Mapper接口开发需要遵循以下规范:
- Mapper.xml文件中的namespace与mapper接口的类路径相同。
- Mapper接口方法名和Mapper.xml中定义的每个statement的id相同
- Mapper接口方法的输入参数类型和mapper.xml中定义的每个sql 的parameterType的类型相同
- Mapper接口方法的输出参数类型和mapper.xml中定义的每个sql的resultType的类型相同
1.需要的jar包
- spring的jar包
- Mybatis的jar包
- Spring+mybatis的整合包。
- Mysql的数据库驱动jar包。
- 数据库连接池的jar包。
2. SqlMapConfig.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>
<!-- 设置别名 -->
<typeAliases>
<!-- 2. 指定扫描包,会把包内所有的类都设置别名,别名的名称就是类名,大小写不敏感 -->
<package name="cn.itcast.mybatis.pojo" />
</typeAliases>
</configuration>
3. applicationContext.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context" xmlns:p="http://www.springframework.org/schema/p"
xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.0.xsd">
<!-- 加载配置文件 -->
<context:property-placeholder location="classpath:db.properties" />
<!-- 数据库连接池 -->
<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"
destroy-method="close">
<property name="driverClassName" value="${jdbc.driver}" />
<property name="url" value="${jdbc.url}" />
<property name="username" value="${jdbc.username}" />
<property name="password" value="${jdbc.password}" />
<property name="maxActive" value="10" />
<property name="maxIdle" value="5" />
</bean>
<!-- 配置SqlSessionFactory -->
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<!-- 配置mybatis核心配置文件 -->
<property name="configLocation" value="classpath:SqlMapConfig.xml" />
<!-- 配置数据源 -->
<property name="dataSource" ref="dataSource" />
</bean>
<!-- -Mapper动态代理开发 -->
<!-- <bean id="userMapper" class="org.mybatis.spring.mapper.MapperFactoryBean">
<property name="sqlSessionFactory" ref="sqlSessionFactory"></property>
<property name="mapperInterface" value="cn.itcast.mybatis.mapper.UserMapper"></property>
</bean> -->
<!-- -Mapper动态代理开发 不能加id,加了报错 -->
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
<!-- 基本包 -->
<property name="basePackage" value="cn.itcast.mybatis.mapper"></property>
</bean>
</beans>
4.mapper配置
<?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">
<!-- namespace:命名空间,用于隔离sql,还有一个很重要的作用,后面会讲 -->
<mapper namespace="cn.itcast.mybatis.mapper.UserMapper">
<!-- 根据id查询用户 -->
<select id="findUserByID" parameterType="Integer"
resultType="user">
select * from user where id = #{id}
</select>
</mapper>
5.运行
@Test
public void demo1(){
ClassPathXmlApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
UserMapper userMapper = (UserMapper)app.getBean("userMapper");
User user = userMapper.findUserByID(1);
System.out.println(user);
}
@Test
public void demo2(){
ClassPathXmlApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
UserMapper userMapper = app.getBean(UserMapper.class);
User user = userMapper.findUserByID(1);
System.out.println(user);
}