c3p0运用

com.mchange.v2.c3p0.ComboPooledDataSource：数据库连接池的一种

C3P0是一个开放源代码的JDBC连接池，它在lib目录中与Hibernate一起发布,包括了实现jdbc3和jdbc2扩展规范说明的Connection 和Statement 池的DataSources 对象。

1.需要的jar包：c3p0-0.9.1.2.jar

1 <dependency>
2     <groupId>c3p0</groupId>
3     <artifactId>c3p0</artifactId>
4     <version>0.9.1.2</version>
5 </dependency>

2.ComboPooledDataSource连接数据库方式：

（1）代码连接：

public class TestCombo{
 2     private ComboPooledDataSource dataSource;    private TestCombo() {
 3         try {
 4             dataSource = new ComboPooledDataSource();
 5             dataSource.setUser(root);
 6             dataSource.setPassword(123456);
 7             dataSource.setJdbcUrl(jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=utf-8");
 8             dataSource.setDriverClass(com.mysql.jdbc.Driver);
 9             dataSource.setInitialPoolSize();
10             dataSource.setAcquireIncrement();
11             dataSource.setMinPoolSize();
12             dataSource.setMaxPoolSize();
13             dataSource.setMaxStatements();
14             dataSource.setMaxIdleTime();
15             dataSource.setIdleConnectionTestPeriod();
16             dataSource.setAcquireRetryAttempts();
17 
18         } catch (Exception e) {
19             throw new RuntimeException(e);
20         }
21     }
22 
23   
24     public Connection getConnection() {
25         try {
26             return dataSource.getConnection();
27         } catch (Exception e) {
28             throw new RuntimeException("can not get sms database connection  ", e);
29         }
30     }
31 
32 }

（2）配置文件连接：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
                        http://www.springframework.org/schema/beans/spring-beans.xsd">
    <!--destroy-method="close"的作用是当数据库连接不使用的时候,就把该连接重新放到数据池中,方便下次使用调用. -->                      
    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close" >
        <property name="driverClass" value="${database.driver}" />
        <property name="jdbcUrl" value="${database.url}" />
        <property name="user" value="${database.username}" />
        <property name="password" value="${database.password}" />
        <property name="loginTimeout" value="3000"></property>
         <!--checkoutTimeout从池中拿未使用的连接，超时设置，如果没有设置，就不超时. -->
        <property name="checkoutTimeout" value="30000"></property>
        <property name="preferredTestQuery" value="select 1 from dual"></property>
         <!--每18000秒检查所有连接池中的空闲连接。Default: 0 -->
        <property name="idleConnectionTestPeriod" value="18000"></property>
         <!--testConnectionOnCheckout:如果设置为true,每次从池中取一个连接，将做一下测试，使用automaticTestTable 或者 preferredTestQuery,做一条查询语句.看看连接好不好用，不好用，就关闭它，重新从池中拿一个. -->
        <property name="testConnectionOnCheckout" value="true"></property>
         <!--连接池中保留的最小连接数。-->   
        <property name="minPoolSize" value="5"></property>
        <!--连接池中保留的最大连接数。--> 
        <property name="maxPoolSize" value="100"></property>
         <!-- 初始化池大小 -->
        <property name="initialPoolSize" value="10"></property>
         <!--当连接池中的连接耗尽的时候c3p0一次同时获取的连接数。 -->
        <property name="acquireIncrement" value="5"></property>
         <!--从数据库获取新连接失败后重复尝试的次数。Default: 30 --> 
        <property name="acquireRetryAttempts" value="30"></property>
        <property name="acquireRetryDelay" value="1000"></property>
         <!--最大空闲时间,3600秒内未使用则连接被丢弃。若为0则永不丢弃。-->   
        <property name="maxIdleTime" value="3600"></property>
    </bean>
    <!--另一数据库连接 -->
    <bean id="dataSourceQuas" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close" >
        <property name="driverClass" value="${quas.database.driver}" />
        <property name="jdbcUrl" value="${quas.database.url}" />
        <property name="user" value="${quas.database.username}" />
        <property name="password" value="${quas.database.password}" />
        <property name="loginTimeout" value="3000"></property>
        <property name="checkoutTimeout" value="30000"></property>
        <property name="preferredTestQuery" value="select 1 from dual"></property>
        <property name="idleConnectionTestPeriod" value="18000"></property>
        <property name="testConnectionOnCheckout" value="true"></property>
        <property name="minPoolSize" value="5"></property>
        <property name="maxPoolSize" value="100"></property>
        <property name="initialPoolSize" value="10"></property>
        <property name="acquireIncrement" value="5"></property>
        <property name="acquireRetryAttempts" value="30"></property>
        <property name="acquireRetryDelay" value="1000"></property>
        <property name="maxIdleTime" value="3600"></property>
    </bean>
    
    
    <bean id="dataSourceCtps" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close" >
        <property name="driverClass" value="${ctps.database.driver}" />
        <property name="jdbcUrl" value="${ctps.database.url}" />
        <property name="user" value="${ctps.database.username}" />
        <property name="password" value="${ctps.database.password}" />
        <property name="loginTimeout" value="3000"></property>
        <property name="checkoutTimeout" value="30000"></property>
        <property name="preferredTestQuery" value="select 1 from dual"></property>
        <property name="idleConnectionTestPeriod" value="18000"></property>
        <property name="testConnectionOnCheckout" value="true"></property>
        <property name="minPoolSize" value="5"></property>
        <property name="maxPoolSize" value="100"></property>
        <property name="initialPoolSize" value="10"></property>
        <property name="acquireIncrement" value="5"></property>
        <property name="acquireRetryAttempts" value="30"></property>
        <property name="acquireRetryDelay" value="1000"></property>
        <property name="maxIdleTime" value="3600"></property>
    </bean> 
    
</beans>            

（3）资源文件设置数据库相关值：database.properties