mybatis系列教程(一)——mybatis配置

红太狼 2022-06-15 06:09 206阅读 0赞

## 项目地址 ##

项目地址：https://code.csdn.net/luo4105/study\_mybatis/

## Mybatis单独配置 ##

为了更好了解mybatis的配置，先完成一个不带spring整合的mybatis配置例子。

使用mybatis的配置如下

1.配置数据源，数据库、账号密码等

2.配置mapper配置文件

3.通过sqlsession获得对应dao接口，操作dao接口。代码

SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsReader("config/mybatis-config.xml"));
    sqlSession = sqlSessionFactory.openSession();
    usersDao = sqlSession.getMapper(UsersDao.class);

## 实现 ##

### Maven依赖 ###

<dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.2</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>6.0.3</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
    </dependencies>

### 项目结构 ###

![Center][]

### Sql建表语句 ###

CREATE TABLE`users`(
     `id` int(11) NOTNULLAUTO_INCREMENT,
     `name`varchar(200) DEFAULT NULL,
     `age` int(11) DEFAULTNULL,
     PRIMARYKEY(`id`)
    ) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8;

INSERT INTO study_mybatis.users(id,name,age) VALUES
    (1,'小王',10)
    ,(2,'荀丽',29)
    ,(3,'明明',12)
    ,(4,'天天',13);

### 配置Mybatis ###

Mybatis配置文件mybatis-config.xml，这里配置的数据源信息和mapper。我用的是mysql-connection-java6.x，6.x版本的数据库连接驱动改为com.mysql.cj.jdbc.Driver，之前是com.mysql.jdbc.Driver。

<?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPEconfigurationPUBLIC"-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
    <configuration>
        <environments default="development">
                <environment id="development">
                    <transactionManager type="JDBC" />
                    <dataSource type="POOLED">
                        <property name="driver" value="com.mysql.cj.jdbc.Driver" />
                        <property name="url" value="jdbc:mysql://localhost:3306/study_mybatis?serverTimezone=GMT&characterEncoding=utf-8"/>
                        <property name="username" value="root" />
                        <property name="password" value="123456" />
                    </dataSource>
                </environment>
        </environments>
    
        <mappers>
            <mapper resource="com/lc/mapper/UsersMapper.xml" />
        </mappers>
    </configuration>

### Mapper、对应接口和model ###

UserMapper.xml

<?xml version="1.0" encoding="utf-8" ?>
    <!DOCTYPEmapperPUBLIC"-//mybatis.org//DTDMapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    <mapper namespace="com.lc.dao.UsersDao">
    
        <select id="getList" resultType="com.lc.model.Users">
            select id, name, age from users
        </select>
    
        <insert id="add" parameterType="com.lc.model.Users">
            INSERT INTO users(name, age)VALUES (#{name}, #{age})
        </insert>
    </mapper>

接口

importcom.lc.model.Users;
    
    import java.util.List;
    
    public interface UsersDao {
        public List<Users> getList();
        public int add(Users users);
    }

实体类：User

public classUser {
       
        private Integer id;
        private String name;
        private Integer age;
        /**
           Getter、setter、toString
        **/
    }

### 测试类 ###

UserDaoTest

importcom.lc.model.Users;
    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.Before;
    import org.junit.Test;
    
    import java.io.IOException;
    import java.util.List;
    
    public class UsersDaoTest {
    
        private UsersDao usersDao;
        private SqlSession sqlSession;
    
        @Before
        public void before() throws IOException {
            SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsReader("config/mybatis-config.xml"));
            sqlSession = sqlSessionFactory.openSession();
            usersDao = sqlSession.getMapper(UsersDao.class);
        }
    
        @Test
        public void getList() throws Exception {
            List<Users> usersList =usersDao.getList();
            for (Users users : usersList) {
                System.out.println(users.toString());
            }
        }
    
        @Test
        public void add() throws Exception {
            Users user = new Users();
            user.setAge(18);
            user.setName("同光尘");
            usersDao.add(user);
            sqlSession.commit();
        }
    }

## 总结 ##

在mybatis的配置文件中，主要配置了两个

dataSource：数据源

mappers：mapper映射文件

在测试类中，实现流程如下

获得sqlsessionFactory

获得SqlSessionFactory对象

获得SqlSession对象

获得UserMapper对象

操作UserMapper对象

进一步猜想

如果我们把数据源和mapper的映射配置在spring的配置文件，