MyBatis-Helloworld

一、依赖配置

1.pom.xml

<?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>com</groupId>
    <artifactId>mybatis</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.0</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.15</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <!-- 指定jdk -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

2.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>
    <!--配置数据源-->
    <environments default="development-mysql">
        <environment id="development-mysql">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://192.168.8.136:3306/mybatis"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>

    <!-- mappers：将 SQL 映射文件注册到全局配置中 -->
    <mappers>
        <!-- 引用类路径下的 SQL 映射文件 -->
        <mapper resource="com/dao/MyUserMapper.xml"/>
    </mappers>
</configuration>

二、测试

以 myuser 表为例

1.对应实体类

public class MyUser {
    private Integer id;
    private String name;
    private Integer age;

    public Integer getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

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

    @Override
    public String toString() {
        return "MyUser{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

2.对应接口

import com.bean.MyUser;

public interface MyUserMapper {
    public MyUser selectMyUser(Integer id);
}

3.接口对应的映射文件

<?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">
<!-- namespace 对应接口文件的全路径 -->
<mapper namespace="com.dao.MyUserMapper">
    <!--id 与接口文件方法名对应,resultType 返回类型的全路径-->
    <select id="selectMyUser" resultType="com.bean.MyUser">
      select * from myuser where id = #{id}
    </select>
</mapper>

4.将映射添加到 MyBatis 配置文件 mybatis-config.xml

上面已添加

5.测试方法

import com.bean.MyUser;
import com.dao.MyUserMapper;

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;

public class Main {
    public static void main(String[] args) {
        SqlSession session = null;
        try {
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
            session = sqlSessionFactory.openSession();

            // 不用接口的方式
            // MyUser myUser = session.selectOne("com.dao.MyUserMapper.selectMyUser",1);

            MyUserMapper mapper = session.getMapper(MyUserMapper.class);
            MyUser myUser = (MyUser) mapper.selectMyUser(1);
            System.out.println(myUser);
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (session != null) {
                session.close();
            }
        }
    }
}

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官方文档

GitHub 地址