创建Mybatis实例

1、在数据库中创建User表

 

2、创建Maven项目

3、导入依赖

    <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.7</version>
        </dependency>
        <dependency>
            <groupId>MysqL</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.2.6</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.6</version>
        </dependency>
    </dependencies>
    <build>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.xml</include>
                </includes>
            </resource>
        </resources>
    </build>

4、创建user的实体类

@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
    private Integer id;
    private String name;
    private String pwd;
}

5、创建生成sqlsession的工具类

public class MybatisUtils {

    private static sqlSessionFactory sqlSessionFactory;



    static {
        InputStream is = null;
        try {
            is = Resources.getResourceAsstream("sqlMapConfig.xml");
            sqlSessionFactory = new sqlSessionFactoryBuilder().build(is);
        } catch (IOException e) {
            e.printstacktrace();
        } finally {
            if (is != null) {
                try {
                    is.close();
                } catch (IOException e) {
                    e.printstacktrace();
                }
            }
        }
    }

    /**
     * 获得sqlSession
     */
    public static sqlSession opensqlSession() throws IOException {
        return sqlSessionFactory.openSession();
    }

    /**
     * 提交释放资源
     */
    public static void commitAndClose(sqlSession sqlSession) {
        if (sqlSession != null) {
            sqlSession.commit();
            sqlSession.close();
        }
    }

    /**
     * 回滚释放资源
     */
    public static void rollbackAndClose(sqlSession sqlSession) {
        if (sqlSession != null) {
            sqlSession.rollback();
            sqlSession.close();
        }
    }
}

6、创建UserMapper接口

public interface UserMapper {

    List<User> findAll();
}

7、创建UserMapper.xml

<?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.study.dao.UserMapper">
    <select id="findAll" resultType="com.study.pojo.User">
        select * from user
    </select>
</mapper>

8、进行测试

    public static void main(String[] args) {
        sqlSession session = MybatisUtils.getSession();
        UserMapper mapper = session.getMapper(UserMapper.class);
        List<User> all = mapper.findAll();
        for (User user : all) {
            System.out.println(user);
        }
    }