Spring配置：2个具有相同类引用的bean

Question

Spring-configuration: I have created 2 beans with reference to same class but different database sessions.

<bean id="abc1" class="abc">
<bean id="abc2" class="abc">

Now is there any way to set bean with id "abc1" as default bean for autowiring and use abc2 for autowiring when mentioned explicitly like this:

@Autowiring
@Qualifier("abc2")
private abc obj;

Solution:

<bean id="abc1" class="abc" primary="true">

makes abc1 default one to be autowired.

for creating an instance of abc2, we can use this:

@Autowired
@Qualifier("abc2")
private abc obj;

Answer 1

The @primary annotation or primary attribute of xml is used exactly for that purpose. Here is the details of the same. It is pretty well documented here.

http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/context/annotation/Primary.html

So if you mention <bean id="abc1" class="abc" primary="true"/> it will get priority over abc2 , and you can use @Qualifier for abc2 wherever you need. Hope this helps.

Answer 2

If you skip the @Qualifier annotation, then Spring will lookup for a bean with the same name as the private member. For example:

@Autowired
private abc abc1; //Spring will search for a bean with id="abc1"

This was you can use abc1 as a default value.

If you don't want to make Spring search for a specific bean, then you can trigger the @Qualifier and then Spring will not care how the member is called, but will assign it's value to refer to the bean that has the same id pointed out in the @Qualifier annotation:

@Autowired
@Qualifier("abc2")
private abc theNameDoesNotMatter;