In Spring, the inheritance is supported in bean configuration for a bean to share common values, properties or configurations.
A child bean or inherited bean can inherit its parent bean configurations, properties and some attributes. In additional, the child beans are allow to override the inherited value.
例子如下：
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public
class
Customer {
private
int
type;
private
String action;
private
String Country;
//...
}
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
<
bean
id="BaseCustomerMalaysia" class="com.mkyong.common.Customer">
<
property
name="country" value="Malaysia" />
</
bean
>
<
bean
id="CustomerBean" parent="BaseCustomerMalaysia">
<
property
name="action" value="buy" />
<
property
name="type" value="1" />
</
bean
>
</
beans
>
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public class App
{
public static void main( String[] args )
{
ApplicationContext context =
new ClassPathXmlApplicationContext("SpringBeans.xml");
Customer cust = (Customer)context.getBean("CustomerBean");
System.out.println(cust);
}
}
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运行结果为：Customer [type=1, action=buy, Country=Malaysia]
In above example, the ‘BaseCustomerMalaysia’ is still able to instantiate, for example,
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Customer cust = (Customer)context.getBean(
"BaseCustomerMalaysia"
);
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类似于java的抽象类，我们可以有：(注意abstract="true")
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
<
bean
id="BaseCustomerMalaysia" class="com.mkyong.common.Customer" abstract="true">
<
property
name="country" value="Malaysia" />
</
bean
>
<
bean
id="CustomerBean" parent="BaseCustomerMalaysia">
<
property
name="action" value="buy" />
<
property
name="type" value="1" />
</
bean
>
</
beans
>
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现在当你运行：
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Customer cust = (Customer)context.getBean(
"BaseCustomerMalaysia"
);
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将会出现：
org.springframework.beans.factory.BeanIsAbstractException: Error creating bean with name 'BaseCustomerMalaysia': Bean definition is abstract
Pure Inheritance Template
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
<
bean
id="BaseCustomerMalaysia" abstract="true">
<
property
name="country" value="Malaysia" />
</
bean
>
<
bean
id="CustomerBean" parent="BaseCustomerMalaysia"
class="com.mkyong.common.Customer">
<
property
name="action" value="buy" />
<
property
name="type" value="1" />
</
bean
>
</
beans
>
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也可以重写值：
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
<
bean
id="BaseCustomerMalaysia" class="com.mkyong.common.Customer" abstract="true">
<
property
name="country" value="Malaysia" />
</
bean
>
<
bean
id="CustomerBean" parent="BaseCustomerMalaysia">
<
property
name="country" value="Japan" />
<
property
name="action" value="buy" />
<
property
name="type" value="1" />
</
bean
>
</
beans
>
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