java之c3p0笔记

注意导包：c3p0-0.9.1.2.jar，mysql-connector-java-5.1.39-bin.jar

配置文件（选一个就可以了）：

c3p0.properties

c3p0.driverClass=com.mysql.jdbc.Driver
c3p0.jdbcUrl=jdbc:mysql:///webstudy
c3p0.user=root
c3p0.password=123

c3p0.xml

<c3p0-config>
	<!-- 默认配置，如果没有指定则使用这个配置 -->
	<default-config>
		<!-- 基本配置 -->
		<property name="driverClass">com.mysql.jdbc.Driver</property>
		<property name="jdbcUrl">jdbc:mysql://127.0.0.1:3306/webstudy</property>
		<property name="user">root</property>
		<property name="password">123</property>
	
		<!--扩展配置-->
		<property name="checkoutTimeout">30000</property>
		<property name="idleConnectionTestPeriod">30</property>
		<property name="initialPoolSize">10</property>
		<property name="maxIdleTime">30</property>
		<property name="maxPoolSize">100</property>
		<property name="minPoolSize">10</property>
		<property name="maxStatements">200</property>
	</default-config> 
	
	
	<!-- 命名的配置 -->
	<named-config name="itcast">
		<property name="driverClass">com.mysql.jdbc.Driver</property>
		<property name="jdbcUrl">jdbc:mysql://127.0.0.1:3306/xxxx</property>
		<property name="user">root</property>
		<property name="password">1234</property>
		
		
		<!-- 如果池中数据连接不够时一次增长多少个 -->
		<property name="acquireIncrement">5</property>
		<property name="initialPoolSize">20</property>
		<property name="minPoolSize">10</property>
		<property name="maxPoolSize">40</property>
		<property name="maxStatements">20</property>
		<property name="maxStatementsPerConnection">5</property>
	</named-config>
</c3p0-config> 

案例代码：

package c3p0;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

import org.junit.Test;

import com.mchange.v2.c3p0.ComboPooledDataSource;

public class c3p0 {
	@Test
	public void test(){
		/*
		 *配置文件的名称:c3p0.properties 或者 c3p0-config.xml
		     配置文件的路径:src下
		*/
			
		ComboPooledDataSource ds = new ComboPooledDataSource();//使用默认的配置
		//new ComboPooledDataSource(String configName)//使用命名的配置 若配置的名字找不到,使用默认的配置
		try {
			Connection conn = ds.getConnection();
			PreparedStatement stm = conn.prepareStatement("select * from t_user");
			ResultSet rs = stm.executeQuery();
			while(rs.next()){
				System.out.println("uid:"+rs.getInt(1) +" username:"+rs.getString(2));
			}
			rs.close();
			stm.close();
			conn.close();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}