数据源对象管理Druid和c3p0

第一步导入相应的jar包(maven导入):

    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.2.10.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.2.11</version>
        </dependency>
        <dependency>
            <groupId>com.mchange</groupId>
            <artifactId>c3p0</artifactId>
            <version>0.9.5.2</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.29</version>
        </dependency>
    </dependencies>

第二步在Spring的配置文件中配置DataSource对象:
在配置之前要开context空间；并且使用下面这句配置context空间加载properties文件

<context:property-placeholder location="classpath*:*.properties" system-properties-mode="NEVER"/>
这里的property-placeholder：属性占位符
classpath*是类路径   *表示所依赖的jar中的配置文件
system-properties-modee="NEVER" 表示忽略环境变量中的配置

<?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 https://www.springframework.org/schema/context/spring-context.xsd">
       <context:property-placeholder location="classpath*:*.properties" system-properties-mode="NEVER"/>
    <bean id="druid" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="name" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
        <property name="url" value="${jdbc.url}"/>
        <property name="driverClassName" value="${jdbc.driver}"/>
    </bean>
    <bean id="c3p0" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="dataSourceName" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
        <property name="jdbcUrl" value="${jdbc.url}"/>
        <property name="driverClass" value="${jdbc.driver}"/>
    </bean>
</beans>

配置完之后在写main方法获取连接池对象：

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

import javax.sql.DataSource;
import java.sql.SQLException;

public class MainApp{
    
    public static void main(String[] args) throws SQLException {
    
        ConfigurableApplicationContext appCon=new ClassPathXmlApplicationContext("ApplicationContext.xml");
        DataSource Druid= (DataSource) appCon.getBean("druid");
        DataSource c3p0= (DataSource) appCon.getBean("c3p0");
        System.out.println(Druid.getConnection());
        System.out.println(c3p0.getConnection());

    }
}

这样我们就通过Spring管理第三方数据库连接池，获取到连接池对象。从而获取到Connection对象。