Wiring a prototype in blueprint

问题:

Like Spring, blueprint supports the prototype scope. But unlike Spring I can't see any documentation about how to use it.

In Spring you can ask the context to give you a new bean, what's the equivalent in the Blueprint world?

回答1:

BlueprintContainer.getComponentInstance() does exactly what you are looking for.

osgi documentation:

A Blueprint Container represents the managed state of a Blueprint bundle. A Blueprint Container provides access to all managed components. These are the beans, services, and service references. A Blueprint Container can be obtained by injecting the predefined "blueprintContainer" component id.

Example

blueprint.xml:

<!-- blueprintContainer is predefined component here -->
<bean id="myService" class="myPackage.MyService">
   <property name="container" ref="blueprintContainer"/>
</bean>
<!-- prototype which can be created from myService -->
<bean id="myPrototype" class="myPackage.MyPrototype" scope="prototype"/>

MyService.java:

// ...
// create new instance
MyPrototype myPrototype = 
     (MyPrototype) container.getComponentInstance("myPrototype");

pom.xml:

<!-- BlueprintContainer from Apache Aries-->
<dependency>
  <groupId>org.apache.aries.blueprint</groupId>
  <artifactId>org.apache.aries.blueprint.core</artifactId>
  <version>1.3.0</version>
</dependency>

回答2:

If a bean is of scope prototype then a new instance of the bean is created each time the bean is injected somewhere. Therefore each client that gets a bean of scope prototype injected gets a new instance of the bean.