mycat java连接_mycat使用JDBC连接postgresql报如下异常

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

Last packet sent to the server was 20 ms ago.

at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)

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

at java.lang.reflect.Constructor.newInstance(Constructor.java:526)

at com.mysql.jdbc.Util.handleNewInstance(Util.java:406)

at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1074)

at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2103)

at com.mysql.jdbc.ConnectionImpl.(ConnectionImpl.java:718)

at com.mysql.jdbc.JDBC4Connection.(JDBC4Connection.java:46)

at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)

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

at java.lang.reflect.Constructor.newInstance(Constructor.java:526)

at com.mysql.jdbc.Util.handleNewInstance(Util.java:406)

at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:302)

at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:282)

at java.sql.DriverManager.getConnection(DriverManager.java:571)

at java.sql.DriverManager.getConnection(DriverManager.java:215)

请问是啥问题？1.4-dev版本，直接从master check的代码

mysql驱动使用的是 5.1.6

发现是：SHOW COLLATION 这个命令执行时候报错了。