MyBatis | Integration with Spring Boot

DB Table

test_table

id	value
1	hoge
2	fuga
3	piyo

Folder Structure

├── build.gradle
├── src/main/
│   └── java/
│   └── sample/mybatis/springboot/
│       └── Main.java
│       └── TestTableMapper.java
└── resources/
    └── application.properties
    └── mybatis-config.xml
    └── TestTableMapper.xml

Source Code

build.gradle

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'org.springframework.boot:spring-boot-gradle-plugin:1.3.1.RELEASE'
    }
}

apply plugin: 'java'
apply plugin: 'spring-boot'

sourceCompatibility = '1.8'
targetCompatibility = '1.8'
compileJava.options.encoding = 'UTF-8'

repositories {
    mavenCentral()
}

dependencies {
    compile 'org.springframework.boot:spring-boot-starter'
    // Include the dependency library file for MyBatis Spring Boot.
    compile 'org.mybatis.spring.boot:mybatis-spring-boot-starter:1.0.0'
    compile 'mysql:mysql-connector-java:5.1.38'
}

application.properties

# Load the MyBatis configuration file.
mybatis.config=mybatis-config.xml

# Configure the data source.
spring.datasource.url=jdbc:mysql://localhost/test
spring.datasource.username=test
spring.datasource.password=test
spring.datasource.driver-class-name=com.mysql.jdbc.Driver

mybatis-config.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
  PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
  "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
 <!-- Data source management is handled by Spring Boot, so it is not written here. -->
  <mappers>
    <mapper resource="TestTableMapper.xml"/>
  </mappers>
</configuration>

TestTableMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
  PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
  "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="sample.mybatis.springboot.TestTableMapper">

  <select id="selectTest" resultType="map">
    select * from test_table
  </select>
</mapper>

TestTableMapper.java

package sample.mybatis.springboot;

import java.util.List;
import java.util.Map;

public interface TestTableMapper {

    List<Map<String, Object>> selectTest();
}

Main.java

package sample.mybatis.springboot;

import java.io.IOException;

import org.mybatis.spring.SqlSessionTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ConfigurableApplicationContext;

@SpringBootApplication
public class Main {

    public static void main(String[] args) throws IOException {
        try (ConfigurableApplicationContext ctx = SpringApplication.run(Main.class, args)) {
            Main m = ctx.getBean(Main.class);
            m.method();
        }
    }

    @Autowired
    private SqlSessionTemplate sqlSession;
    @Autowired
    private TestTableMapper mapper;

    public void method() throws IOException {
        System.out.println("[SqlSessionTemplate]");
        this.sqlSession
            .selectList("sample.mybatis.springboot.TestTableMapper.selectTest")
            .forEach(System.out::println);

        System.out.println("[TestTableMapper]");
        this.mapper
            .selectTest()
            .forEach(System.out::println);
    }
}

Execution Result

[SqlSessionTemplate]
{id=1, value=hoge}
{id=2, value=fuga}
{id=3, value=piyo}

[TestTableMapper]
{id=1, value=hoge}
{id=2, value=fuga}
{id=3, value=piyo}

Description

When using MyBatis with Spring Boot, add mybatis-spring-boot-starter as a dependency.
Next, specify the MyBatis configuration file with the name mybatis.config in the Spring Boot configuration file (application.properties).
Because the data source is managed by Spring Boot, configure it in the Spring Boot settings and do not define it separately in MyBatis.
To access SqlSession, inject SqlSessionTemplate with @Autowired.
- The API of SqlSessionTemplate is the same as SqlSession.
- Unlike SqlSession, it is thread-safe, so it can be used from other threads or DAOs without issue.
If you define a Mapper interface, it can be injected with @Autowired.
- Place the interface in a location scanned by Spring.
- If you annotate the Main class with @MapperScan, you can scan Mapper interfaces in all packages, for example @MapperScan("foo.bar").
- This also injects a thread-safe instance, so it can be used from other threads or DAOs without issue.