com.mysql.jdbc.exceptions.jdbc4.CommunicationsException
新建的网站出现如下错误：
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: The last packet successfully received from the server was 58,524,080 milliseconds ago. The last packet sent successfully to the server was 58,524,127 milliseconds ago. is longer than the server configured value of 'wait_timeout'. You should consider either expiring and/or testing connection validity before use in your application, increasing the server configured values for client timeouts, or using the Connector/J connection property 'autoReconnect=true' to avoid this problem.
Caused by: java.net.SocketException: Software caused connection abort: socket write error
网上找来的答案：.
在mysql安装目次下找到my.ini文件中添加超时限制：在该文件最后添加一行：wait_timeout=2880000。如许把之前的超时限制把8小时（28800）扩大为800小时。如许重启了mysql后再在此中输入号令：show global variables like "wait_timeout";查看超时是否已批改为：2880000。重启tomcat（若是已启动），OK。
1
解决办法:从common pool的配置参数来解决:
<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
<property name="driverClassName">
<value>${db.driver}</value>
</property>
<property name="url">
<value>${db.url}</value>
</property>
<property name="username">
<value>${db.user}</value>
</property>
<property name="password">
<value>${db.password}</value>
</property>
<property name="maxActive">
<value>100</value>
</property>
<property name="maxIdle">
<value>50</value>
</property>
<property name="maxWait">
<value>10000</value>
</property>
<property name="timeBetweenEvictionRunsMillis">
<value>3600000</value><!--1 hours-->
</property>
<!--
<property name="minEvictableIdleTimeMillis">
<value>20000</value>
</property>
-->
<property name="testWhileIdle">
<value>true</value>
</property>
<property name="validationQuery">
<value>select 1 from dual</value>
</property>
</bean>
使用上述的三个红色的参数,就可以避免这个问题.这三个参数的意义:
timeBetweenEvictionRunsMillis:启动connection校验定时器,定时器运行时间间隔就是timeBetweenEvictionRunsMillis的值.默认为-1,表示不启动定时器,这里设定为1小时,只要小于mysql的wait_timeout就可以了
testWhileIdle: true,表示检查idle的connection,false为不检查
validationQuery:用于检查connection的sql语句.
这只是一种方法,另外的几种方法:
timeBetweenEvictionRunsMillis+minEvictableIdleTimeMillis:这种方式不检查Connection的有效性,而是检查连接的空闲时间,大于minEvictableIdleTimeMillis就清除.
<property name="timeBetweenEvictionRunsMillis">
<value>3600000</value><!--1 hours-->
</property>
<property name="minEvictableIdleTimeMillis">
<value>120000</value><!--connection的空闲时间大于这个值,就直接被关闭,并从连接池中删除-->
</property>
如果不喜欢用定时器,也可以配置testOnBorrow+validationQuery参数:每次从连接池取参数都会校验连接的有效性.实际上这种方式性能会比定时器差些.
<property name="testOnBorrow">
<value>true</value>
</property>
<property name="validationQuery">
<value>select 1 from dual</value>
</property>
另外,也可以用testOnReturn+validationQuery,不过未必会解决问题:这表示每次使用完连接,归还连接池的时候检查连接的有效性,这有可能导致使用一次无效的连接,最好不要用.
上面的几种方法可以合并使用,只是检查的点多了,未必是好事.