### Error querying database.  Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Could not get JDBC Connection; nested exception is java.sql.SQLException: An attempt by a client to checkout a Connection has timed out.

### The error may exist in file [E:\workspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\seckill\WEB-INF\classes\mapper\SeckillDao.xml]

### The error may involve org.seckill.dao.SeckillDao.queryAll

### The error occurred while executing a query

### Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Could not get JDBC Connection; nested exception is java.sql.SQLException: An attempt by a client to checkout a Connection has timed out.] with root cause

com.mchange.v2.resourcepool.TimeoutException: A client timed out while waiting to acquire a resource from com.mchange.v2.resourcepool.BasicResourcePool@fff09ff -- timeout at awaitAvailable()

这是什么原因，http://localhost:8080/seckill/可成功出现index页面，但http://localhost:8080/seckill/seckill和http://localhost:8080/seckill/seckill/list分别出现404个505错误