Wednesday, August 29, 2012

Spring MVC tutorial

Before Starting, I believe you must have basic idea about JAVA, SPRING and Spring MVC.

For Spring MVC : http://waheedtechblog.blogspot.in/2012/08/spring-mvc.html

In this tutorial , I will just tell you what are the basic thing that you need to start MVC.

Step 1 : Create a class 


@Controller
public class HelloWorld {
 
    @RequestMapping("/hello")
    public String helloWorld() {
         return = "Hello World, Spring 3.0!";
    }
}


1 . The class HelloWorld  has the annotation @Controller and @RequestMapping("/hello"). When Spring scans this class, it will recognize this bean as being a Controller bean for processing requests. 2 .The @RequestMapping annotation tells Spring that this Controller should process all requests beginning with /hello in the URL path.

Step 2. Mapping Spring MVC in WEB.xml

The entry point of Spring 3.0 MVC is the DispatcherServlet. DispatcherServlet is a normal servlet class which implements HttpServlet base class. Thus we need to configure it in web.xml.

<!-- ========================== -->
    <!-- Spring MVC: Core -->
    <!-- ========================== -->

    <servlet>
        <servlet-name>spring</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>spring</servlet-name>
        <url-pattern>/rest/*</url-pattern>
    </servlet-mapping>

<!-- This loads the root webapp Spring context -->
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:beans.xml</param-value>
    </context-param>
   
    <welcome-file-list>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>

    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

Note that I have mapped /rest/* url pattern with example DispatcherServlet. Thus any url with /rest/* pattern will call Spring MVC Front controller.

                  The REST call would be http://ip:port/rest/hello

If your controller class has some dependency which you have defined in your spring context file.Then you have to load it in <context-param>.(red line).
Once the DispatcherServlet is initialized, it will looks for a file name [servlet-name]-servlet.xml in WEB-INF folder of web application. I have created the file named spring-servlet.xml


3 . Spring Configuration file

Create a file spring-servlet.xml in WEB-INF folder and copy following content into it.
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:task="http://www.springframework.org/schema/task"
    xmlns:tx="http://www.springframework.org/schema/tx" xmlns:context="http://www.springframework.org/schema/context"
    xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:util="http://www.springframework.org/schema/util"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xsi:schemaLocation="http://www.springframework.org/schema/task
    http://www.springframework.org/schema/task/spring-task-3.0.xsd
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-3.0.xsd
        http://www.springframework.org/schema/tx
        http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd
        http://www.springframework.org/schema/util
        http://www.springframework.org/schema/util/spring-util-2.0.xsd
        http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
        ">

    <!-- ========================== -->
    <!-- Spring MVC: Core -->
    <!-- ========================== -->

    <context:annotation-config />
    <mvc:annotation-driven />
    <mvc:default-servlet-handler />

    <!-- class name of the controller or If you have package use component-scan -->
    <bean class="com.waheed.spring.hibernate.HelloWorld" />

 </beans>

The highlighted red line allow Spring to load the components from class. This will load our HelloWorld class.

Congratulation..!!! You are done here...

Download source code : https://github.com/abdulwaheed18/SpringMVC-Hibernate-Integration