数据库连接问题

Question

Caused by: org.apache.ibatis.exceptions.PersistenceException: 

### 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 [D:\JavaSoftware\maven\code\seckill\target\classes\mapper\SeckillDao.xml]

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

### 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.

at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)

at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:122)

at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:113)

at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:73)

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

at java.lang.reflect.Method.invoke(Method.java:498)

at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:386)

... 34 more

Caused by: 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.

at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:80)

at org.mybatis.spring.transaction.SpringManagedTransaction.openConnection(SpringManagedTransaction.java:82)

at org.mybatis.spring.transaction.SpringManagedTransaction.getConnection(SpringManagedTransaction.java:68)

at org.apache.ibatis.executor.BaseExecutor.getConnection(BaseExecutor.java:315)

at org.apache.ibatis.executor.SimpleExecutor.prepareStatement(SimpleExecutor.java:75)

at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:61)

at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:303)

at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:154)

at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:102)

at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:82)

at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:120)

... 41 more

Caused by: java.sql.SQLException: An attempt by a client to checkout a Connection has timed out.

at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:106)

at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:65)

at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:527)

at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:128)

at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:111)

at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:77)

... 51 more

Caused by: com.mchange.v2.resourcepool.TimeoutException: A client timed out while waiting to acquire a resource from com.mchange.v2.resourcepool.BasicResourcePool@771a660 -- timeout at awaitAvailable()

at com.mchange.v2.resourcepool.BasicResourcePool.awaitAvailable(BasicResourcePool.java:1317)

at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:557)

at com.mchange.v2.resourcepool.BasicResourcePool.checkoutResource(BasicResourcePool.java:477)

at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:525)

... 54 more

Answer 1

是Mybatis在执行sql语句的时候报错，没有一个叫queryById的字段对应数据表，你可以看下日志中提到的mappers.xml文件中的SQL语句中的字段名和数据表中的是否一致，往往都是这里出问题。mappers.xml文件中只要有一个字段不正确就会造成数据库链接异常的问题！望采纳

Answer 2

不能获得jdbc连接。看配置文件和jar包导入没。