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I'm receiving the an error when trying to autowire a class that extends JdbcDaoSupport. I have my DAO classes and Controller classes separated into 2 different spring contexts. DAO classes are in the root context and the Controller classes are in the servlet context. I've set up the component-scanning so that there is no overlap in beans between the 2 contexts (is that the correct pattern?). All these factors combined with the fact that my DAOs extend JdbcDaoSupport seems to be causing the issue, and I don't understand why. I'm just learning spring so I don't fully understand all the concepts yet.

EDIT: This behavior seems to be caused by the fact that JdbcDaoSupport/DaoSupport implements the InitializingBean interface. Still confused though.

Here is the error I am receiving:

    Error creating bean with name 'homeController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: org.test.dao.CustomerDAO2 org.test.servlet.HomeController.customerDAO; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [org.test.dao.CustomerDAO2] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

Here are my files:

HomeController.java

package org.test.servlet;

import java.util.Locale;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

import org.test.dao.*;

@Controller
public class HomeController
{
    @Autowired
    CustomerDAO2 customerDAO;

    @RequestMapping(value = "/", method = RequestMethod.GET)
    public String home(Locale locale, Model model)
    {
        model.addAttribute("customer", customerDAO.getCustomer());
        return "home";
    }
}

CustomerDAO2.java

package org.test.dao;

import java.sql.ResultSet;
import java.sql.SQLException;
import javax.sql.DataSource;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.*;
import org.springframework.jdbc.core.support.JdbcDaoSupport;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.*;
import org.test.dto.Customer;

@Repository
public class CustomerDAO2 extends JdbcDaoSupport
{
    public CustomerDAO2()
    {
    }

    @Autowired
    public CustomerDAO2(DataSource datasource)
    {
        this.setDataSource(datasource);
    }

    @Transactional
    public Customer getCustomer()
    {
        JdbcTemplate jdbcTemplate = new JdbcTemplate(getDataSource());
        Customer customer = jdbcTemplate.queryForObject("select * from customer", new CustomerMapper());
        return customer;
    }

    public static class CustomerMapper implements RowMapper<Customer>
    {
        public Customer mapRow(ResultSet rs, int rowNum) throws SQLException
        {
            Customer customer = new Customer();
            customer.setCustomerId(rs.getInt("customerId"));
            customer.setCustomerNumber(rs.getString("customerNumber"));
            return customer;
        }
    }
}

application-context.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"
     xmlns:aop="http://www.springframework.org/schema/aop"
     xmlns:tx="http://www.springframework.org/schema/tx"
     xmlns:context="http://www.springframework.org/schema/context"
     xsi:schemaLocation="
     http://www.springframework.org/schema/beans 
     http://www.springframework.org/schema/beans/spring-beans-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/aop 
     http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
     http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd">

  <!-- Scans within the base package of the application for @Components to configure as beans -->
  <!-- @Controller, @Service, @Configuration, etc. -->
  <context:component-scan base-package="org.test">
    <context:exclude-filter expression="org.springframework.stereotype.Controller" type="annotation"/>
  </context:component-scan>

  <!-- Enables the configuration of transactional behavior based on annotations -->
  <tx:annotation-driven transaction-manager="transactionManager"/>

  <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    <property name="driverClassName" value="com.mysql.jdbc.Driver" />
    <property name="url" value="jdbc:mysql://localhost/crm?user=root&amp;password=password" />
  </bean>

  <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
    <property name="dataSource" ref="dataSource"/>
  </bean>

</beans>

servlet-context.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"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    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">

    <!-- Scans within the base package of the application for @Components to configure as beans -->
    <!-- @Controller, @Service, @Configuration, etc. -->
    <context:component-scan base-package="org.test.servlet"/>

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

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

</beans>
craigrs84
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1 Answers1

1

I found my answer in this post:

Spring expected at least 1 bean which qualifies as autowire candidate for this dependency


Basically, I need to create an interface for my DAO classes. Something like this:

public interface ICustomerDAO {
    Customer getCustomer();
}

Note: it would probably be better to make a more generic CRUD interface.

Then you use the interface type for dependency injection instead of using the class type:

@Autowired
ICustomerDAO customerDAO;

The reason this is necessary is because Spring creates underlying proxy classes:

http://insufficientinformation.blogspot.com/2007/12/spring-dynamic-proxies-vs-cglib-proxies.html

http://docs.spring.io/spring/docs/2.5.x/reference/aop.html#aop-proxying

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craigrs84
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