**********c3p0与hibernate的整合使用*********
1.把hibernate下载包里面的optional文件夹下的3个jar包添加到项目a）c3p0 jar文件是c3p0连接池的核心实现b) mchange-commons-java是c3p0依赖包c）hibernate-c3p0是hibernate整合c3p0使用的一个jar包连接池是可以脱离hibernate单独使用的。其它不用hibernate框架的项目要使用c3p0连接池，只需要c3p0与mchange-commons两个jar包即可单独使用c3p0的时候，一般把相关的配置放置在c3p0.properties文件中或其它名字的配置文件中，配置文件中，一般会有2个层面的配置一个层面是jdbc 链接相关的配置，比如驱动，url，用户名，密码等另一个层面的配置就是连接池的相关配置，比如minPoolsize，maxpoolsize等hibernate整合c3p0使用时，只需要在hibernate.cfg.xml配置文件配置c3p0开头的一些连接池设置就可以了，hibernate使用c3p0的逻辑是a）看到hibernate.cfg.xml文件中有c3p0的相关配置，hibernate知道需要使用c3p0连接池了b）在classpath下查看是否有c3p0相关的jar包c）找到后，加载相关类，得到相关的ConnectionProviderd)    依据ConnectionProvider就可以得到相关的池化了的Jdbc Connection对象在hibernate整合c3p0使用时，只需要配置即可，平时的操作与没有使用c3p0的用法是一样的hibernate的session对象会自动关联c3p0提供的已经池化的Connection对象

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC"-//Hibernate/Hibernate Configuration DTD 3.0//EN""http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration><session-factory><!-- MySQL数据库连接配置 --><property name="connection.driver_class">com.microsoft.sqlserver.jdbc.SQLServerDriver</property><property name="connection.url">jdbc:sqlserver://localhost:1433;databaseName=demo</property><property name="connection.username">sa</property><property name="connection.password"></property><property name="dialect">org.hibernate.dialect.SQLServer2008Dialect</property><!-- 配相关的c3p0的关键词 --><property name="c3p0.minPoolSize">4</property><!-- 设定让hibernate帮我们自动创建表，不设定可以吗？ -->
<!--      <property name="hbm2ddl.auto">create</property>  --><property name="show_sql">true</property><property name="format_sql">true</property><mapping resource="shuang/m2m/ClassInfo_m2m.xml"/></session-factory></hibernate-configuration>

public class ClassInfo {private String cid ;private String name;
}

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC"-//Hibernate/Hibernate Mapping DTD 3.0//EN""http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"><hibernate-mapping package="shuang.m2m"><class name="ClassInfo" table="CLASSINFO"><id name="cid" column="cid"><generator class="assigned"></generator></id><property name="name" ></property></class>
</hibernate-mapping>

package com.nf;import java.sql.Connection;
import java.sql.SQLException;
import java.util.HashSet;
import java.util.List;
import java.util.Set;import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.boot.MetadataSources;
import org.hibernate.boot.registry.StandardServiceRegistry;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.jdbc.Work;import util.HibernateUtil;public class Main {public static void main(String[] args) {SessionFactory sf = HibernateUtil.getSessionFactory();Session s = sf.openSession();s.doWork(new Work(){//接口
@Overridepublic void execute(Connection connection) throws SQLException {System.out.println(connection.getClass().getName());//测试是否连接c3p0池，成功//成功，则显示com.mchange.v2.c3p0.impl.NewProxyConnection
            }});s.close();sf.close();}
}

c3p0.driverClass=com.microsoft.sqlserver.jdbc.SQLServerDriver
c3p0.jdbcUrl=jdbc:sqlserver://localhost:1433;databaseName=demo
c3p0.user=sa
c3p0.password=

package c3p0pool;import java.beans.PropertyVetoException;
import java.sql.Connection;import com.mchange.v2.c3p0.ComboPooledDataSource;public class Main {public static void main(String[] args) throws Exception {
/*      ComboPooledDataSource cpds = new ComboPooledDataSource();cpds.setDriverClass( "com.microsoft.sqlserver.jdbc.SQLServerDriver" ); //loads the jdbc driver            cpds.setJdbcUrl( "jdbc:sqlserver://localhost:1433;databaseName=demo" );cpds.setUser("sa");                                  cpds.setPassword("");  */                                ComboPooledDataSource cpds = new ComboPooledDataSource();Connection conn = cpds.getConnection();System.out.println(conn.getClass().getName());conn.close();}}

package pooldemo;import java.util.ArrayList;
import java.util.List;public class WaterPool {private List<Water> allWaters;public WaterPool(){allWaters = new ArrayList<Water>();allWaters.add(new Water());allWaters.add(new Water());allWaters.add(new Water());}public Water getWater(){Water w = null;if(allWaters.size() >0 ){w= allWaters.remove(0);w.setPool(this);}return w;}public void returnWater(Water w){allWaters.add(w);}public int haiShengXiaDe(){return allWaters.size();}
}

package pooldemo;public class Water {private WaterPool pool;//多对一public void setPool(WaterPool pool) {this.pool = pool;}public void close() {//放回水池里pool.returnWater(this);}
}

package pooldemo;public class PoolTest {public static void main(String[] args) {WaterPool pool = new WaterPool();System.out.println("最开始--" + pool.haiShengXiaDe());Water w = pool.getWater();System.out.println("拿走一个之后--"+ pool.haiShengXiaDe());pool.returnWater(w);//    w.close();System.out.println("调用w的close之后"+pool.haiShengXiaDe());}}