com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to

com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server. Attempted reconnect 3 times. Giving up.
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    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:408)
    at com.mysql.jdbc.Util.getInstance(Util.java:383)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1023)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:997)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:983)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:928)
    at com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2407)
    at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2328)
    at com.mysql.jdbc.ConnectionImpl.(ConnectionImpl.java:832)
    at com.mysql.jdbc.JDBC4Connection.(JDBC4Connection.java:46)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    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:408)
    at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:417)
    at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:344)
    at java.sql.DriverManager.getConnection(DriverManager.java:664)
    at java.sql.DriverManager.getConnection(DriverManager.java:247)
    at com.company.Main.main(Main.java:11)
Caused by: java.lang.NullPointerException

找了好半天的原因，最后发现是版本问题！

  
        mysql
        mysql-connector-java
        5.1.46
    

 之前用的是：

mysql
mysql-connector-java
5.1.26

解决提示：通过select version（）  查看数据库的版本，然后找对应的connection的版本！