解决Communications link failure due to underlying exception

C3P0增加以下配置信息

//获取connnection时测试是否有效
testConnectionOnCheckin = true
//自动测试的table名称
automaticTestTable=C3P0TestTable

//set to something much less than wait_timeout, prevents connections from going stale   
idleConnectionTestPeriod = 18000  
//set to something slightly less than wait_timeout, preventing 'stale' connections from being handed out   
maxIdleTime = 25000  
//if you can take the performance 'hit', set to "true"   
testConnectionOnCheckout = true