连接池主要功能,输出连接数据库的连接。内部可以控制存贮多少个连接
// c3po两种配置方式,1代码内嵌式,2是配置文件读取
// 1:默认去classpath路径下找c3po-config.xml文件加载进来
ComboPooledDataSource cpds = new ComboPooledDataSource();
// 2:得到数据库连接
Connection conn = cpds.getConnection();
//以上是c3p0能做的事情
Statement st = conn.createStatement();
int sum = st.executeUpdate("insert user (username)values('1s');");
System.out.println(sum);
/**外部c3po-config.xml文件
* <c3p0-config>
<default-config>
<property name="driverClass">com.mysql.jdbc.Driver</property>
<property name="jdbcUrl">jdbc:mysql://localhost:3306/bookstore</property>
<property name="user">root</property>
<property name="password">root</property>
<default-config>
<c3p0-config>