Quick Start
Official Website
http://www.mybatis.org/mybatis-3/
Development Steps
- Add MyBatis coordinates
- Create User data table
- Write User entity class
- Write UserMapper mapping file
- Write SqlMapConfig.xml core file
- Write test class
Create Database and Table
Design the database table according to project requirements and write SQL scripts to create the table structure.
Import MyBatis Dependencies
If using Maven to manage the project, add MyBatis dependencies. Common dependencies include MyBatis core library, MyBatis-Spring (if used with Spring), and database driver.
Project Structure Planning
- Mapper folder: Stores MyBatis mapping interface files
- Mapper XML folder: Stores MyBatis SQL mapping files
- Entity class folder: Java entity classes corresponding to database tables
- Service folder: Encapsulates business logic
- DAO (or Repository) folder: Encapsulates database operations
Configure mybatis-config.xml
- Configure database connection information
- Configure aliases to simplify fully qualified class names of entity classes
- Specify the path to Mapper XML files
Create Entity Classes
Create Java entity classes corresponding to the database table structure. Property names should match table field names (camelCase naming is recommended).
Write Mapper Interface
Create a Mapper interface to declare methods for database operations. Method names correspond one-to-one with ids in the SQL mapping file. Mapper interfaces don’t need implementation classes; MyBatis generates implementations dynamically.
Write Mapper Mapping Files
Common tags include:
- select: Query statements
- insert: Insert statements
- update: Update statements
- delete: Delete statements
Dynamic SQL functionality: Use <if>, <where> and other tags to build complex query conditions.
Load Configuration Files
Use SqlSessionFactoryBuilder to read mybatis-config.xml and build SqlSessionFactory. Obtain SqlSession through SqlSessionFactory and execute Mapper methods.
POM
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>org.example</groupId>
<artifactId>mybatis-test</artifactId>
<version>1.0-SNAPSHOT</version>
<properties>
<maven.compiler.source>8</maven.compiler.source>
<maven.compiler.target>8</maven.compiler.target>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<!--mybatis coordinates-->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.4.5</version>
</dependency>
<!--mysql driver coordinates-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.6</version>
<scope>runtime</scope>
</dependency>
<!--unit test coordinates-->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
<scope>test</scope>
</dependency>
<!--log coordinates-->
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.12</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.22</version>
</dependency>
</dependencies>
</project>Data Table
CREATE TABLE `user_info` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`name` varchar(255) DEFAULT NULL,
`age` int(11) DEFAULT NULL,
`money` bigint(20) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8;Entity Class
package icu.wzk.model;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;
@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
public class UserInfo {
private Long id;
private String username;
private String password;
private Integer age;
}Mapper
<?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="icu.wzk.mapper.UserInfoMapper">
<!-- Query single user info -->
<select id="selectOne" parameterType="java.lang.String" resultType="icu.wzk.model.UserInfo">
SELECT
*
FROM
user_info
WHERE
username = #{username}
</select>
<!-- Query all user info -->
<select id="selectList" resultType="icu.wzk.model.UserInfo">
SELECT
*
FROM
user_info
</select>
</mapper>Core 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>
<properties>
<property name="driverClass" value="com.mysql.cj.jdbc.Driver"/>
<property name="jdbcUrl" value="jdbc:mysql://172.16.1.130:3306/wzk-mybatis?characterEncoding=utf-8"/>
<property name="user" value="hive"/>
<property name="password" value="hive@wzk.icu"/>
</properties>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="${driverClass}"/>
<property name="url" value="${jdbcUrl}"/>
<property name="username" value="${user}"/>
<property name="password" value="${password}"/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="mapper.xml"/>
</mappers>
</configuration>Test Code
package icu.wzk;
import icu.wzk.model.UserInfo;
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 java.io.IOException;
import java.io.InputStream;
import java.util.List;
public class WzkIcu01 {
public static void main(String[] args) throws IOException {
InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder()
.build(resourceAsStream);
SqlSession sqlSession = sqlSessionFactory.openSession();
List<UserInfo> dataList = sqlSession.selectList("icu.wzk.mapper.UserInfoMapper.selectList");
dataList.forEach(System.out::println);
sqlSession.close();
}
}Console Output
24/11/11 15:02:49 DEBUG logging.LogFactory: Logging initialized using 'class org.apache.ibatis.logging.log4j.Log4jImpl' adapter.
24/11/11 15:02:49 DEBUG pooled.PooledDataSource: PooledDataSource forcefully closed/removed all connections.
24/11/11 15:02:49 DEBUG jdbc.JdbcTransaction: Opening JDBC Connection
24/11/11 15:02:49 DEBUG jdbc.JdbcTransaction: Setting autocommit to false on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@e50a6f6]
24/11/11 15:02:49 DEBUG UserInfoMapper.selectList: ==> Preparing: SELECT * FROM user_info
24/11/11 15:02:49 DEBUG UserInfoMapper.selectList: ==> Parameters:
24/11/11 15:02:49 DEBUG UserInfoMapper.selectList: <== Total: 1
UserInfo(id=1, username=wzk, password=icu, age=18)