在ego_manage这里我们导入了PageHelper依赖，如果没有这个依赖，数据依然能正常显示，但是会报缺少类的异常。所以我们在这里要添加这个依赖，防止出现异常信息。

老师这个是课程中老师讲的，但是没有说原因呀...

老师，使用了SQL注入器之后，所有的BaseMapper下的方法和AR模式下的方法就都使用不了了，这个问题怎么解决呢

老师您好，def songhua(e): 这个e是有什么作用吗？

btn01.bind( "<Button-1>",songhua)中，"<Button-1>"这个怎么理解？

老师麻烦看一下，这里在处理器 handlers 添加了timed_file，并且在logger里面启用之后会报错

我刚开始不知道哪里错了，然后直接运行老师的，结果发现也是一样出这个错误

老师你好，同样是在苹果电脑操作，我用dir为什么报错呢

百度了一下用ls可以查看子目录

是dir在苹果不能用ls才能查看子目录的意思吗

这里为什么说是返回这个值呢？没搞明白这个，尤其这个（255，0，0）是什么意思啊

老师请问，这里额外还需使用refresh_token的逻辑是什么，带来的优势是什么呢？本身token过期了就再生成一个新的token就好了呀，为什么要用refresh_token获取新token？

<?php
 header("content-type:text/html;charset=utf-8");
 class father{
 public  $pubPro="父类公开的属性";
 protected $protecPro="父类受保护的属性";
 private $priPro="父类私有的属性";

 public function fatherPublicPut(){
 echo $this ->pubPro."<br />";
  echo $this ->protecPro."<br />";
   echo $this ->priPro."<br />";}

protected function fatherProtectedPut(){
 echo $this ->pubPro."<br />";
  echo $this ->protecPro."<br />";
   echo $this ->priPro."<br />";}

private function fatherPrivatePut(){
 echo $this ->pubPro."<br />";
  echo $this ->protecPro."<br />";
   echo $this ->priPro."<br />";}

 }

 class Son extends father{

  public function sonSelfPut(){
  echo $this ->pubPro."<br />";
   echo $this ->protecPro."<br />";
    echo $this ->priPro."<br />";}

 }

 $a =new Son();
 $a ->sonSelfPut()
?>

这样应该是对的吧

老师，boolean=Ture不起作用呢，是现在取消了吗？

这里为什么是泛型接口？没见类里或者哪定义呀？

老师，cookie不是运输session吗，由容器创建session 。浏览器关了 状态cookie没了，为什么sessionid会变呢 ，

如果对L1求导，结果是-1的话，在迭代theta的时候，-ηg，这里的-1就会导致最后一项变成正向的，就达不到减小W的目的了，反而是增大W了

Mybatis_Mybatis入门案例

导入jar包

pojo包

com.bjsxt.pojoUsers {
    String String () {
        }

    (userid) {
        .= userid}

    String () {
        }

    (String username) {
        .= username}

    String () {
        }

    (String usersex) {
        .= usersex}
}

mybatis-cfg.xml文件

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>

    <!--引入properties文件-->
    <properties resource="db.properties"/>

    <!--环境的配置-->
    <environments default="development">
        <environment id="development">
            <!--配置事务-->
            <transactionManager type="JDBC"></transactionManager>
            <!--配置数据源-->
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}"/>
                <property name="url" value="${jdbc.url}"/>
                <property name="username" value="${jdbc.username}"/>
                <property name="password" value="#{jdbc.password}"/>
            </dataSource>
        </environment>
    </environments>
    <!--引入映射配置文件-->
    <mappers>
        <!--使用相对路径方式引入-->
        <mapper resource="com/bjsxt/mapper/UsersMapper.xml"/>
    </mappers>
</configuration>

bd.properties文件

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/bjsxt
jdbc.username=root
jdbc.password=root

mapper包

select * from users

dao包

com.bjsxt.daocom.bjsxt.pojo.Usersjava.io.IOExceptionjava.util.ListUsersDao {
    List<Users> () IOException}

impl包

package com.bjsxt.dao.impl;

import com.bjsxt.dao.UsersDao;
import com.bjsxt.pojo.Users;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;

