MySql链接错误提示：Unknown character set: 'utf8mb4'

警告: com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask@50002a2 -- Acquisition Attempt Failed!!! Clearing pending acquires. While trying to acquire a needed new resource, we failed to succeed more than the maximum number of allowed acquisition attempts (30). Last acquisition attempt exception: 

com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown character set: 'utf8mb4'

at sun.reflect.GeneratedConstructorAccessor23.newInstance(Unknown Source)

at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)

at java.lang.reflect.Constructor.newInstance(Constructor.java:423)

at com.mysql.jdbc.Util.handleNewInstance(Util.java:400)

at com.mysql.jdbc.Util.getInstance(Util.java:383)

at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:980)

at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3847)

at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3783)

at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2447)

at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2594)

at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2541)

at com.mysql.jdbc.ConnectionImpl.configureClientCharacterSet(ConnectionImpl.java:1824)

at com.mysql.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:3374)

at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2293)

at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2079)

at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:794)

at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:44)

at sun.reflect.GeneratedConstructorAccessor19.newInstance(Unknown Source)

at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)

at java.lang.reflect.Constructor.newInstance(Constructor.java:423)

at com.mysql.jdbc.Util.handleNewInstance(Util.java:400)

at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:399)

at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:325)

at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:146)

at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:195)

at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:184)

at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:200)

at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1086)

at com.mchange.v2.resourcepool.BasicResourcePool.doAcquireAndDecrementPendingAcquiresWithinLockOnSuccess(BasicResourcePool.java:1073)

at com.mchange.v2.resourcepool.BasicResourcePool.access$800(BasicResourcePool.java:44)

at com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask.run(BasicResourcePool.java:1810)

at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:648)

tomcat启动工程时，提示上面信息的错误提示，通过直接分析，怀疑是数据库的编码问题，但检查编码后发现无法修改该提示。

从网上搜了很多，终于解决。

原来是数据库和链接驱动不匹配造成的问题。

数据库是mySql 6.1.xxx,而驱动是在pom.xml配置的，为5.1.26，两者不匹配。

更换数据库，问题解决。