Spring Boot and Dao

Question

I have uploaded a public project on Github:

https://github.com/sotish/SpringMVC11.git

My model class is:

    import javax.persistence.Column;
    import javax.persistence.Entity;
    import javax.persistence.GeneratedValue;
    import javax.persistence.GenerationType;
    import javax.persistence.Table;

    import org.springframework.boot.orm.jpa.EntityScan;
    import org.springframework.data.annotation.Id;

    @EntityScan
    @Entity
    @Table(name = "Student")
    public class Student {

        @Id
        @GeneratedValue(strategy = GenerationType.AUTO)
        private int id;

     @Column(nullable= false, unique=true)
        private String firstName;

     @Column(nullable= false, unique=true)
        private String lastName;

     @Column(nullable= false, unique=true)
        private int age;

     @Column(nullable= false)
        private String email;

     //getter and setters

        public int getId() {
            return id;
        }

        public void setId(int id) {
            this.id = id;
        }

        public String getFirstName() {
            return firstName;
        }

        public void setFirstName(String firstName) {
            this.firstName = firstName;
        }

        public String getLastName() {
            return lastName;
        }

        public void setLastName(String lastName) {
            this.lastName = lastName;
        }

        public Integer getAge() {
            return age;
        }

        public void setAge(int age) {
            this.age = age;
        }

        public String getEmail() {
            return email;
        }

        public void setEmail(String email) {
            this.email = email;
        }

    }

I made a Student interface :-

package com.sat.Dao;

import java.util.List;

public interface Student {

    public void insert(Student student);
    public Boolean update();
    public Student findById(int id);
    public Student findByFirstname(String  firstname);

    List<Student> select(int id, String firstname, String lastname, String       email, int age);
    List<Student> selectAll();

}

studentDao is

import java.util.List;

public class StudentDao implements Student{

@Override
public void insert(Student student) {
    // TODO Auto-generated method stub

}

@Override
public Boolean update() {
    // TODO Auto-generated method stub
    return null;
}

@Override
public Student findById(int id) {
    // TODO Auto-generated method stub
    return null;
}

@Override
public Student findByFirstname(String firstname) {
    // TODO Auto-generated method stub
    return null;
}

@Override
public List<Student> select(int id, String firstname, String lastname,
        String email, int age) {
    // TODO Auto-generated method stub
    return null;
}

@Override
public List<Student> selectAll() {
    // TODO Auto-generated method stub
    return null;
}

}

I have a database on mySql

I am trying to connect to the Student database using SpringDriverManager or BasicdataSource.

How to go about it?

My main application class is:

@SpringBootApplication
@ComponentScan ({"com.sat", "com.sat.controller"} )
@Configuration
@EnableAutoConfiguration
@EnableWebMvc

public class SpringMvc10Application extends SpringBootServletInitializer{


public static void main(String[] args) {


    SpringApplication application = new SpringApplication(SpringMvc10Application.class);
    application.setShowBanner(false);;
                   application.run(args);

    System.out.println("Let's inspect the beans provided by Spring Boot:");


}

}

my Application properties file is

# Spring MVC
#spring.view.prefix:classpath:/templates/
#spring.view.suffix:.html
#spring.view.view-names:jsp/*, html/*
#spring.thymeleaf.view-names:thymeleaf/*

name=Phil, david

# Server
server.port=8088

#override the spring parameter 'create-drop', 'create' creates the schema deleting the previous data
spring.jpa.hibernate.ddl-auto=create

# no sql in the log
spring.jpa.show-sql=false

# mySQL
database.driver=com.mysql.jdbc.Driver
database.url=jdbc:mysql://localhost:3306/student
database.username=root
database.password=root

# THYMELEAF (ThymeleafAutoConfiguration)
spring.thymeleaf.check-template-location=true
#spring.thymeleaf.prefix=classpath:/templates/
spring.thymeleaf.excluded-view-names= # comma-separated list of view names that should be excluded from resolution
#spring.thymeleaf.view-names= well, # comma-separated list of view names that can be resolved
spring.thymeleaf.suffix=.html
spring.thymeleaf.mode=HTML5
spring.thymeleaf.encoding=UTF-8
spring.thymeleaf.content-type=text/html # ;charset=<encoding> is added
spring.thymeleaf.cache= true
# set to false for hot refresh

My simple index.html is where user insert inputs that get stored on the database :

<!DOCTYPE html>
<html> <!--xmlns:th="http://www.thymeleaf.org">-->
    <head>
        <title>Thymeleaf tutorial: exercise 2</title>
        <!--<link rel="stylesheet" href="../../../css/main-static.css" th:href="@{/css/main.css}" />-->
        <meta charset="utf-8" />
    </head>
    <body>

        <h1>Thymeleaf tutorial - Student Info</h1>
        <h2>Student information</h2>



        <input type="text" name="fname" value="" id="firstName"/>
        <input type="text" name="lname" value="" id="lastName"/>

<label for="submit">submit</label><input type="submit" name="submit" value="submit" id="submit"/>

  <span th:text="${name}"> </span>

    </body>

</html>

Now I am confused as I am following lots of tutorials but I don't see much on springBoot. I don't know how to go further.

Please suggest me to the right direction as I am learning Spring. I hope someone would help as I've been stuck on this for days now.

I want to make a connection pool using spring Driver Manager:

@Bean (name = "dataSource")
    public DataSource dm() {

        DriverManagerDataSource dbs = new DriverManagerDataSource();

        dbs.setDriverClassName("jdbc.driverClassName");
        dbs.setUrl("jdbc:mysql://localhost:3306/student");
        dbs.setUsername("root");
        dbs.setPassword("root");

//      dbs.max-active=100;


        return dm();

    }

How to set maxActive Connections, in this?

Now I want to inject this onto my StudentDaoImp class, something like this:

@Override
    public List<Student> select(int id, String firstname, String lastname,
            String email, int age) throws Exception {
        java.sql.Connection con = ds.getConnection();

        // List

        con.close();

        return null;
    }

I get this when I run the project as Spring Boot App:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private javax.sql.DataSource org.springframework.boot.autoconfigure.orm.jpa.JpaBaseConfiguration.dataSource; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in com.sat.SpringMvc10Application: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.sql.DataSource]: Factory method 'dm' threw exception; nested exception is java.lang.IllegalStateException: Could not load JDBC driver class [jdbc.driverClassName]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:334)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1210)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:303)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:299)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMetho

Could someone help me correct the mistakes.

Thanks

Answer 1

You forgot to set the correct driver class name:

java.lang.IllegalStateException: Could not load JDBC driver class [jdbc.driverClassName]

Change the statement

dbs.setDriverClassName("jdbc.driverClassName");

to

dbs.setDriverClassName("com.mysql.jdbc.Driver");

and you should be good to go. Well, at least this exception should be gone. And don't forget to add the driver to your class path.

Edit:

• You have an infinite recursion: dm() calls dm() instead of simply returning dbs.
• You import the wrong @Id annotation in your Student entity (should be the JPA one).
• You seem to implement your DAO and use JDBC to access the database. When using JPA you should use an EntityManager to do that. And in this very case, when using Spring Data JPA (part of your class path), you needn't even implement a DAO using an EntityManager, you can simply define a JPA repository Java interface with the methods you desire.