Spring 中如何使用外部属性文件

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1. 项目结构

db.properties

beans_c3p0.xml

<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-4.0.xsd"><!-- 配置c3p0数据源  这种配置不方便维护<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"><property name="user" value="root"></property><property name="password" value="chuck"></property><property name="driverClass" value="com.mysql.jdbc.Driver"></property><property name="jdbcUrl" value="jdbc:mysql:///test"></property></bean>--><!--~~~~~~~~~~~~~~~~~配置c3p0数据源 ~~~~~~~~~~~~~~~~~~~~~~ --><!-- 导入属性文件 --><context:property-placeholder location="classpath:db.properties" /><bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"><!--使用外部属性文件的属性 --><property name="user" value="${user}"></property><property name="password" value="${password}"></property><property name="driverClass" value="${driverClass}"></property><property name="jdbcUrl" value="${jdbcUrl}"></property></bean></beans>

3. 测试方法：

package com.baidu.c3p0;import java.sql.SQLException;import javax.sql.DataSource;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;public class TestSpringC3P0 {public static void main(String[] args) throws SQLException {ApplicationContext ac = new ClassPathXmlApplicationContext("beans_c3p0.xml");DataSource dataSource = (DataSource) ac.getBean("dataSource");System.out.println(dataSource.getConnection());}}

4. 运行结果：

com.mchange.v2.c3p0.impl.NewProxyConnection@f76eb40

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