C3P0连接池详解

Bertha 。 2022-03-22 20:42 335阅读 0赞

### 1、概述 ###

C3P0开源免费的连接池。目前使用它的开源项目由=有：Spring、Hibernate等。使用第三方工具需要导入jar包。C3P0使用时还需要添加配置文件c3p0-config.xml

### 2、导入jar包（0.9.2版本需要导入两个jar包） ###

![2019012313163843.png][]

### 3、 配置文件（src/c3p0-config.xml） ###

3.1、命名配置

<c3p0-config>
      
      <named-config name="oracle"> 
            
            <property name="driverClass">com.mysql.jdbc.Driver</property>
            <property name="jdbcUrl">jdbc:mysql://localhost:3306/test</property>
            <property name="user">root</property>
            <property name="password">123456</property>
            
            <property name="acquireIncrement">5</property>
            
            <property name="initialPoolSize">20</property>
            
            <property name="minPoolSize">10</property>
            
            <property name="maxPoolSize">40</property>
            
            <property name="maxStatements">0</property>
            
            <property name="maxStatementsPerConnection">5</property>
      </named-config>
    </c3p0-config>

3.2、默认配置

<c3p0-config>
        
        <default-config>
            <property name="driverClass">com.mysql.jdbc.Driver</property>
    	<property name="jdbcUrl">jdbc:mysql://localhost:3306/test</property>
    	<property name="user">root</property>
    	<property name="password">123456</property>
            <property name="checkoutTimeout">30000</property>
            <property name="idleConnectionTestPeriod">30</property>
    	<property name="initialPoolSize">10</property>
            <property name="minPoolSize">10</property>
    	<property name="maxPoolSize">100</property>
            <property name="maxStatements">200</property>
            <user-overrieds user="test-user">
                <property name="minPoolSize">1</property>
    	    <property name="maxPoolSize">10</property>
                <property name="maxStatements">0</property>
            </user-overrides>
      </default-config>
      
    </c3p0-config>

### 4、常见配置项 ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjA3ODQ1MA_size_16_color_FFFFFF_t_70][]

### 5、编写工具类 ###

C3P0提供核心工具类：ComboPooledDataSource，如果要使用连接池，必须创建该类的实例对象。

\* new ComboPooledDataSource("名称");  使用配置文件“命名配置”    <named-config name = "Oracle">

\* new ComboPooledDataSource();   使用配置文件“默认配置”     <default-config>

public class C3P0Utils {
            //使用默认配置
            //private static ComboPooledDataSource dataSource = new ComboPooledDataSource();
            //使用命名配置
    	private static ComboPooledDataSource dataSource = new ComboPooledDataSource("Oracle");
            
            /**获得数据源（连接池）
             *@return
             */
    	public static DataSource getDataSource() {
    		return dataSource;
    	}
    
            /**获得连接
             *@return
             *@throws SQLException
             */
    	public static Connection getConnection() {
    		try {
    			return dataSource.getConnection();
    		} catch (Exception e) {
    			throw new RuntimeException(e);
    		}
    	}
    }

[2019012313163843.png]: /images/20220323/37e00652091b4de995ca8855b1df53b5.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjA3ODQ1MA_size_16_color_FFFFFF_t_70]: /images/20220323/fbda3822090f4d3eb13d6b03937fc6dc.png