Mybatis入门

1：创建maven工程
2：配置Mybatis坐标，简单的配置如下

<packaging>jar</packaging> //打包方式<dependencies>/*配置mybatis依赖*/<dependency><groupId>org.mybatis</groupId><artifactId>mybatis</artifactId><version>3.4.5</version></dependency>/*单元测试*/<dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>4.10</version><scope>test</scope></dependency>/*配置数据库*/<dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.17</version><scope>runtime</scope></dependency>/*日志*/<dependency><groupId>log4j</groupId><artifactId>log4j</artifactId><version>1.2.12</version></dependency></dependencies>

3：编写实体类
4：编写持久层接口
5：编写SqlMapConfig.xml配置文件
约束文件

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configurationPUBLIC "-//mybatis.org//DTD Config 3.0//EN""http://mybatis.org/dtd/mybatis-3-config.dtd">

配置环境

<configuration><environments default="mysql"><!--配置mysql环境--><environment id="mysql"><!--配置事务类型--><transactionManager type="JDBC"></transactionManager><!--配置连接池--><dataSource type="POOLED"><property name="driver" value="com.mysql.cj.jdbc.Driver"/><property name="url" value="jdbc:mysql://localhost:3306/db3?serverTimezone=UTC"/><property name="username" value="root"/><property name="password" value="1234"/></dataSource></environment></environments><mappers>/*这是xml文件的形式*/<mapper resource="/*持久层接口映射文件的位置加上其文件名*/com/sixs/dao/IUserDao.xml"></mapper></mappers>/*注解的形式*/<mappers><mapper class="/*注解的位置*/com.six.dao.IUserDao"></mapper></mappers>
</configuration>

6：配置持久层接口的映射文件，
约束文件

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd">

配置

/*namespace持久层的全限定类名，去哪找下面的这个findAll的方法*/
<mapper namespace="com.six.dao.IUserDao">/*id是持久层接口中所写的方法，resultType为告诉mybatis将结果封装到哪*/<select id="findAll" resultType="com.six.domain.User">select * from user</select>

7：编写测试类
之前的完成之后就可以去写测试类了

public static void main(String[] args) throws IOException {/*读取配置文件*/InputStream is = Resources.getResourceAsStream("SqlMapConfig.xml");/*创建SqlSessionFactory的构建者对象*/SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();/*使用构建者创建工厂对象*/SqlSessionFactory factory = builder.build(is);/*使用SqlSession生产SqlSession对象*/SqlSession session = factory.openSession();/*使用代理对象执行之前的findAll方法*/IUserDao mapper = session.getMapper(IUserDao.class);List<User> all = mapper.findAll();/*遍历结果集*/for (User user : all) {System.out.println(user);}/*释放资源*/session.close();is.close();}