jdbc基础 (五) 连接池与数据源:DBCP以及C3P0的使用

#连接设置
driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/day16
username=root
password=123456

#<!-- 初始化连接 -->
initialSize=10

#最大连接数量
maxActive=50

#<!-- 最大空闲连接 -->
maxIdle=20

#<!-- 最小空闲连接 -->
minIdle=5

#<!-- 超时等待时间以毫秒为单位 6000毫秒/1000等于60秒 -->
maxWait=60000


#JDBC驱动建立连接时附带的连接属性属性的格式必须为这样：[属性名=property;] 
#注意："user" 与 "password" 两个属性会被明确地传递，因此这里不需要包含他们。
connectionProperties=useUnicode=true;characterEncoding=utf8

#指定由连接池所创建的连接的自动提交（auto-commit）状态。
defaultAutoCommit=true

#driver default 指定由连接池所创建的连接的只读（read-only）状态。
#如果没有设置该值，则“setReadOnly”方法将不被调用。（某些驱动并不支持只读模式，如：Informix）
defaultReadOnly=

#driver default 指定由连接池所创建的连接的事务级别（TransactionIsolation）。
#可用值为下列之一：（详情可见javadoc。）NONE,READ_UNCOMMITTED, READ_COMMITTED, REPEATABLE_READ, SERIALIZABLE
defaultTransactionIsolation=REPEATABLE_READ

package com.cream.ice.jdbc;

import java.io.InputStream;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

import javax.sql.DataSource;

import org.apache.commons.dbcp2.BasicDataSourceFactory;

/**
 * DBCP工具类
 * DBCP使用的默认适配器方式，当Connection对象调用close()方法时，将Connection对象放回连接池中，实际上并不关闭连接
 * 通过dbcpconfig.properties文件配置数据库、连接池参数
 * 
 * @author ice
 *
 */
public class DBCPUtils {
	
	public static DataSource dataSource;
	
	static {
		try {
			InputStream in = DBCPUtils.class.getClassLoader()
					.getResourceAsStream("dbcpconfig.properties");
			Properties properties = new Properties();
			properties.load(in);
			
			//返回数据源对象
			dataSource = BasicDataSourceFactory.createDataSource(properties);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	
	/**
	 * 获取数据源
	 * @return 数据源
	 */
	public static DataSource getDataSource(){
		return dataSource;
	}

	/**
	 * 从连接池中获取连接
	 * @return 
	 */
	public static Connection getConnection(){
		try {
			return dataSource.getConnection();
		} catch (SQLException e) {
			throw new RuntimeException(e);
		}
	}
	
	/**
	 * 释放资源
	 */
	public static void releaseResources(ResultSet resultSet,
			Statement statement, Connection connection) {

		try {
			if (resultSet != null)
				resultSet.close();
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			resultSet = null;
			try {
				if (statement != null)
					statement.close();
			} catch (SQLException e) {
				e.printStackTrace();
			} finally {
				statement = null;
				try {
					if (connection != null)
						connection.close();
				} catch (SQLException e) {
					e.printStackTrace();
				} finally {
					connection = null;
				}
			}
		}
	}
}

2.C3P0使用

①导入c3p0-0.9.5.1.jar和mchange-commons-java-0.2.10.jar

②配置文件为c3p0-config.xml，内容如下：

<?xml version="1.0" encoding="UTF-8"?>

<c3p0-config>
  <default-config>
    <property name="driverClass">com.mysql.jdbc.Driver</property>
    <property name="jdbcUrl">jdbc:mysql://localhost:3306/jdbc</property>
    <property name="user">root</property>
    <property name="password">123456</property>
    
    <property name="checkoutTimeout">30000</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>

    <user-overrides user="test-user">
      <property name="maxPoolSize">10</property>
      <property name="minPoolSize">1</property>
      <property name="maxStatements">0</property>
    </user-overrides>

  </default-config>

  <!-- This app is massive! -->
  <named-config name="intergalactoApp"> 
    <property name="acquireIncrement">50</property>
    <property name="initialPoolSize">100</property>
    <property name="minPoolSize">50</property>
    <property name="maxPoolSize">1000</property>

    <!-- intergalactoApp adopts a different approach to configuring statement caching -->
    <property name="maxStatements">0</property> 
    <property name="maxStatementsPerConnection">5</property>

    <!-- he's important, but there's only one of him -->
    <user-overrides user="master-of-the-universe"> 
      <property name="acquireIncrement">1</property>
      <property name="initialPoolSize">1</property>
      <property name="minPoolSize">1</property>
      <property name="maxPoolSize">5</property>
      <property name="maxStatementsPerConnection">50</property>
    </user-overrides>
  </named-config>
</c3p0-config>

package com.cream.ice.jdbc;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import javax.sql.DataSource;

import com.mchange.v2.c3p0.ComboPooledDataSource;

/**
 * C3P0工具类
 * DBCP使用动态代理，当Connection对象调用close()方法时，将Connection对象放回连接池中，实际上并不关闭连接
 * 通过c3p0-config.xml文件配置数据库、连接池参数
 * @author ice
 *
 */
public class C3P0Utils {
	/**
	 * 数据源
	 */
	public static ComboPooledDataSource cpDataDataSource = new ComboPooledDataSource();
	
	/**
	 * 获取数据源
	 * @return 数据源
	 */
	public static DataSource getDataSource() {
		return cpDataDataSource;
	}
	
	/**
	 * 从连接池中获取连接
	 * @return 
	 */
	public static Connection getConnection(){
		try {
			return cpDataDataSource.getConnection();
		} catch (SQLException e) {
			throw new RuntimeException(e);
		}
	}
	
	/**
	 * 释放资源
	 */
	public static void releaseResources(ResultSet resultSet,
			Statement statement, Connection connection) {

		try {
			if (resultSet != null)
				resultSet.close();
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			resultSet = null;
			try {
				if (statement != null)
					statement.close();
			} catch (SQLException e) {
				e.printStackTrace();
			} finally {
				statement = null;
				try {
					if (connection != null)
						connection.close();
				} catch (SQLException e) {
					e.printStackTrace();
				} finally {
					connection = null;
				}
			}
		}
	}
}