连接mysql报错：java.lang.ClassCastException: java.math.BigInteger cannot be cast to java.lang.Long

报错：

get data error!java.sql.SQLException: java.lang.ClassCastException: java.math.BigInteger cannot be cast to java.lang.Long
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1074)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:988)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:974)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:919)
    at com.mysql.jdbc.ConnectionImpl.buildCollationMapping(ConnectionImpl.java:1041)
    at com.mysql.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:3481)
    at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2445)
    at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2215)
    at com.mysql.jdbc.ConnectionImpl.(ConnectionImpl.java:813)
    at com.mysql.jdbc.JDBC4Connection.(JDBC4Connection.java:47)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.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:411)
    at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:399)
    at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:334)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at com.geo.test.Test.main(Test.java:21)
Caused by: java.lang.ClassCastException: java.math.BigInteger cannot be cast to java.lang.Long
    at com.mysql.jdbc.ConnectionImpl.buildCollationMapping(ConnectionImpl.java:992)
    ... 15 more

代码无误。

代码：

        String username ="root";
        String pwd = "root";
        String url="jdbc:mysql://localhost:3306/sso_test";
        try {
            Class.forName("com.mysql.jdbc.Driver");        
            Connection connect = DriverManager.getConnection(url,username,pwd);
            Statement stmt = connect.createStatement();
            ResultSet rs = stmt.executeQuery("select username from t_user");
            while (rs.next()) {
                    System.out.println(rs.getString("username"));
                  }
            }
        catch (Exception e) {
            e.printStackTrace();
        }

mysql-connector-java-5.1.21.jar包与mysql数据库版本不匹配。

换成了mysql-connector-java-8.0.11.jar。

再报错：
java.sql.SQLException: The server time zone value '???ú±ê×??±??' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support.
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:127)
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:95)
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:87)
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:61)
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:71)
    at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:76)
    at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:862)
    at com.mysql.cj.jdbc.ConnectionImpl.(ConnectionImpl.java:444)
    at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:230)
    at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:226)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at com.geo.test.Test.main(Test.java:16)
Caused by: com.mysql.cj.exceptions.InvalidConnectionAttributeException: The server time zone value '???ú±ê×??±??' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support.
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
    at java.lang.reflect.Constructor.newInstance(Unknown Source)
    at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:59)
    at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:83)
    at com.mysql.cj.util.TimeUtil.getCanonicalTimezone(TimeUtil.java:128)
    at com.mysql.cj.protocol.a.NativeProtocol.configureTimezone(NativeProtocol.java:2201)
    at com.mysql.cj.protocol.a.NativeProtocol.initServerSession(NativeProtocol.java:2225)
    at com.mysql.cj.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:1391)
    at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:993)
    at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:852)
    ... 6 more

原因：

时间不匹配

修改代码：

String url="jdbc:mysql://localhost:3306/sso_test?useUnicode=true&characterEncoding=utf8&serverTimezone=GMT%2B8&useSSL=false";

解决问题。