How Spring is used in WEB apps

1. How does Spring work in WEB apps?

1). Additional jar packages are required:

Spring-web-4.0.0.release.jar
Spring-webmvc-4.0.0.release.jar

2). Spring configuration file, no difference

3). How do I create an IOC container?

①. Non-WEB apps are created directly in the Main method
②. The IOC container should be created when the WEB application is loaded by the server:

Create an IOC container in the servletcontextlistener#contextinitialized (Servletcontextevent sce) method.

③. How do I access the IOC container in other components of the WEB app?

After you create an IOC container in the servletcontextlistener#contextinitialized (Servletcontextevent sce) method, you can place it in the
A property of the ServletContext (that is, the application domain).

④. In fact, the name and location of the Spring configuration file should also be configurable! It is more appropriate to configure it to the initialization parameters of the current WEB application.

4). Use Spring in a WEB environment

①. jar packages that require additional addition:

Spring-web-4.0.0.release.jar
Spring-webmvc-4.0.0.release.jar

②. Spring configuration file, not unlike a non-WEB environment

③. You need to include the following configuration in the Web. xml file:

<!--Configure the name and location of the Spring configuration file--
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:applicationContext.xml</param-value>
</context-param>

<!--launch the IOC container Servletcontextlistener--
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>

2. How does Spring integrate Struts2?

1). Integration Goals? Enable IOC containers to manage Struts2 's action!

2). How do I integrate?

①. Normal Join STRUTS2

②. Configuring the Struts2 Action in the Spring IOC container
Note: When configuring the Struts2 Action in an IOC container, the scope property needs to be configured with a value of prototype

<bean id= "Personaction"
Class= "Com.atguigu.spring.struts2.actions.PersonAction"
Scope= "Prototype" >
<property name= "Personservice" ref= "Personservice" ></property>
</bean>

③. Configuring the Struts2 configuration file: The class attribute of the action node needs to point to the ID of the bean in the IOC container

<action name= "Person-save" class= "Personaction" >
<result>/success.jsp</result>
</action>

④. Join Struts2-spring-plugin-2.3.15.3.jar

3). Integration principle: By adding Struts2-spring-plugin-2.3.15.3.jar, the Struts2 will be first removed from the IOC container
Gets an instance of the Action.

if (Appcontext.containsbean (Beanname)) {
o = Appcontext.getbean (beanname);
} else {
Class Beanclazz = getclassinstance (beanname);
o = Buildbean (Beanclazz, Extracontext);
}

How Spring is used in WEB apps