[Translate]11-spring bean-defined inheritance

The bean definition in spring contains a lot of information, such as constructor parameters, property-specified dependencies, initialization methods, factory classes, and factory methods.

If each bean in the spring container repeatedly declares these properties, it is very annoying and very inefficient and error-prone. Fortunately, the spring bean definition can be

to inherit.

A child's bean definition can inherit all the attributes from a parent bean definition, and the child Bean's definition can override its inherited

The property defined by the parent bean.

You can use the Parent property in the definition of a bean to specify the bean definition that it needs to inherit. Let's look at an example:

1. Create a new package Com.tutorialspoint.bean_inherit and create a new HelloWorld and Helloindia class in the package. The contents are as follows:

Helloworld.java as follows:

 PackageCom.tutorialspoint.bean_inherit; Public classHelloWorld {PrivateString Message1; PrivateString Message2;  Public voidsetMessage1 (String message) { This. Message1 =message; }     Public voidsetMessage2 (String message) { This. Message2 =message; }     Public voidGetMessage1 () {System.out.println ("World Message1:" +message1); }     Public voidGetMessage2 () {System.out.println ("World Message2:" +message2); }}

Helloindia.java as follows:

 PackageCom.tutorialspoint.bean_inherit; Public classHelloindia {PrivateString Message1; PrivateString Message2; PrivateString Message3;  Public voidsetMessage1 (String message) { This. Message1 =message; }     Public voidsetMessage2 (String message) { This. Message2 =message; }     Public voidsetMessage3 (String message) { This. Message3 =message; }     Public voidGetMessage1 () {System.out.println ("India Message1:" +message1); }     Public voidGetMessage2 () {System.out.println ("India Message2:" +message2); }     Public voidGetMessage3 () {System.out.println ("India Message3:" +message3); }}

2. In the SRC directory, create a new bean_inherits.xml configuration file with the following content:

<?XML version= "1.0" encoding= "UTF-8"?><Beansxmlns= "Http://www.springframework.org/schema/beans"Xmlns:xsi= "Http://www.w3.org/2001/XMLSchema-instance"xsi:schemalocation= "Http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/ Spring-beans-3.0.xsd ">   <BeanID= "HelloWorld"class= "Com.tutorialspoint.bean_inherit." HelloWorld ">      < Propertyname= "Message1"value= "Hello world!"/>      < Propertyname= "Message2"value= "Hello Second world!"/>   </Bean>   <!--to specify the definition of the bean that needs to be inherited through the parent property -   <!--overrides the parent's Message1 property -   <!--inherits the Message2 property of the parent -   <!--newly added Helloindia's Message3 property -   <BeanID= "Helloindia"class= "Com.tutorialspoint.bean_inherit." Helloindia "Parent= "HelloWorld">      < Propertyname= "Message1"value= "Hello india!"/>      < Propertyname= "Message3"value= "Namaste india!"/>   </Bean></Beans>

3. Create a new Mainapp.java class in package Com.tutorialspoint.bean_inherit with the following contents:

 PackageCom.tutorialspoint.bean_inherit;ImportOrg.springframework.context.support.AbstractApplicationContext;ImportOrg.springframework.context.support.ClassPathXmlApplicationContext; Public classMainapp { Public Static voidMain (string[] args) {Abstractapplicationcontext context=NewClasspathxmlapplicationcontext ("Bean_inherits.xml"); HelloWorld Obja= (HelloWorld) context.getbean ("HelloWorld");        Obja.getmessage1 ();        Obja.getmessage2 (); Helloindia OBJB= (Helloindia) context.getbean ("Helloindia");        Objb.getmessage1 ();        Objb.getmessage2 ();                Objb.getmessage3 ();    Context.registershutdownhook (); }}

4. Run the code and check the results:

Bean-defined templates

If we only need to use the Helloindia class, it is cumbersome to define the HelloWorld class simply for inheritance. Fortunately spring supports bean-defined templates

The template for the bean definition is to add the <bean/> element to the abstract= "true" property without having to specify the class attribute. Other beans directly from the bean template

Underwriting We have modified the configuration file Bean_inherits.xml of the above code to read as follows:

<?XML version= "1.0" encoding= "UTF-8"?><Beansxmlns= "Http://www.springframework.org/schema/beans"Xmlns:xsi= "Http://www.w3.org/2001/XMLSchema-instance"xsi:schemalocation= "Http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/ Spring-beans-3.0.xsd ">    <BeanID= "Beanteamplate"Abstract= "true">      < Propertyname= "Message1"value= "Hello world!"/>      < Propertyname= "Message2"value= "Hello Second world!"/>      < Propertyname= "Message3"value= "Namaste india!"/>    </Bean>   <!--to specify the template for the bean definition that needs to be inherited through the parent property -   <!--overrides the parent's Message1 property -   <!--inherits the Message2 property of the parent -   <!--inherits the Message3 property of the parent -   <BeanID= "Helloindia"class= "Com.tutorialspoint.bean_inherit." Helloindia "Parent= "Beanteamplate">      < Propertyname= "Message1"value= "Hello india!"/>   </Bean></Beans>

and change the Mainapp.java to the following content:

 PackageCom.tutorialspoint.bean_inherit;ImportOrg.springframework.context.support.AbstractApplicationContext;ImportOrg.springframework.context.support.ClassPathXmlApplicationContext; Public classMainapp { Public Static voidMain (string[] args) {Abstractapplicationcontext context=NewClasspathxmlapplicationcontext ("Bean_inherits.xml"); Helloindia OBJB= (Helloindia) context.getbean ("Helloindia");        Objb.getmessage1 ();        Objb.getmessage2 ();                Objb.getmessage3 ();    Context.registershutdownhook (); }}

Continue running the Mainapp.java class and check the results to see that it is working correctly:

[Translate]11-spring bean-defined inheritance