<dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.16</version>
        </dependency>

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
 
import javax.sql.DataSource;
 
public class App {
    public static void main(String[] args) {
        ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
        DataSource dataSource = (DataSource) ctx.getBean("dataSource");
        System.out.println(dataSource);
 
    }
}

<!--    管理DruidDataSource對象-->
   <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
           <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
           <property name="url" value="jdbc:mysql://localhost:3306/spring_db"/>
           <property name="username" value="root"/>
           <property name="password" value="root"/>
   </bean>

        <dependency>
            <groupId>c3p0</groupId>
            <artifactId>c3p0</artifactId>
            <version>0.9.1.2</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>

  <!--c3p0連接池對象-->
       <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
           <property name="driverClass" value="com.mysql.jdbc.Driver"/>
           <property name="jdbcUrl" value="jdbc:mysql://localhost:3306/spring_db"/>
           <property name="user" value="root"/>
           <property name="password" value="root"/>
           <property name="maxPoolSize" value="1000"/>
       </bean>

<?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">

<context:property-placeholder location="jdbc.properties"/>

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://127.0.0.1:3306/spring_db
jdbc.username=root
jdbc.password=root

<property name="driverClassName" value="${jdbc.driver}"/>
<property name="url" value="${jdbc.url}"/>
<property name="username" value="${jdbc.username}"/>
<property name="password" value="${jdbc.password}"/>

<context:property-placeholder location="jdbc.properties" system-properties-mode="NEVER"/>

<context:property-placeholder location="jdbc.properties,jdbc2.properties"/>

<context:property-placeholder location="*.properties"/>

<context:property-placeholder location="classpath:*.properties"/>

<context:property-placeholder location="classpath*:*.properties"/>