How do I create an SqlSessionFactory object in MyBatis?

The example below shows you how to create MyBatis SqlSessionFactory object using an xml configuration. The steps required is create the configuration file. This file basically contains the connection information to the database and MyBatis configuration such as typeAliases and the mappers.

The next steps is read the configuration file using a org.apache.ibatis.io.Resources class. This information the passes as the argument of the build() method of the SqlSessionFactoryBuilder class. The build() method return an SqlSessionFactory object.

package org.kodejava.example.mybatis;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.io.Reader;

public class SqlSessionFactoryDemo {
    public static void main(String[] args) throws IOException {
        //
        // A resource file for MyBatis configuration.
        //
        String res = "org/kodejava/example/mybatis/Configuration.xml";
        Reader reader = Resources.getResourceAsReader(res);

        //
        // Creates an SqlSessionFactoryBuilder. This builder need only 
        // create one time during the application life time.
        //
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();

        //
        // Creates an instance of SqlSessionFactory. This object can be 
        // used to initiate an SqlSession for querying information from 
        // the mapped query.
        //
        SqlSessionFactory factory = builder.build(reader);
        System.out.println("factory = " + factory);
    }
}

Below is an example of MyBatis configuration file:

<?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>
    <typeAliases>
        <typeAlias alias="record" type="org.kodejava.example.mybatis.domain.Record"/>
    </typeAliases>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost/mediadb"/>
                <property name="username" value="root"/>
                <property name="password" value="welcome"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="org/kodejava/example/mybatis/persistence/RecordMapper.xml"/>
    </mappers>
</configuration>

How do I create MyBatis SqlSession object?

To create an SqlSession you can use the SqlSessionFactory class openSession() method. This method offers some overloaded method that can configure the property of the session. For example we can cofigure the auto-commit-mode and the transaction-isolation-level for the session.

package org.kodejava.example.mybatis;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.kodejava.example.mybatis.domain.Record;

import java.io.IOException;
import java.io.Reader;

public class SqlSessionDemo {
    public static void main(String[] args) throws IOException {
        SqlSessionDemo demo = new SqlSessionDemo();

        // Build an SqlSessionFactory.
        SqlSessionFactory factory = demo.getSessionFactory();

        // Create an SqlSession by using the factory.openSession() method.
        // It is a good practice to use a try-with-resources block when
        // working with an SqlSession. The session will be automatically
        // closes when it finishes the job.
        try (SqlSession session = factory.openSession()) {
            Record record = session.selectOne("getRecord", 1L);
            System.out.println("Record = " + record);
        }
    }

    /**
     * Build an SqlSessionFactory.
     *
     * @return an SqlSessionFactory.
     * @throws IOException when fail to read the configuration file.
     */
    private SqlSessionFactory getSessionFactory() throws IOException {
        Reader reader = Resources.getResourceAsReader("configuration.xml");
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        return builder.build(reader);
    }
}

The directory structure of the code above is:

├── pom.xml
└── src
    └── main
        ├── java
        │   └── org
        │       └── kodejava
        │           └── example
        │               └── mybatis
        │                   ├── SqlSessionDemo.java
        │                   └── domain
        │                       └── Record.java
        └── resources
            ├── configuration.xml
            └── org
                └── kodejava
                   └── example
                        └── mybatis
                            └── mapper
                                └── RecordMapper.xml

For the configuration, mapper and the pojo you can check the following links:

Maven Dependencies

<dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis</artifactId>
    <version>3.4.4</version>
</dependency>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.42</version>
</dependency>