1，首先需要引入两个jar包：c3p0-0.9.1.1.jar mysql-connector-java-5.1.4.jar,然后配置xml，引入命名空间context：
<context:property-placeholder location="classpath:db.properties"/>------
表示引入的文件
<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
<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>
2, 编写外部文件： 并引入到xml中
user=root;
password=1230;
driverclass=com.mysql.jdbc.Driver;
jdbcurl=jdbc:mysql:///test
3，写main方法：
public class property {
public static void main(String[] args) {
ApplicationContext ctx = new ClassPathXmlApplicationContext("bean-properties.xml");
DataSource datasource = (DataSource) ctx.getBean("dataSource");
System.out.println(datasource);
}
}