Spring MVC + JDBC, can't connect?

Question

Java

There is an application on Spring MVC that connects to the database, takes data and pulls it out in html format.
I'm using JDK 8, Tomcat 8. I've tried many different options and haven't found a solution. Initially there was this error.

Servlet.init() for servlet dispatcherServlet threw exception

solved it by putting an SchoolDAOImplannotation over the class @Component
This is not the end of my adventures.
Next error:

1) Controller

package com.springapp.mvc.controller;
import java.io.IOException;
import java.util.List;
 
import com.springapp.mvc.dao.SchoolDAO;
import com.springapp.mvc.model.School;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.servlet.ModelAndView;
 
 
@Controller
public class MainController {
 
    @Autowired
    public SchoolDAO schoolDAO;
 
    @RequestMapping(value="/", method = RequestMethod.GET )
    public  ModelAndView listSchools(ModelAndView model) throws IOException{
        List<School> listSchools = schoolDAO.list();
        model.addObject("listSchools", listSchools);
        model.setViewName("home");
 
        return model;
    }
}

2) DAO implementation

package com.springapp.mvc.dao;
 
import com.springapp.mvc.model.School;
import org.springframework.stereotype.Component;
 
import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
 
@Component
public class SchoolDAOImpl implements SchoolDAO {
 
    private DataSource dataSource;
 
    public void setDataSource(DataSource dataSource) {
        this.dataSource = dataSource;
    }
 
    @Override
    public List<School> list() {
        String query = "select * from test.school";
        List<School> listSchools = new ArrayList<School>();
        Connection con = null;
        PreparedStatement ps = null;
        ResultSet rs = null;
        try{
            con = dataSource.getConnection();
            ps = con.prepareStatement(query);
            rs = ps.executeQuery();
            while(rs.next()){
                School aSchool = new School();
                aSchool.setSchool__id(rs.getInt("school__id"));
                aSchool.setUid(rs.getString("uid"));
                aSchool.setGeom(rs.getString("geom"));
                aSchool.setP8c8d9d76(rs.getString("p8c8d9d76"));
                aSchool.setP1bbc78dc(rs.getInt("p1bbc78dc"));
                listSchools.add(aSchool);
            }
        }catch(SQLException e){
            e.printStackTrace();
        }finally{
            try {
                if (rs != null) {
                    rs.close();
                }
                if (ps != null) {
                    ps.close();
                }
                if (con != null) {
                    con.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        return listSchools;
    }
}

3) Spring configuration

<?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:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans [url]http://www.springframework.org/schema/beans/spring-beans.xsd[/url] [url]http://www.springframework.org/schema/context[/url] http://www.springframework.org/schema/context/spring-context.xsd">
 
    <context:annotation-config />
 
       <context:component-scan base-package="com.springapp.mvc" />
 
       <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
           <property name="prefix" value="/WEB-INF/pages/" />
           <property name="suffix" value=".jsp" />
       </bean>
 
       <bean id="schoolDAO" class="com.springapp.mvc.dao.SchoolDAOImpl">
           <property name="dataSource" ref="dataSource" />
       </bean>
 
       <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="root" />
           <property name="password" value="root" />
       </bean>
</beans>

4) Web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
    <display-name>SpringMVC</display-name>
    <context-param>
        <param-name>contextClass</param-name>
        <param-value>
            org.springframework.web.context.support.AnnotationConfigWebApplicationContext
        </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>
        <init-param>
            <param-name>contextClass</param-name>
            <param-value>
                org.springframework.web.context.support.AnnotationConfigWebApplicationContext
            </param-value>
        </init-param>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>com.springapp.mvc</param-value>
        </init-param>
        <load-on-startup>1</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>

If you look in the logs, these lines

java.lang.NullPointerException
    com.springapp.mvc.dao.SchoolDAOImpl.list(SchoolDAOImpl.java:31)
    com.springapp.mvc.controller.MainController.listSchools(MainController.java:23)

then he highlights these

// тут находится null
con = dataSource.getConnection();
// и тут
 List<School> listSchools = schoolDAO.list();

ZY: I'm sorry that the logs are in the image, I also wanted to add pom.xml, but the toaster did not allow it.

Answer 1

Thanks everyone, problem solved.
I created a new project, added all the libraries through maven dependencies.
Most likely, the problem was that I added files of a different version to the spring jdbc jar project, and there was a different version in maven (and they may be in conflict).