Introducing Spring Framework

Chapter 4 ■ Using Beans Scopes
The result is one SearchEngineService instance and one DocumentDAO instance (your concrete class,
DocumentRespository). But why? Remember that by default the Spring Framework only creates a Singleton
instance of your bean, so even if you call this bean (with the getBean method) several times, you are going to get
the same instance.
Now, let’s modify the XML and how the Spring container uses the bean scopes. See Listing 4-3 for the XML
configuration.
Listing 4-3. mydocuments-context.xml
In Listing 4-3, you added the scope prototype attribute to the beans engine and documentDAO. The Spring
container will create a new instance of these classes once the getBean method from the application context is called.
If you run the test again, you will see the following output:
$ gradle –Dtest.simple=MyDocumentTest test
DEBUG [main] ServiceSearchEngine created: com.apress.isf.spring.service.ServiceSearchEngine@2ac1d29e
DEBUG [main] Document DAO set: com.apress.isf.spring.data.DocumentRepository@702557dd
DEBUG [main] ServiceSearchEngine created: com.apress.isf.spring.service.ServiceSearchEngine@23aba7b0
DEBUG [main] Document DAO set: com.apress.isf.spring.data.DocumentRepository@5a8e261b
As you can see, now you have different instances because you call the method getBean twice for the engine and
every time you get a new instance; the same happens for the documentDAO setter.
Table 4-1 shows how the Bean Scopes are handled by the Spring container. These scopes can be defined as an
attribute in the bean tag (XML context) or as a @Scope annotation if you are using annotation or Java configuration classes.
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