How to use Spring autowire annotation in a web-app

Question

New to Spring, I have rushed into it due to the needs of my project. I was successfully able to use most of the features of Spring when using it as a Java application but am not getting the desired results in a web-application.

I am trying to initialize my datasource in applicationContext.xml:

<context:annotation-config />
<context:component-scan base-package="learn.spring.webapp.dao" />

<bean id="dataSource"
    class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    <property name="driverClassName" value="org.postgresql.Driver" />
    <property name="url" value="jdbc:postgresql://localhost:5432/postgres" />
    <property name="username" value="postgres" />
    <property name="password" value="postgres" />
</bean>

<bean id="template" class="org.springframework.jdbc.core.JdbcTemplate"
    autowire="constructor" />

web.xml:

 <context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>WEB-INF/spring/applicationContext.xml</param-value>
  </context-param>

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

I was successfully able to initialize Spring in my application but fail to autowire jdbctemplate in my dao class.

package learn.spring.webapp.dao;

import learn.spring.webapp.model.Manga;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Component;

@Component
public class MangaDao {
    @Autowired
    private JdbcTemplate jdbcTemplate;

    public void insert(Manga manga){
        String sql = "insert into manga_list values (?,?)";
        jdbcTemplate.update(sql,
                new Object[]{manga.getName(), manga.getAuthor()}); //Null Pointer exception
    }
}

I want to autowire the template bean with JdbcTemplate in my dao package. I get a NullPointerException when I try to use the JdbcTemplate. MangaDao is being called from a servlet. I think I might not be using the autowired annotations correctly. Please advice.

Edit:

The servlet code that calls the DAO is:

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        MangaDao md=new MangaDao();
        Manga manga=new Manga();
        manga.setName("Bleach");
        manga.setAuthor("Kubo Tite");
        md.insert(manga);
    }

And the stackTrace is as follows:

SEVERE: Servlet.service() for servlet TesterServlet threw exception
java.lang.NullPointerException
        at learn.spring.webapp.dao.MangaDao.insert(MangaDao.java:16)
        at learn.spring.webapp.controller.TesterServlet.doGet(TesterServlet.java:33)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
        at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
        at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
        at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
        at java.lang.Thread.run(Thread.java:662)