EL表达式仅在特定的JSP页面上显示

Question

I am making a web shop project, and I'm trying to use EL expressions to list out the available categories of products which are being sold. I'm using:

<div class="list-group">

<a href="#" class="list-group-item">Back</a>

<c:forEach items="${products}" var ="product">
<a href="./${product.id}" class="list-group-item"> ${product.name}</a>
</c:forEach> 
</div>

However, the EL expression is being ignored on the "products" page, and not ignored on the index page. Could this be a MVC error in syntax? I could have missed to send something to the view, perhaps something else...

Here is rest of the relevant code:

spring-database.xml-

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:p="http://www.springframework.org/schema/p"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
       http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
       http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
       http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
       http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd">


    <bean id="propertyConfigurer"
          class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"
          p:location="/WEB-INF/jdbc.properties" />

<bean id="dataSource"
    class="org.springframework.jdbc.datasource.DriverManagerDataSource"
    p:driverClassName="${jdbc.driverClassName}"
    p:url="${jdbc.url}"
    p:username="${jdbc.username}"
    p:password="${jdbc.password}" />

<bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
        <property name="dataSource" ref="dataSource" /> 
        <property name="annotatedClasses">
        <list>
           <value>com.mycompany.web_shop.model.Allproducts</value>     
       </list>
        </property>
        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.dialect">org.hibernate.dialect.HSQLDialect</prop>
                <prop key="hibernate.current_session_context_class">thread</prop>
            </props>
        </property> 
    </bean>





    <!-- ADD PERSISTENCE SUPPORT HERE (jpa, hibernate, etc) -->


</beans>

applicationContext.xml -

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:p="http://www.springframework.org/schema/p"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
       http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
       http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
       http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
       http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd">


<mvc:annotation-driven/>
<context:component-scan base-package="com.mycompany.web_shop.controller"/>
<context:component-scan base-package="com.mycompany.web_shop.model"/>
<mvc:resources mapping="/resources/**" location="/resources/"/>

    <!--bean id="propertyConfigurer"
          class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"
          p:location="/WEB-INF/jdbc.properties" />

<bean id="dataSource"
    class="org.springframework.jdbc.datasource.DriverManagerDataSource"
    p:driverClassName="${jdbc.driverClassName}"
    p:url="${jdbc.url}"
    p:username="${jdbc.username}"
    p:password="${jdbc.password}" /-->

    <!-- ADD PERSISTENCE SUPPORT HERE (jpa, hibernate, etc) -->

</beans>

web.xml

<?xml version="1.0" encoding="UTF-8"?>

<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
     version="3.1">
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>
            /WEB-INF/applicationContext.xml, 
            /WEB-INF/spring-database.xml
        </param-value>
    </context-param>
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
    <servlet>
        <servlet-name>dispatcher</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <load-on-startup>2</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>dispatcher</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

    <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
</web-app>

AllproductsDao -

package com.mycompany.web_shop.model;

import java.util.List;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

//@Transactional(propagation = Propagation.REQUIRED, readOnly = false)
@Component
public class AllproductsDao {

    @Autowired
    SessionFactory sessionFactory;

    public List<Allproducts> find() {
        Session session = sessionFactory.getCurrentSession();
        session.beginTransaction();
        List<Allproducts> result = session.createCriteria(Allproducts.class).list();
        session.getTransaction().commit();
        return result;
    }
}

SiteController -

package com.mycompany.web_shop.controller;


import com.mycompany.web_shop.model.Allproducts;
import com.mycompany.web_shop.model.AllproductsDao;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.ui.ModelMap;

@Controller
public class SiteController {


   @Autowired
    AllproductsDao allproductsDao;


     @RequestMapping("/")
    public String index(ModelMap model) {

       List<Allproducts> products = allproductsDao.find();

       model.addAttribute("products", products);

        return "index";
    }


}

I would be grateful for any kind of tip or help, thank you in advance! :)

EDIT - Adding dispatcher-servlet.xml

<

?xml version='1.0' encoding='UTF-8' ?>
<!-- was: <?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:p="http://www.springframework.org/schema/p"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
       http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
       http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd">



    <bean id="viewResolver"
          class="org.springframework.web.servlet.view.InternalResourceViewResolver"
          p:prefix="/WEB-INF/jsp/"
          p:suffix=".jsp" />

</beans>

Answer 1

If you have only SiteController.java as a Spring controller, then the best way from my point of view is to create new controller ProductsController.java in corresponding package:

package com.mycompany.web_shop.controller;
@Controller
public class ProductsController {

  @Autowired
  AllproductsDao allproductsDao;

  @RequestMapping("/products")
  public String listProducts(ModelMap model) {
    List<Allproducts> products = allproductsDao.find();
    model.addAttribute("products", products);
    return "products";
  }
}

Where @RequestMapping("/products") refers to URL like http://localhost:8080/products and return "products" will forward to products.jsp.

Be aware of duplicate code, because now SiteController do the same work actually (filling model with new attribute).

Don't forget to follow naming conventions: Allproducts should be AllProducts (and I guess simply Product), the same for the DAO.