IOC操作Bean管理（外部属性文件）

1.直接配置数据库信息

（1）配置德鲁伊druid连接池

（2）引入德鲁伊druid连接池依赖jar包

 <!--直接配置连接池--><bean id = "dataSource" class = "com.alibaba.druid.pool.DruidDataSource"><property name="driverClassName" value=""></property><property name="url" value=""></property><property name="username" value=""></property><property name="password" value=""></property></bean>

填入数据库信息：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"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.xsd"><!--直接配置连接池--><bean id = "dataSource" class = "com.alibaba.druid.pool.DruidDataSource"><property name="driverClassName" value="com.mysql.cj.jdbc.Driver"></property><property name="url" value="jdbc:mysql://localhost:3306/db3"></property><property name="username" value="root"></property><property name="password" value="123456"></property></bean></beans>

2.引入外部属性文件配置数据库连接池

（1）创建外部属性文件，properties格式文件，写数据库信息

prop.driverClass=com.mysql.cj.jdbc.Driver
prop.url=jdbc:mysql://localhost:3306/db3
prop.userName=root
prop.password=8888.216

（2）把外部properties属性文件引入到spring配置文件中

a.引入context名称空间

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns:context="http://www.springframework.org/schema/context"xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"></beans>

b.在spring配置文件使用标签引入外部属性文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns:context="http://www.springframework.org/schema/context"xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"><!--    &lt;!&ndash;直接配置连接池&ndash;&gt;-->
<!--    <bean id = "dataSource" class = "com.alibaba.druid.pool.DruidDataSource">-->
<!--        <property name="driverClassName" value="com.mysql.cj.jdbc.Driver"></property>-->
<!--        <property name="url" value="jdbc:mysql://localhost:3306/db3"></property>-->
<!--        <property name="username" value="root"></property>-->
<!--        <property name="password" value="8888.216"></property>-->
<!--    </bean>--><!--引入外部属性文件--><context:property-placeholder location="classpath:jdbc.properties"/><!--配置连接池--><bean id = "dataSource" class = "com.alibaba.druid.pool.DruidDataSource"><property name="driverClassName" value="${prop.driverClass}"></property><property name="url" value="${prop.url}"></property><property name="username" value="${prop.userName}"></property><property name="password" value="${prop.password}"></property></bean></beans>