使用下面的两个类，我尝试连接到一个MySQL数据库。然而，我总是得到这个错误:

Wed Dec 09 22:46:52 CET 2015 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.

这是带有main方法的测试类:

public class TestDatabase {

    public static void main(String[] args) {
        Database db = new Database();
        try {
            db.connect();
        } catch (Exception e) {
            e.printStackTrace();
        }
        db.close();
    }
}

这是数据库类:

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class Database {

    private Connection con;

    public void connect() throws Exception{

        if(con != null) return;

        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            throw new Exception("No database");
        }

        String connectionURL = "jdbc:mysql://localhost:3306/Peoples";

        con = DriverManager.getConnection(connectionURL, "root", "milos23");        
    }

    public void close(){
        if(con != null){
            try {
                con.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}