Spring(4)----Bean Scope----part2

#Tip of the Day: I changed the memory of the virtual machine from 8G to 4G, but the speed is improved a little.

Video Link

Web scopes

Web Context creation

To test the web scopes, we need to create a Web context for our application.

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0"
         xmlns="http://java.sun.com/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">

    <servlet>
        <servlet-name>SpringServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:spring.xml</param-value>
        </init-param>
    </servlet>
    <servlet-mapping>
        <servlet-name>SpringServlet</servlet-name>
        <url-pattern>/*</url-pattern>
    </servlet-mapping>
</web-app>

Three bean classes. I only show RequestController.java here, the other two are similar.

@Controller
public class RequestController {
    @RequestMapping("testRequest")
    @ResponseBody
    public String test(){
        return this.toString();
    }
}

spring.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="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.xsd">
    <bean class="springioc.class008.ApplicationController"/>
    <bean class="springioc.class008.RequestController"/>
    <bean class="springioc.class008.SessionController"/>
</beans>

Run with Tomcat

To run our application, we need to create a tomcat server. Download a tomcat if you don’t have one.

Notice that I changed the Application context to : “/”

Then run this tomcat server, and open browser, go to “http://localhost:8080/testRequest” then, we can get a response.springioc.class008.RequestController@2ce58ae3

Request scope

Every time we send a request, a new bean will be created. If we change the spring.xml file

<bean class="springioc.class008.ApplicationController" scope="request"/>

Then every time we refresh, we will get a new bean.

Session scope

Similarly, in each session, we have a same bean.

Application scope

In the whole application, we only have one single bean.