严重: Servlet.service() for servlet [dispatcher] in context with path [/mrbbs] threw exception [Request processing failed; nested exception is org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions.PersistenceException: 

### Error querying database.  Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Could not get JDBC Connection; nested exception is com.alibaba.druid.pool.GetConnectionTimeoutException: wait millis 6001, active 0, maxActive 20

### The error may exist in file [G:\eclipseWorkspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\mrbbs\WEB-INF\classes\com\mrkj\ygl\config\mapping\DictionaryMapper.xml]

### The error may involve com.mrkj.ygl.dao.sys.DictionaryMapper.selectByGroup

### The error occurred while executing a query

### Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Could not get JDBC Connection; nested exception is com.alibaba.druid.pool.GetConnectionTimeoutException: wait millis 6001, active 0, maxActive 20] with root cause

com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Data source rejected establishment of connection,  message from server: "Too many connections"

at sun.reflect.GeneratedConstructorAccessor42.newInstance(Unknown Source)

at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)

at java.lang.reflect.Constructor.newInstance(Unknown Source)

at com.mysql.jdbc.Util.handleNewInstance(Util.java:409)

at com.mysql.jdbc.Util.getInstance(Util.java:384)

at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1013)

at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:987)

at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:973)

at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1112)

at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2506)

at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2539)