Spring中配置文件中引用外部文件

src\dayday\conn.java

package dayday;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

/**
 * Created by I am master on 2016/11/29.
 */
public class conn {
    private String user;
    private String password;
    private String driveClass;
    private String jdbcUrl;
    private Connection connection;
    public void setUser(String user){
        this.user=user;
    }
    public void setPassword(String password){
        this.password=password;
    }
    public void setDriveClass(String driveClass){
        this.driveClass=driveClass;
    }
    public void setJdbcUrl(String jdbcUrl){
        this.jdbcUrl=jdbcUrl;
    }
    public Connection getConnection() throws SQLException, ClassNotFoundException {
        Class.forName(driveClass);
        connection= DriverManager.getConnection(jdbcUrl,user,password);
        return connection;
    }
}

src\dayday\Main.java

package dayday;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import java.net.SocketTimeoutException;
import java.sql.SQLException;

/**
 * Created by I am master on 2016/11/28.
 */
public class Main {
    public static void main(String[] args) throws SQLException, ClassNotFoundException {
       ApplicationContext ctx=new ClassPathXmlApplicationContext("beans.xml");
       conn con=ctx.getBean("conn",conn.class);
        System.out.println(con.getConnection());
    }
}

src\db.properties

src\beans.xml

<?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:p="http://www.springframework.org/schema/p"
       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">
    <!--原来的配置方式-->
     <!--<bean id="conn" class="dayday.conn">
           <property name="driveClass" value="com.mysql.jdbc.Driver"></property>
           <property name="user" value="root"></property>
           <property name="password" value="root"></property>
           <property name="jdbcUrl" value="jdbc:mysql://localhost:3306/bank"></property>
     </bean>-->
    <!--通过外部配置文件进行配-->
    <context:property-placeholder location="classpath:db.properties"/>
    <bean id="conn" class="dayday.conn">
        <property name="driveClass" value="${driveClass}"></property>
        <property name="user" value="${user}"></property>
        <property name="password" value="${password}"></property>
        <property name="jdbcUrl" value="${jdbcUrl}"></property>
    </bean>
</beans>

运行结果：
com.mysql.jdbc.JDBC4Connection@17942a1

通过<context:property-placeholder location="classpath:db.properties"/>加入外部配置文件

通过${var}引用外部的属性