mybatis配置及初步使用

首先要引入mybatis架包 大家可以在mavenRepository中搜索 https://mvnrepository.com

<dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.5.3</version> </dependency> </dependencies>

然后配置链接数据库的数据需要放在jdbc.properties文件中

driverClassName=com.mysql.cj.jdbc.Driver url=jdbc:mysql://localhost/test?useUnicode=true&characterEncoding=UTF8&userSSL=true&serverTimezone=GMT%2B8 uName=root password=111111

下面是mybatis的配置文件，大家可以在官网找到

<?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> <!-- 引入jdbc的配置文件 --> <properties resource="jdbc.properties"></properties> <!-- 配置环境信息 --> <environments default="development"> <environment id="development"> <!-- 事务管理器 --> <transactionManager type="JDBC" /> <!-- 数据源 --> <dataSource type="POOLED"> <property name="driver" value="${driverClassName}" /> <property name="url" value="${url}" /> <property name="username" value="${uName}" /> <property name="password" value="${password}" /> </dataSource> </environment> </environments> <!-- 映射器 --> <mappers> <mapper resource="jee/pk1/UserMapper.xml" /> </mappers> </configuration>

写一个sql语句的接口

package jee.pk1; public interface UserMapper { public User get(int id); }

再写一个查询语句的配置文件。注意接口和配置文件的名字要一致

<?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="jee.pk1.UserMapper"> <select id="get" resultType="jee.pk1.User" parameterType="int"> select * from users where UserId = #{id} </select> </mapper>

主方法：

package jee.pk1; import java.io.IOException; import java.io.InputStream; import org.apache.ibatis.io.Resources; import org.apache.ibatis.session.SqlSession; import org.apache.ibatis.session.SqlSessionFactory; import org.apache.ibatis.session.SqlSessionFactoryBuilder; public class App { public static void main(String[] args) throws IOException { String config = "mybatis-config.xml";// 代表classpath下的配置文件 InputStream is = Resources.getResourceAsStream(config);// 代表classpath下的配置文件的输入流 // SqlSessionFactory的构建器 SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder(); // 构建一个SqlSessionFactory SqlSessionFactory sqlSessionFactory = builder.build(is); // 打开一个SqlSession SqlSession session = null; session = sqlSessionFactory.openSession(); // userMapper是实现了UserMapper接口的一个实例 UserMapper userMapper =session.getMapper(UserMapper.class); User user = userMapper.get(1); System.out.println(user); //关闭session session.close(); //session一定会被关闭 // try(SqlSession session = sqlSessionFactory.openSession()) { // // // userMapper是实现了UserMapper接口的一个实例 // UserMapper userMapper = session.getMapper(UserMapper.class); // // User user = userMapper.get(1); // System.out.println(user); // } } }