$也可以？

课上讲的是#

centOS7可以吗？                                               

老师，sheet_by_index, get_sheet这两个方法有什么区别呢？

没看明白呀，map.entry是干啥的呀，怎么还用迭代器呀，迭代器为了干啥呀，划红线这几行啥用法语，最后为啥用那个arrays.aslist

ERROR 4924 --- [Create-14313325] com.alibaba.druid.pool.DruidDataSource   : create connection SQLException, url: jdbc:mysql://localhost:3306/test?useUnicode=true&characte rEncoding=utf-8&useSSL=false, errorCode 0, state 01S00 java.sql.SQLException: The server time zone value '�й���׼ʱ��' 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:129) ~[mysql-connector-java-8.0.17.jar:8.0.17] at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97) ~[mysql-connector-java-8.0.17.jar:8.0.17] at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:89) ~[mysql-connector-java-8.0.17.jar:8.0.17] at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:63) ~[mysql-connector-java-8.0.17.jar:8.0.17] at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:73) ~[mysql-connector-java-8.0.17.jar:8.0.17] at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:76) ~[mysql-connector-java-8.0.17.jar:8.0.17] at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:827) ~[mysql-connector-java-8.0.17.jar:8.0.17] at com.mysql.cj.jdbc.ConnectionImpl.

(ConnectionImpl.java:447) ~[mysql-connector-java-8.0.17.jar:8.0.17] at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:237) ~[mysql-connector-java-8.0.17.jar:8.0.17] at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:199) ~[mysql-connector-java-8.0.17.jar:8.0.17] at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1570) ~[druid-1.1.12.jar:1.1.12] at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1636) ~[druid-1.1.12.jar:1.1.12] at com.alibaba.druid.pool.DruidDataSource$CreateConnectionThread.run(DruidDataSource.java:2505) ~[druid-1.1.12.jar:1.1.12] Caused by: com.mysql.cj.exceptions.InvalidConnectionAttributeException: The server time zone value '�й���׼ʱ��' 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) ~[na:1.8.0_131] at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_131] at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_131] at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_131] at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61) ~[mysql-connector-java-8.0.17.jar:8.0.17] at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:85) ~[mysql-connector-java-8.0.17.jar:8.0.17] at com.mysql.cj.util.TimeUtil.getCanonicalTimezone(TimeUtil.java:132) ~[mysql-connector-java-8.0.17.jar:8.0.17] at com.mysql.cj.protocol.a.NativeProtocol.configureTimezone(NativeProtocol.java:2139) ~[mysql-connector-java-8.0.17.jar:8.0.17] at com.mysql.cj.protocol.a.NativeProtocol.initServerSession(NativeProtocol.java:2163) ~[mysql-connector-java-8.0.17.jar:8.0.17] at com.mysql.cj.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:1301) ~[mysql-connector-java-8.0.17.jar:8.0.17] at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:958) ~[mysql-connector-java-8.0.17.jar:8.0.17] at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:817) ~[mysql-connector-java-8.0.17.jar:8.0.17] ... 6 common frames omitted  

老师，我的可以正常进入addUser页面，但是点击确定时添加不进去，报的上边的错误，应该怎么解决?

老师创建完project之后并没有遇到视频中的问题，然后我按照视频后半部分的讲解修改，打开网页的时候是显示无法访问。

然后运行Management.py之后出现这个情况：

点开那个网址后：

老师，这个是什么问题？

根据视频操作的，到这一步时就卡住不动了，关闭重启有logs，但是输入“jps”，显示“-bash:jps:command not found”

这个实战中，可以直接使用后代选择器效果是一样的：

        .nav ul li:hover .list-div{

            display: block;

        }

老师怎么我的运行出错了呢？第一次运行还可以，第二次在运行就不行了

我在运行时候没有将lib包putinto进web-inf目录操作导致404错误，后面操作后就正常了，我记得以前的普通java项目不用这一步操作，现在的web项目是不是都需要这一步

mysql 通过cmd  net权限不足   从服务那边老是启动失败   需要什么操作吗

class ChildClass2 extends FatherClass{
    static{
        System.out.println("静态初始化：ChildClass2");
    }
    public ChildClass2(){
        super();//在一个类中，若是构造方法的第一行没有调用super(...)或者this(...); 那么Java默认都会调用super(),含义是调用父类的无参数构造方法。
        System.out.println("创建ChildClass");
    }
}

为啥不输出上面的？？是

super

继承之前的FatherClass类吗？？可为啥不输出上面的呢

while(str.indexOf('sxt')!=-1) {
            str=str.replace('sxt','xxx');
        }
        console.log(str);

老师，！这里面的！=-1是啥意思？

用while语句奇数累加写不出来，这个要怎么写