public class UsersDaoImpl implements UsersDao {
    /**
     * 查询所有用户
     * @return
     */
    @Override
    public List<Users> selectUsersAll() throws IOException {
        //创建SqlSessionFactory对象
        InputStream inputStream = Resources.getResourceAsStream("mybatis-cfg.xml");
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        //获取SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();
        //通过SqlSession对象下的API完成对数据库的操作
        List<Users> list = sqlSession.selectList("com.bjsxt.mapper.UserMapper.selectUsersAll");
        //关闭SqlSession对象
        sqlSession.close();
        return list;
    }
}

test包

com.bjsxt.testcom.bjsxt.dao.UsersDaocom.bjsxt.dao.impl.UsersDaoImplcom.bjsxt.pojo.Usersjava.io.IOExceptionjava.util.ListTest {
    (String[] args)IOException {
        UsersDao usersDao = UsersDaoImpl()List<Users> list = usersDao.selectUsersAll()(Users users:list){
            System..println(users.getUserid()++users.getUsername()++users.getUsersex())}
    }
}

报警

D:\Java\jdk1.8.0_192\bin\java.exe "-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA 2020.1\lib\idea_rt.jar=52913:C:\Program Files\JetBrains\IntelliJ IDEA 2020.1\bin" -Dfile.encoding=UTF-8 -classpath "D:\java\jdk1.8.0_192\jre\lib\charsets.jar;D:\java\jdk1.8.0_192\jre\lib\deploy.jar;D:\java\jdk1.8.0_192\jre\lib\ext\access-bridge-64.jar;D:\java\jdk1.8.0_192\jre\lib\ext\cldrdata.jar;D:\java\jdk1.8.0_192\jre\lib\ext\dnsns.jar;D:\java\jdk1.8.0_192\jre\lib\ext\jaccess.jar;D:\java\jdk1.8.0_192\jre\lib\ext\jfxrt.jar;D:\java\jdk1.8.0_192\jre\lib\ext\localedata.jar;D:\java\jdk1.8.0_192\jre\lib\ext\nashorn.jar;D:\java\jdk1.8.0_192\jre\lib\ext\sunec.jar;D:\java\jdk1.8.0_192\jre\lib\ext\sunjce_provider.jar;D:\java\jdk1.8.0_192\jre\lib\ext\sunmscapi.jar;D:\java\jdk1.8.0_192\jre\lib\ext\sunpkcs11.jar;D:\java\jdk1.8.0_192\jre\lib\ext\zipfs.jar;D:\java\jdk1.8.0_192\jre\lib\javaws.jar;D:\java\jdk1.8.0_192\jre\lib\jce.jar;D:\java\jdk1.8.0_192\jre\lib\jfr.jar;D:\java\jdk1.8.0_192\jre\lib\jfxswt.jar;D:\java\jdk1.8.0_192\jre\lib\jsse.jar;D:\java\jdk1.8.0_192\jre\lib\management-agent.jar;D:\java\jdk1.8.0_192\jre\lib\plugin.jar;D:\java\jdk1.8.0_192\jre\lib\resources.jar;D:\java\jdk1.8.0_192\jre\lib\rt.jar;D:\code\servlet\mybatisdemo\out\production\mybatisdemo;D:\SSM 框架和项目开发 Mybatis\SSM 框架和项目开发 Mybatis\软件\lib\asm-7.1.jar;D:\SSM 框架和项目开发 Mybatis\SSM 框架和项目开发 Mybatis\软件\lib\cglib-3.3.0.jar;D:\SSM 框架和项目开发 Mybatis\SSM 框架和项目开发 Mybatis\软件\lib\ognl-3.2.14.jar;D:\SSM 框架和项目开发 Mybatis\SSM 框架和项目开发 Mybatis\软件\lib\log4j-1.2.17.jar;D:\SSM 框架和项目开发 Mybatis\SSM 框架和项目开发 Mybatis\软件\lib\mybatis-3.5.5.jar;D:\SSM 框架和项目开发 Mybatis\SSM 框架和项目开发 Mybatis\软件\lib\log4j-api-2.13.3.jar;D:\SSM 框架和项目开发 Mybatis\SSM 框架和项目开发 Mybatis\软件\lib\slf4j-api-1.7.30.jar;D:\SSM 框架和项目开发 Mybatis\SSM 框架和项目开发 Mybatis\软件\lib\log4j-core-2.13.3.jar;D:\SSM 框架和项目开发 Mybatis\SSM 框架和项目开发 Mybatis\软件\lib\commons-logging-1.2.jar;D:\SSM 框架和项目开发 Mybatis\SSM 框架和项目开发 Mybatis\软件\lib\javassist-3.27.0-GA.jar;D:\SSM 框架和项目开发 Mybatis\SSM 框架和项目开发 Mybatis\软件\lib\slf4j-log4j12-1.7.30.jar;D:\SSM 框架和项目开发 Mybatis\SSM 框架和项目开发 Mybatis\软件\lib\mysql-connector-java-5.1.48.jar" com.bjsxt.test.Test

