MyBatis - 使用示例（一）单独使用

柔光的暖阳◎ 2023-01-01 02:52 204阅读 0赞

# MyBatis - 使用示例 （一）单独使用 #

> MyBatis 是一款优秀的持久层框架，它支持自定义 SQL、存储过程以及高级映射。MyBatis 免除了几乎所有的 JDBC 代码以及设置参数和获取结果集的工作。MyBatis 可以通过简单的 XML 或注解来配置和映射原始类型、接口和 Java POJO（Plain Old Java Objects，普通老式 Java 对象）为数据库中的记录

越来越多的企业已经将 MyBatis 使用到了正式的生产环境，本系列就先介绍几种简单使用 MyBatis 的方式。

## 一、单独使用 MyBatis 访问数据库 ##

### （一）引入依赖 ###

各位参照的小伙伴们，注意下版本最好一致，避免出现不可预估的问题。

<dependencies>
        
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.6</version>
        </dependency>
        
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
        
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.20</version>
        </dependency>
        
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.12</version>
        </dependency>
        
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.73</version>
        </dependency>
    </dependencies>

### （二）添加mybatis-config.xml ###

**注意：**

> plugins在配置文件中的位置必须符合要求，否则会报错，顺序如下:
> 
> properties?, settings?, typeAliases?, typeHandlers?, objectFactory?,objectWrapperFactory?, plugins?, environments?,databaseIdProvider?, mappers?

<?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>
            
            <setting name="cacheEnabled" value="false" />
            
            <setting name="multipleResultSetsEnabled" value="true" />
            
            <setting name="mapUnderscoreToCamelCase" value="true" />
            
            <setting name="localCacheScope" value="STATEMENT" />
        </settings>
        
        <typeAliases>
            <package name="cn.tzh.mybatisdemo.entity"/>
        </typeAliases>
        
        <environments default="development">
            <environment id="development">
                <transactionManager type="JDBC">
                    <property name="" value=""/>
                </transactionManager>
                
                <dataSource type="UNPOOLED">
                    <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                    <property name="url" value="jdbc:mysql://localhost:3306/gsfy_user?useUnicode=true&characterEncoding=UTF-8&useSSL=false"/>
                    <property name="username" value="user"/>
                    <property name="password" value="password"/>
                </dataSource>
            </environment>
        </environments>
    	
        <mappers>
            <package name="cn.tzh.myabtisdemo.mapper"/>
        </mappers>
    </configuration>

### （三）准备实体类 ###

package cn.tzh.mybatisdemo.entity;
    
    import lombok.Data;
    import java.io.Serializable;
    
    /** * @author tzh * @date 2020/12/28 14:32 */
    @Data
    public class User implements Serializable { 
        private Long id;
        private String userName;
        private Integer age;
        private String phone;
        private String desc;
    }

### （四）创建Mapper接口 ###

package cn.tzh.mybatisdemo.mapper;
    
    import cn.tzh.mybatisdemo.entity.User;
    import org.apache.ibatis.annotations.Param;
    
    /** * @author tzh * @date 2020/12/28 14:29 */
    public interface UserMapper { 
    
        /** * 查询用户 * * @param id id * @return {@link User} * @author tzh * @date 2020/12/30 */
        User selectUser(@Param("id") Long id);
    }

### （五）创建XML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">
    
    <mapper namespace="cn.tzh.mybatisdemo.mapper.UserMapper">
        
        <cache/>
        
        <select id="selectUser" resultType="User">
            select *
            from user
            where id = #{id}
        </select>
    </mapper>

### （六）测试 ###

package cn.tzh.mybatisdemo;
    
    import cn.tzh.mybatisdemo.entity.User;
    import cn.tzh.mybatisdemo.mapper.UserMapper;
    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.junit.Test;
    
    import java.io.IOException;
    import java.io.InputStream;
    
    /** * @author tzh * @date 2020/12/28 14:36 */
    public class MybatisTest { 
    
        @Test
        public void test() throws IOException { 
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); //new DefaultSqlSessionFactory(config);
            SqlSession sqlSession = sqlSessionFactory.openSession(true);
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
            User user = mapper.selectUser(155L);
            System.out.println(user.toString());
        }
    }

\--------------最后感谢大家的阅读，愿大家技术越来越流弊！--------------

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\--------------也希望大家给我点支持，谢谢各位大佬了！！！--------------

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