mybatis Getting started with mybatis Hello world using Spring Boot and Maven

Example

1. Add the necessary dependencies to the project POM (mybatis, and mybatis-spring):

<dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis</artifactId>
    <version>x.x.x</version>
</dependency>
<dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis-spring</artifactId>
    <version>1.3.1-SNAPSHOT</version>
</dependency>

A SqlSessionFactory is needed to create mybatis sessions. Spring allows one to be quickly configured using SqlSessionFactoryBean. Simply define a SqlSessionFactoryBean bean, and give the reference to the DataSource bean:

@Bean
public SqlSessionFactoryBean sqlSessionFactoryBean(DataSource dataSource) {
    SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
    sqlSessionFactoryBean.setDataSource(dataSource);
    return sqlSessionFactoryBean;
}

2. Define a mybatis mapper. The mapper is a java interface that will hold SQL queries and translate method calls into JDBC queries. If a default Spring Boot HSQLDB database is being used, this following query can be created. (There are tables involved; it simply returns a string built using a user-provided parameter).

public interface HelloWorldMapper {

    @Select("VALUES ('Hello ' || #{origin})")
    String getString(@Param("origin") String origin);

} 

3. Register existing mappers so Mybatis and Spring can know about them. Add @MapperScan to the spring java configuration with the name of the "root" package containing the mapper interfaces. This annotation will auto-register the interfaces as spring beans, which can be easily injected anywhere in the application.

    @Autowired
    private HelloWorldMapper helloWorldMapper;

    // invoking the mapper method
    helloWorldMapper.getString("World");

Here's the complete Spring configuration class, with a test invocation of the query:

package com.example;

import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.SqlSessionTemplate;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.SpringBootConfiguration;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.TypeExcludeFilter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.FilterType;

import javax.annotation.PostConstruct;
import javax.sql.DataSource;
import java.lang.annotation.*;

@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan
@MapperScan("com.example")
public class DemoApplication {

    @Autowired
    private HelloWorldMapper helloWorldMapper;

    @Bean
    public SqlSessionFactory sqlSessionFactory(DataSource dataSource) throws Exception {
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(dataSource);
        return (SqlSessionFactory) sqlSessionFactoryBean.getObject();
    }

    @PostConstruct
    public void init() {
        System.out.println(helloWorldMapper.getString("World"));
    }

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }

}