log4j:WARN No appenders could be found for logger (org.apache.ibatis.logging.LogFactory).

log4j:WARN Please initialize the log4j system properly.

log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.

Thu Dec 31 13:19:56 CST 2020 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.

Exception in thread "main" org.apache.ibatis.exceptions.PersistenceException: 

### Error querying database.  Cause: java.sql.SQLException: Access denied for user 'root'@'localhost' (using password: YES)

### The error may exist in com/bjsxt/mapper/UsersMapper.xml

### The error may involve com.bjsxt.mapper.UserMapper.selectUsersAll

### The error occurred while executing a query

### Cause: java.sql.SQLException: Access denied for user 'root'@'localhost' (using password: YES)

at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)

at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:149)

at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:140)

at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:135)

at com.bjsxt.dao.impl.UsersDaoImpl.selectUsersAll(UsersDaoImpl.java:27)

at com.bjsxt.test.Test.main(Test.java:13)

Caused by: java.sql.SQLException: Access denied for user 'root'@'localhost' (using password: YES)

at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:965)

at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3933)

at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3869)

at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:864)

at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1707)

at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1217)

at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2189)

at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2220)

at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2015)

at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:768)

at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)

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:425)

at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:385)

at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:323)

at java.sql.DriverManager.getConnection(DriverManager.java:664)

at java.sql.DriverManager.getConnection(DriverManager.java:208)

at org.apache.ibatis.datasource.unpooled.UnpooledDataSource.doGetConnection(UnpooledDataSource.java:224)

at org.apache.ibatis.datasource.unpooled.UnpooledDataSource.doGetConnection(UnpooledDataSource.java:219)

at org.apache.ibatis.datasource.unpooled.UnpooledDataSource.getConnection(UnpooledDataSource.java:95)

at org.apache.ibatis.datasource.pooled.PooledDataSource.popConnection(PooledDataSource.java:432)

at org.apache.ibatis.datasource.pooled.PooledDataSource.getConnection(PooledDataSource.java:89)

at org.apache.ibatis.transaction.jdbc.JdbcTransaction.openConnection(JdbcTransaction.java:139)

at org.apache.ibatis.transaction.jdbc.JdbcTransaction.getConnection(JdbcTransaction.java:61)

at org.apache.ibatis.executor.BaseExecutor.getConnection(BaseExecutor.java:337)

at org.apache.ibatis.executor.SimpleExecutor.prepareStatement(SimpleExecutor.java:86)

at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:62)

at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:325)

at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:156)

at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:109)

at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:89)

at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:147)

... 4 more

Process finished with exit code 1

老师，我在运行下列代码的时候报错了，显示是没有定义f，不知道怎么修改这个代码

代码如下：

try:
    f = open("a.txt","rw")
    table = "琬琰笙梦"
    f.write(table)
except BaseException as e:
        print(e) #输出异常信息
        print('打开异常')
        print('请检查文件格式是否正确')
finally:
    print(f.readline())
    f.close()

报错如下：

Traceback (most recent call last):
  File "C:/pycharm_project/exception_/write_and_read_procedure.py", line 11, in <module>
    print(f.readline())
NameError: name 'f' is not defined

Process finished with exit code 1

老师，帮忙看下是哪错了？最后一个else报错