spring 配置 Hibernate C3P0 连接池
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Configure Hibernate C3P0 Connection Pooling
提问by Denees
I'm stumbled upon a problem while developing a Web Application based on Struts2 with Spring and Hibernate.
在使用 Spring 和 Hibernate 开发基于 Struts2 的 Web 应用程序时，我偶然发现了一个问题。
When I refresh the site a few times, for example 2-4 times, Hibernate is showing up an exception about Too many connections. I've tried to implement C3P0 Connection pool and have some problems with it
当我刷新站点几次（例如 2-4 次）时，Hibernate 会显示有关Too many connections的异常。我已经尝试实现 C3P0 连接池并且有一些问题
The hibernate.cfg.xmlconfiguration:
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
应用上下文.xml
<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>
The log output is:
日志输出是：
org.hibernate.exception.JDBCConnectionException: Cannot open connection
and:
和：
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Data source rejected establishment of connection, message from server: "Too many connections"
And this is how PROCESSLIST MySQL window looks: http://img844.imageshack.us/img844/3959/be69273cc2.png
这就是 PROCESSLIST MySQL 窗口的外观：http: //img844.imageshack.us/img844/3959/be69273cc2.png
I've set max_sizeof connections to 20, but it seems like it doesn't read the C3P0 configuration from file, cause from the screen we can see that number of connections is higher than 20, or maybe I'm doing something wrong, but where? I really need some help guys, I'll appreciate this, and thanks in advance.
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，因为从屏幕上我们可以看到连接数大于 20，或者我做错了什么，但是哪里？我真的需要一些帮助，我会很感激的，并提前致谢。
回答by UdayKiran Pulipati
Mention these property in your hibernate.cfg.xml file
在 hibernate.cfg.xml 文件中提及这些属性
<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>
Refer this link for better understanding: Configuration Properties
请参阅此链接以获得更好的理解：配置属性
回答by Kristiaan
In your applicationContext, instead of using <bean id="dataSource"
class="org.springframework.jdbc.datasource.DriverManagerDataSource" ...try using <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" ...The C3P0PooledDataSource will create a wrapped database connection using the specified DriverClassName, url, username and password
在您的 applicationContext 中，不是使用<bean id="dataSource"
class="org.springframework.jdbc.datasource.DriverManagerDataSource" ...try using <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" ...The C3P0PooledDataSource 将使用指定的 DriverClassName、url、用户名和密码创建一个包装的数据库连接
