1 MyBatis简介
- MyBatis 是支持定制化 SQL、存储过程以及高级映射的优秀的持久层框架
- MyBatis 避免了几乎所有的 JDBC 代码和手动设置参数以及获取结果集
- MyBatis可以使用简单的XML或注解用于配置和原始映射，将接口和Java的POJO（Plain Old Java Objects，普通的Java对象）映射成数据库中的记录
- Mybatis 是一个 半自动的ORM（Object Relation Mapping）框架
2 MyBatis的使用
2.1 开发环境的准备
导入
MyBatis框架的jar包、MySQL驱动包、log4j的jar包
myBatis-3.4.1.jar
mysql-connector-java-5.1.37-bin.jar
log4j.jar
创建MyBatis的核心
(全局)配置文件mybatis-config.xml
<?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>
<properties resource="jdbc.properties"></properties>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC" />
<dataSource type="POOLED">
<property name="driver" value="${jdbc.driver}" />
<property name="url" value="${jdbc.url}" />
<property name="username" value="${jdbc.username}" />
<property name="password" value="${jdbc.password}" />
</dataSource>
</environment>
</environments>
<!-- 引入映射文件 -->
<mappers>
<mapper resource="UserMapper.xml" />
</mappers>
</configuration>
其中的jdbc.properties为jdbc的资源文件，就不具体描述
创建映射文件
xxxMapper.xml,其中的xxx对应创建的每个bean
<?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">
<!--
(1)接口全限定名要和映射文件中的namespace保持一致
(2)接口中的方法名和SQL语句的id保持一致
-->
<mapper namespace="com.prgers.mapper.UserMapper">
<select id="getUserByUid" resultType="com.prgers.bean.User">
select * from user where uid = #{id}
</select>
</mapper>
导入log4j的配置文件, 命名为
log4j.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
<log4j:configuration
xmlns:log4j="http://jakarta.apache.org/log4j/">
<appender name="STDOUT"
class="org.apache.log4j.ConsoleAppender">
<param name="Encoding" value="UTF-8" />
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern"
value="%-5p %d{MM-dd HH:mm:ss,SSS} %m (%F:%L) \n" />
</layout>
</appender>
<logger name="java.sql">
<level value="debug" />
</logger>
<logger name="org.apache.ibatis">
<level value="info" />
</logger>
<root>
<level value="debug" />
<appender-ref ref="STDOUT" />
</root>
</log4j:configuration>
3 MyBatis的初步使用
例子: 通过id查找user的所有信息
InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
SqlSession sqlSession = sqlSessionFactory.openSession();
//getMapper():会通过动态代理动态生成UserMapper的代理实现类
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
User user = userMapper.getUserByUid("1");
System.out.println(user);
