection. If you want to inject byType using xml, you should tell spring contaioner explicitly.
For example MyBean2 has a reference to MyBean, by setting autowired attribute to byType it handles injection automatically.
<bean id="MyBean" class="MyBean class">
<property name="Property of MyBean2 which refers to injecting bean" ref="BeanName" />
</bean>
<bean id="MyBean2" class="MyBean2 class"
autowire="byType">
</bean>
It also depends on where the injection take place in your code. There are 2 types, setter getter injection and constructor injection.
Note : There is no difference in #Controller since they are already in spring context.
See also
Spring Beans Auto wiring

I ran into such problem. I was getting "Ambiguous mapping found". (I use xml configuration as well and i am injecting a bean into my controller)
Then looking at my console i realized that my controller was being instantiated twice.
In more detailed look i noticed that my annotation
#Controller(value = "aController")
(Note value = "aController")
was different from my xml configuration where i was instatiating the same controller with different bean id
<bean id="aControleRRRRR" class="package.ControllerClassName"
p:property-ref="beanToInject" />
(Note id="aControleRRRRR")
So in conclusion your #Controller name (value = "aController") needs to be exactly the same as the name you give in the XML configuration (id="aControleRRRRR"), so that Spring can manage to distinct that they refer to the same bean (instance)
Hope this helps

Can spring container inject collaborators using custom methods?

Normally dependencies are injected via setters by the following configuration (http://static.springsource.org/sprin...beans-beanname) :
<bean id="exampleBean" class="examples.ExampleBean">
<!-- setter injection using the nested <ref/> element -->
<property name="beanOne"><ref bean="anotherExampleBean"/></property>
<!-- setter injection using the neater 'ref' attribute -->
<property name="beanTwo" ref="yetAnotherBean"/>
<property name="integerProperty" value="1"/>
</bean>
<bean id="anotherExampleBean" class="examples.AnotherBean"/>
<bean id="yetAnotherBean" class="examples.YetAnotherBean"/>
Lets say the class examples.ExampleBean has a collection listeners objects, and the method addListener(SomeListenerInterface) is the only possible way add listeners. Can I inject listeners declaratively in xml like its done with property setters?

You could probably conjure up some baroque mechanism for doing this all in XML, but the cleanest way to do this is to use a FactoryBean. You write a class which implement FactoryBean, and which is responsible for constructing and configuring your target object (see Spring docs). Your FactoryBean would have the required getters/setters/autowiring, and injects them into the target object.
This is often the cleanest way to handle non-javabeans in Spring, particularly if you cannot modify the target class.

Here goes property Element definition
Property elements correspond to JavaBean setter methods exposed by the bean classes.
To get your goal, you can use #Autowired annotation. It works even when using an arbitrary name
#Autowired
public void inject(SomeListenerInterface someListenerInterface) {
this.someListenerInterface = someListenerInterface;
}

Are there Compound property values in Spring

I read about Compound property names in the "The Spring Framework (2.5) - Reference Documentation - chapter 3.3.2.7"
Can i use the same concept to set values of properties? Can i use a compound string as a value expression?
<bean id="service1" class="a.b.c.Service1Impl" scope="prototype">
<property name="service2" ref="service2"/>
<property name="service2.user" value="this-service1-instance.user"/>
</bean>
<bean id="service2" class="a.b.c.Service2Impl" scope="prototype">
...
</bean>
User is a property of a.b.c.Service1Impl which is not in control of Spring. I want to forward this property to a.b.c.Service2Impl.

Rather than use a plain old factory bean, rather use a factory method to create the bean of the property and then inject that result...
iow
in your case, it would look something like this...
<!-- the bean to be created via the factory bean -->
<bean id="exampleBean"
factory-bean="serviceLocator"
factory-method="createInstance"/>
So the bean of id is created by calling createInstance on bean serviceLocator.
Now spring does not support nested properties out of the box, though you could look at creating a custom editors which might provide that support - possible but tricky. Possibly not worth the effort.
One mechanism you could look at using is nesting using the factory-bean factory-method technique...
Something like:
<bean id="c" class="C" />
<bean id="b" factory-bean="c" factory-method="getB"/>
<bean id="a" factory-bean="b" factory-method="getA"/>
This will effectively expose: a.b.c where C has a method getB and A has a method getB

I had to do something similar, and I'm afraid it's not possible. I had to write a [FactoryBean][1] to expose the property.
It would look something like this:
public class UserFactory implements BeanFactory {
private Service2 service2;
// ... setter and getter for service2
public Object getObject() {
return getService2().getUser();
}
public Class getObjectType() {
return User.class;
}
public boolean isSingleton() {
// Since it's a prototype in your case
return false;
}
}
Come to think of it, in your case, you'd probably define the factory itself as a prototype, in which case your isSingleton() may return true, you'll need to play around with this a little bit.

Spring's XML wiring syntax supports lists, maps and properties objects, and you can create other 'data' objects via property editors.
Edit: (Oh I see what you are asking.) I think that the answer is no. I don't recall having seen any mention of calling getters on a bean or non-bean object in the Spring documentation, let alone a syntax for doing this in the wiring file. It tends to go against the grain. Spring wiring is declarative, and calling a getter would lead to patterns that are bordering on procedural.