Difference between applicationContext.xml and spring-servlet.xml in Spring Framework
Scenario 1
In client application (application is not web application, e.g may be swing app)
private static ApplicationContext context = new ClassPathXmlApplicationContext("test-client.xml");
context.getBean(name);
No need of web.xml. ApplicationContext as container for getting bean service. No need for web server container. In test-client.xml there can be Simple bean with no remoting, bean with remoting.
Conclusion: In Scenario 1 applicationContext and DispatcherServlet are not related.
Scenario 2
In a server application (application deployed in server e.g Tomcat). Accessed service via remoting from client program (e.g swing app)
Define listener in web.xml
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
At server startup ContextLoaderListener instantiates beans defined in applicationcontext.xml.
Assuming you have defined the following in applicationcontext.xml:
<import resource="test1.xml" />
<import resource="test2.xml" />
<import resource="test3.xml" />
<import resource="test4.xml" />
The beans are instantiated from all four configuration files test1.xml, test2.xml, test3.xml, test4.xml.
Conclusion: In Scenario 2 applicationContext and DispatcherServlet are not related.
Scenario 3
In a web application with spring MVC.
In web.xml define:
<servlet>
<servlet-name>springweb</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>springweb</servlet-name>
<url-pattern>*.action</url-pattern>
</servlet-mapping>
When tomcat starts, beans defined in springweb-servlet.xml are instantiated. DispatcherServlet extends FrameworkServlet. In FrameworkServlet bean instantiation takes place for springweb . In our case springweb is FrameworkServlet.
Conclusion: In Scenario 3 applicationContext and DispatcherServlet are not related.
Scenario 4
In web application with spring MVC. springweb-servlet.xml for servlet and applicationcontext.xml for accessing the business service within the server program or for accessing DB service in another server program.
In web.xml the following are defined:
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<servlet>
<servlet-name>springweb</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>springweb</servlet-name>
<url-pattern>*.action</url-pattern>
</servlet-mapping>
At server startup, ContextLoaderListener instantiates beans defined in applicationcontext.xml; assuming you have declared herein:
<import resource="test1.xml" />
<import resource="test2.xml" />
<import resource="test3.xml" />
<import resource="test4.xml" />
The beans are all instantiated from all four test1.xml, test2.xml, test3.xml, test4.xml. After the completion of bean instantiation defined in applicationcontext.xml then beans defined in springweb-servlet.xml are instantiated.
So instantiation order is root is application context, then FrameworkServlet.
Now it makes clear why they are important in which scenario.
<ref:http://stackoverflow.com/a/15941066>
<context:component-scan base-package=“com.test" />
HandlerMapping，是SpringMVC中用来处理Request请求URL到具体Controller的，其自身也分成很多种类；
HandlerAdapter，是SpringMVC中用来处理具体请求映射到具体方法的，其自身也分很多种类；
@RequestMapping这个注解的主要目的就是对具体的Controller和方法进行注册，以方便HandlerMapping用来处理请求的映射。但是@RequestMapping需要结合<mvc:annotation-driven />使用才能生效。
protected void initHandlerMethods() {
if (logger.isDebugEnabled()) {
logger.debug("Looking for request mappings in application context: " + getApplicationContext());
}
String[] beanNames = (this.detectHandlerMethodsInAncestorContexts ?
BeanFactoryUtils.beanNamesForTypeIncludingAncestors(getApplicationContext(), Object.class) :
getApplicationContext().getBeanNamesForType(Object.class));
for (String beanName : beanNames) {
if (isHandler(getApplicationContext().getType(beanName))){
detectHandlerMethods(beanName);
}
}
handlerMethodsInitialized(getHandlerMethods());
}
protected boolean isHandler(Class<?> beanType) {
return AnnotationUtils.findAnnotation(beanType, Controller.class) != null;
}
<bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping"> <property name="detectHandlerMethodsInAncestorContexts"> <value>true</value> </property> </bean>
Spring容器配置，排除所有@controller的Bean
<context:component-scan base-package="com.fsnip.open"> <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Controller"/> </context:component-scan>
SpringMVC容器配置，让其只包括@controller的Bean
<context:component-scan base-package="com.fsnip.open" use-default-filters="false"> <context:include-filter type="annotation" expression="org.springframework.stereotype.Controller" /> </context:component-scan>