配置Hibernate C3P0连接池

Question

我在使用Spring和Hibernate开发基于Struts2的Web应用程序时偶然发现了一个问题.

当我刷新网站几次,例如2-4次时,Hibernate出现了一个关于太多连接的例外.我试图实现C3P0连接池,并遇到一些问题

---

该hibernate.cfg.xml的配置:

<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/axelle</property>
<property name="hibernate.connection.username">axelle</property>
<property name="hibernate.connection.password">dbpassword</property>
<property name="hibernate.current_session_context_class">thread</property>    

<property name="hibernate.c3p0.min_size">5</property>
<property name="hibernate.c3p0.max_size">20</property>
<property name="hibernate.c3p0.timeout">300</property>
<property name="hibernate.c3p0.max_statements">50</property>
<property name="hibernate.c3p0.idle_test_period">3000</property>

applicationContext.xml中

<bean id="propertyConfigurer"
      class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"
      p:location="classpath:jdbc.properties"/>

<bean id="dataSource"
      class="org.springframework.jdbc.datasource.DriverManagerDataSource"
      p:driverClassName="${jdbc.driverClassName}"
      p:url="${jdbc.url}"
      p:username="${jdbc.username}"
      p:password="${jdbc.password}"
      p:connectionProperties="${jdbc.connectionProperties}"/>

<!-- ADD PERSISTENCE SUPPORT HERE (jpa, hibernate, etc) -->

<bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
    <property name="dataSource" ref="dataSource" />
    <property name="configLocation">
        <value>classpath:hibernate.cfg.xml</value>
    </property>
</bean>

<!-- Transaction manager for a single Hibernate SessionFactory (alternative to JTA) -->
<bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager">
    <property name="sessionFactory">
        <ref local="sessionFactory"/>
    </property>
</bean>

日志输出是:

org.hibernate.exception.JDBCConnectionException: Cannot open connection

和:

Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Data source rejected establishment of connection,  message from server: "Too many connections"

这就是PROCESSLIST MySQL窗口的外观:http://img844.imageshack.us/img844/3959/be69273cc2.png

---

我已经将连接的max_size设置为20,但它似乎没有从文件中读取C3P0配置,因为从屏幕我们可以看到连接数高于20,或者我可能做错了什么,但是哪里？我真的需要一些帮助,我会很感激,并提前感谢.

Answer 1

在hibernate.cfg.xml文件中提到这些属性

    <property name="hibernate.c3p0.acquire_increment">1</property>
    <property name="hibernate.c3p0.idle_test_period">100</property>
    <property name="hibernate.c3p0.max_size">10</property>
    <property name="hibernate.c3p0.max_statements">10</property>
    <property name="hibernate.c3p0.min_size">10</property>
    <property name="hibernate.c3p0.timeout">100</property>

请参阅此链接以获得更好的理解:配置属性