数据库连接池 - 码农教程

HTTP Status 500 - Could not open connection
type Exception report
message Could not open connection
description The server encountered an internal error that prevented it from fulfilling this request.
exception
org.hibernate.exception.GenericJDBCException: Could not open connection
org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:54)
......
......
 
 
root cause
java.sql.SQLException: An attempt by a client to checkout a Connection has timed out.
com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:106)
com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:65)
com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:527)
com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:128)
......
......
 
 
 
root cause
com.mchange.v2.resourcepool.TimeoutException: A client timed out while waiting to acquire a resource from com.mchange.v2.resourcepool.BasicResourcePool@6df3d083 -- timeout at awaitAvailable()
com.mchange.v2.resourcepool.BasicResourcePool.awaitAvailable(BasicResourcePool.java:1317)
com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:557)
com.mchange.v2.resourcepool.BasicResourcePool.checkoutResource(BasicResourcePool.java:477)
com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:525)
com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:128)
org.hibernate.service.jdbc.connections.internal.DatasourceConnectionProviderImpl.getConnection(DatasourceConnectionProviderImpl.java:141)
........
........

多次操作数据库后，会报出以上 could not open connection 错误，原因为没有配置数据库的连接池的最大最小连接数。h<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">

    <property name="driverClass" value="${jdbc.driverClass}"></property>
    <property name="jdbcUrl" value="${jdbc.jdbcUrl}"></property>
    <property name="user" value="${jdbc.user}"></property>
    <property name="password" value="${jdbc.password}"></property>
    <property name="maxPoolSize" value="100"></property>
    <property name="minPoolSize" value="20"></property>
    <property name="checkoutTimeout" value="120"></property>
</bean>

以上是在spring中配置的代码，也可以放在properties文件中。