Spring mvc with jdbc template

Question

I want to implements simple login with spring mvc and jdbc template. but I am getting null pointer exception. I have included spring-core.jar,spring-jdbc.jar,spring-txn.jar,spring-web.jar..

    ****Complete stack trace:****

      May 17, 2015 6:54:54 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [login] in context with path [/MVCWithJDBC] threw exception [Request processing failed; nested exception is java.lang.NullPointerException] with root cause
java.lang.NullPointerException
    at com.mvc.dao.LoginDAOImpl.getLoginDetails(LoginDAOImpl.java:25)
    at com.mvc.controller.LoginController.handleRequest(LoginController.java:30)
    at org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter.handle(SimpleControllerHandlerAdapter.java:48)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:771)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:716)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:647)
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:563)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:646)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:504)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:421)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1074)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:611)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)

    **Web.xml:**

        <?xml version="1.0" encoding="UTF-8"?>
        <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
          <display-name>MVCMultpleActions</display-name>
          <welcome-file-list>
           <welcome-file>login.jsp</welcome-file>
          </welcome-file-list>
           <servlet>
            <servlet-name>login</servlet-name>
            <servlet-class>
                 org.springframework.web.servlet.DispatcherServlet
              </servlet-class>
            <load-on-startup>1</load-on-startup>
          </servlet>
          <servlet-mapping>
            <servlet-name>login</servlet-name>
            <url-pattern>*.ak</url-pattern>
          </servlet-mapping>  
        </web-app>

    **login-servlet.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:p="http://www.springframework.org/schema/p"  
            xsi:schemaLocation="http://www.springframework.org/schema/beans  
                       http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">  
         <bean name="/login.ak" class="com.mvc.controller.LoginController"> </bean>
         <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
              <property name="prefix" value="/WEB-INF/jsp/" />
              <property name="suffix" value=".jsp" />
         </bean>
        <bean id="ds" class="org.springframework.jdbc.datasource.DriverManagerDataSource">  
        <property name="driverClassName" value="oracle.jdbc.driver.OracleDriver" />  
        <property name="url" value="jdbc:oracle:thin:@localhost:1521:xe" />  
        <property name="username" value="system" />  
        <property name="password" value="mysql" />  
        </bean>     


        <bean id="logindao" class="com.mvc.dao.LoginDAOImpl">  
        <property name="dataSource" ref="ds"></property> 
        </bean>
        </beans>

        **DAO Classes:**
        package com.mvc.dao;

    import javax.sql.DataSource;

    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.jdbc.core.JdbcTemplate;
    import org.springframework.jdbc.core.support.JdbcDaoSupport;
    import org.springframework.jdbc.datasource.DriverManagerDataSource;

    import com.mvc.mapper.*;
    import com.mvc.dto.LoginDTO;

    public class LoginDAOImpl extends JdbcDaoSupport implements LoginDAO {

        @Override
        public LoginDTO getLoginDetails(String userName) {
            // TODO Auto-generated method stub
            System.out.println("userName:"+userName);
            String query="select password from Login where userName=?";
            System.out.println("query"+query);
            return getJdbcTemplate.queryForObject(query,new Object[]{userName},new LoginMapper());

            }

    }

    **Controller:**

        package com.mvc.controller;

        import javax.servlet.http.HttpServletRequest;
        import javax.servlet.http.HttpServletResponse;

        import org.springframework.context.ApplicationContext;
        import org.springframework.context.support.ClassPathXmlApplicationContext;
        import org.springframework.web.servlet.ModelAndView;
        import org.springframework.web.servlet.mvc.Controller;

        import com.mvc.dao.LoginDAOImpl;
        import com.mvc.dto.LoginDTO;

        public class LoginController implements Controller{

            @Override
            public ModelAndView handleRequest(HttpServletRequest req,
                    HttpServletResponse res) throws Exception {
                // TODO Auto-generated method stub
                String name=req.getParameter("userName");
                String password=req.getParameter("password");
                LoginDAOImpl login=new LoginDAOImpl();
                LoginDTO loginDto=new LoginDTO();
                loginDto.setUserName(name);
                loginDto.setPassword(password);
                System.out.println("pw:"+password);
                String pw=login.getLoginDetails("admin").getPassword();
                System.out.println("dao pw:"+pw);
                if(password.equalsIgnoreCase(pw))
                {
                     String message = "HELLO "+name;  
                      return new ModelAndView("hellopage", "message", message);  
                  }  
                  else{  
                            return new ModelAndView("errorpage", "message","Sorry, username or password error");  
                        }  

            }


        }

Answer 1

You can simply extend JdbcDaoSupport

public class LoginDAOImpl extends JdbcDaoSupport implements LoginDAO {
//codes
}

while jdbcTemplate setter method can be removed from this implementation class.

And you can also see this tutorial for the reference of my answer.