基于xml的引入外部属性文件

例：配置druid数据源

新建属性文件jdbc.properties

druid.driverClassName=com.mysql.jdbc.Driver
druid.url=jdbc:mysql://localhost:3306/test
druid.username=root
druid.password=root

bean.xml配置

<?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.xsd
                           http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

    <bean id="userService" class="com.xxx.spring.service.UserService"></bean>

    <!--引入外部属性文件-->
    <context:property-placeholder location="classpath:/jdbc.properties"/>
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource" >
        <property name="driverClassName" value="${druid.driverClassName}"></property>
        <property name="url" value="${druid.url}"></property>
        <property name="username" value="${druid.username}"></property>
        <property name="password" value="${druid.password}"></property>
    </bean>
</beans>

import com.alibaba.druid.pool.DruidDataSource;
import com.xxx.spring.service.UserService;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class TestCase {

    @Test
    public void testDruid(){
        ApplicationContext context = new ClassPathXmlApplicationContext("bean.xml");
        DruidDataSource dataSource = context.getBean("dataSource", DruidDataSource.class);
        System.out.println(dataSource.getUrl());//jdbc:mysql://localhost:3306/test

    }
}