Mybatis从入门到精通——Mybatis快速使用（3）

一、准备工作

1.maven依赖

    <dependencies>
        <!--    mysql驱动    -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.18</version>
        </dependency>

        <!--    junit测试    -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>

        <!--    mybatis    -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.4</version>
        </dependency>


        <!-- 日志相关依赖 -->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.7.10</version>
        </dependency>
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <version>1.1.2</version>
        </dependency>
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-core</artifactId>
            <version>1.1.2</version>
        </dependency>
        
    </dependencies>

2.实体类

public class Person {

    private Integer id;

    private String name;

    private String sex;

    private String telephone;

    private String address;

    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 String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public String getTelephone() {
        return telephone;
    }

    public void setTelephone(String telephone) {
        this.telephone = telephone;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public Integer getAge() {
        return age;
    }

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

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

3.SQL资源

DROP TABLE IF EXISTS `person`;
CREATE TABLE `person` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(30) NOT NULL COMMENT '名字',
  `sex` char(1) NOT NULL DEFAULT '男' COMMENT '性别',
  `telephone` varchar(11) DEFAULT NULL COMMENT '手机号',
  `address` varchar(50) DEFAULT NULL COMMENT '地址',
  `age` tinyint(4) DEFAULT NULL COMMENT '年龄',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1295453 DEFAULT CHARSET=utf8;
 
 
INSERT INTO `person` VALUES ('1', 'xy', '男', '123456', '测试', '18');
INSERT INTO `person` VALUES ('2', 'ceshi', '女', '123456789', '美国', '20');
INSERT INTO `person` VALUES ('3', 'ceshi', '女', '123456789', '美国', '21');

二、Mybatis使用步骤

1.创建配置文件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>

    <settings>
        <!--   使用指定日志实现类     -->
        <setting name="lazyLoadTriggerMethods"  value=""/>
            <setting name="logImpl" value="SLF4J"/>
    </settings>

    <!--环境配置，连接的数据库，这里使用的是MySQL-->
    <environments default="mysql">
        <environment id="mysql">
            <!--指定事务管理的类型，这里简单使用Java的JDBC的提交和回滚设置-->
            <transactionManager type="JDBC"></transactionManager>
            <!--dataSource 指连接源配置，type属性指使用的数据源工厂实现类，此处使用Mybatis提供的连接池-->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"></property>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis_study?serverTimezone=GMT%2B8"></property>
                <property name="username" value="root"></property>
                <property name="password" value="123456"></property>
            </dataSource>
        </environment>
    </environments>

    <!--  映射mapper文件的路径-->
    <mappers>
        <mapper resource="mappers/PersonMapper.xml"></mapper>
    </mappers>
    
</configuration>

2.创建mapper接口

public interface PersonMapper {

    Person selectById(Integer id);
}

3.创建mapper.xml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">
<mapper namespace="com.my.mapper.PersonMapper">
    
    <select id="selectById" parameterType="int" resultType="com.my.entity.Person">
        select * from person where id = #{id}
    </select>

</mapper>

4.创建测试类

public class MybatisTest {

    private SqlSessionFactory sqlSessionFactory;

    @Before
    public void init() throws IOException {
        String resource = "mybatis-config.xml";
        //1.使用mybatis的工具读取配置文件
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
        //2.创建sqlSessionFactory
        sqlSessionFactory = sqlSessionFactoryBuilder.build(inputStream);
        inputStream.close();
    }

    @Test
    public void test() {
        //3.获取sqlSession
        SqlSession sqlSession = sqlSessionFactory.openSession();
        //4.获取mapper接口实现类
        PersonMapper personMapper = sqlSession.getMapper(PersonMapper.class);
        //5.调用方法
        Person person = personMapper.selectById(1);
        System.out.println(person);
        //6.释放资源
        sqlSession.close();
    }
}

5.目录结构