SpringMVC servlet mapping

Question

I've written a really simple Spring MVC app. I apologise I'm rather new to Spring MVC so bear with me.

The web.xml is as follows

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 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_2_5.xsd">

    <!-- The definition of the Root Spring Container shared by all Servlets and Filters -->
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/spring/root-context.xml</param-value>
    </context-param>

    <!-- Creates the Spring Container shared by all Servlets and Filters -->
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

    <!-- Processes application requests -->
    <servlet>
        <servlet-name>appServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/spring/appServlet/servlet-context.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>appServlet</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

</web-app>

My first question is, I have a jsp page for login with the following code...

<form action="/login" method="post" >
Username : <input name="username" type="text" />
Password : <input name="password" type="password" />
<input type="submit" />
</form>

This gives a 404 but in my Controller, I've mapped the controller to /login with the code below...

@Controller
public class LoginController {

    private static final Logger logger = LoggerFactory.getLogger(LoginController.class);

    /**
     * Simply selects the home view to render by returning its name.
     */
    @RequestMapping(value = "/login", method = RequestMethod.POST)
    public String home(Locale locale, Model model, String username, String password) {

        if(username.equalsIgnoreCase("david"))
        {
            logger.info("Welcome home! the client locale is "+ locale.toString());

            Date date = new Date();
            DateFormat dateFormat = DateFormat.getDateTimeInstance(DateFormat.LONG, DateFormat.LONG, locale);

            String formattedDate = dateFormat.format(date);

            model.addAttribute("serverTime", formattedDate );

            return "home";
        }
        else
        {
            return "void";
        }

    }

}

My understanding is the @requestmapping should do the servlet mapping rather than in the web.xml, is this correct? The value of /WEB-INF/spring/appServlet/servlet-context.xml is shown below also if needed.

<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns="http://www.springframework.org/schema/mvc"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:beans="http://www.springframework.org/schema/beans"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-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">

    <!-- DispatcherServlet Context: defines this servlet's request-processing infrastructure -->

    <!-- Enables the Spring MVC @Controller programming model -->
    <annotation-driven />

    <!-- Handles HTTP GET requests for /resources/** by efficiently serving up static resources in the ${webappRoot}/resources directory -->
    <resources mapping="/resources/**" location="/resources/" />

    <!-- Resolves views selected for rendering by @Controllers to .jsp resources in the /WEB-INF/views directory -->
    <beans:bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <beans:property name="prefix" value="/WEB-INF/views/" />
        <beans:property name="suffix" value=".jsp" />
    </beans:bean>

    <context:component-scan base-package="org.david.myapp" />



</beans:beans>

So my first question is : is the servlet mapping done in the web.xml or at the @requestmapping in the controller class?

Second question : what's the best way to architect this to have more pages, should I keep appending to the webxml? Should I create a controller for every url? Should I create a servlet-context for every url?

Thanks for reading :)

I didnt check the whole thing you gave, but on a first view your request method on the controller is GET, where your form uses a POST method. Seems to be a mistake... — Omnaest
– Omnaest, Commented Jan 7, 2012 at 11:01
ah, thank you changed but still same issue, edited code above to reflect this. — David
– David, Commented Jan 7, 2012 at 11:33

matsev · Accepted Answer · 2012-01-08 09:41:43Z

8

You have defined <url-pattern> to be /, which means that your appServlet will only receive requests to the root url. By changing it to /* the appServlet will get all incoming requests. This will work, but you can also consider to create a specific loginServlet which could be mapped to url /login/*.

You can have multiple servlets defined in a single web.xml. Which request will hit each servlet is specified by adding more <servlet-mapping> tags.
A servlet may have many controllers. Typically, one controller serves a specific part of your domain, e.g. PersonController, AddressController, etc.
Each controller usually handles several urls that are logically grouped together, e.g. /persons/{id}, /persons/search, /persons/add, etc.

edited Jan 8, 2012 at 9:41

answered Jan 7, 2012 at 11:59

matsev

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6 Comments

David Over a year ago

Ah ok, so if the servlet-mapping is done in the web.xml, what's the purpose of the @RequestMapping(value = "/login", method = RequestMethod.POST) in the controller class? Thank you :)

matsev Over a year ago

You can use @RequestMapping both on class level and method level to implement a fine grained control of how different requests will be handled. The different handling can be based on the url (c.f. item 3 above), HTTP method, and / or different request parameters. More information about request mapping can be found in the Spring manual

David Over a year ago

ok, sorry I've probably confused myself, but if I have /login in the web.xml mapped to a servlet-context and then /login in the @RequestMapping, does that then mean to reach this controller I have to go to /login/login ? Thanks for your help.

David Over a year ago

I understand this can be done at both class and method level but I still don't quite understand the purpose if I have to copy the same path servlet-mapping in the web.xml

matsev Over a year ago

It is not the same path. The <url-pattern> in the web.xml constitutes the logical mapping of different servlets, whereas @RequestMapping handles incoming requests for each controller respectively. If for example http://localhost:8080/example/login have a specific servlet mapping, say /example/*, then the request url will be /login. Alternatively, if the servlet mapping is /*, then the request url will be /example/login. If you are implementing only one servlet then you should use the "catch all" /* servlet mapping so that the servlet is hit by all incoming requests.

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