source scripts/hello.sh 为什么不需要绝对路径就可以用执行脚本呢

老师，我在print前面已经调用的test01这个函数，并给他赋值，为什么运行的时候还是说我打印的内容没有值呢？

好像确实是写错了

请问老师该怎么改，

此行代码 预 打印 false

java.lang.ClassNotFoundException: com.mysql.jdbc.Driver

at java.net.URLClassLoader.findClass(URLClassLoader.java:381)

at java.lang.ClassLoader.loadClass(ClassLoader.java:424)

at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)

at java.lang.ClassLoader.loadClass(ClassLoader.java:357)

at java.lang.Class.forName0(Native Method)

at java.lang.Class.forName(Class.java:264)

at cn.sxt.ThreadLocal.DBUtil.getConnection(DBUtil.java:21)

at cn.sxt.ThreadLocal.DBUtil.main(DBUtil.java:51)

null

老师，在我新建一个工程以后，拷贝的DBUtil.java文件，运行时出现以上的错误，但是我在另外一个工程的DBUtil.java文件就能正常运行，两个一样的文件为什么这个就能出错呢？

老师 为什么我一点登录 没有响应结果  却弹出来一个下载窗口呢

老师你好：下面是我对一些小细节的总结，不知道对不对，请老师指正

    总结：
    (1)多个事物的开启或者执行和查询，不能在同一个查询文本中执行
        
    (2)在其它查询文本中，如果不事先开启事物，直接只查询，这不是对事物的查询，
        
    (3)在其它查询文本中，如果开启事物一次，也查询过一次，当其它事物改变数据时，
    如果当前查询文本没有关闭，开启事物又执行了一次，查询也又执行一次，
    那么等于重新来过，等于是上次开启事物和查询被替代。
    就是说在当前查询文本没有关闭的情况下，不需要多次开启事物，
    否则等于关闭了事物，又重新开启了事物。会导致结果的不一样
        
    (4)若不想新建查询文本，则必须关闭这个查询文本，再次打开执行，才能不受干扰，相当于关闭了事物

老是你好，nonlocal 是否只能在函数嵌套的下一级使用，是否可以捕获两个同级不同函数的局部变量？

还有一个bug就是我对用户角色修改了之后，再次进入分配角色后还是显示用户第一次所有的角色，有些没有角色的用户在分配后，详情里面能看到，但是点击分配后不显示，其次角色什么都不分配的时候也报错

还有这块的数组名我改为其他的就会报空指针异常，数组就拿不到了

求那个什么阿帕奇网站的地址，没找到，难受，谢谢老师

class Student:
    def __init__(self,name,age):
        self.name=name
        self.age=age
    def say_score(self):
        print("{0}的年龄是{1}".format(self.name,self.age))
s1=Student("张三",19)
print(s1.name,s1.age)
s1.say_score()
s2=Student("李四",90)
print(s2.name,s2.age)

老师，,self的作用是把__init__里面的函数，全部做成类里面的公用的局部变量吗。因为def是定义一个函数，正常来讲在第一个def定义的局部变量，在第二个def应该是用不了的。

老师我想实现这样的结果：select u.*,r.rolename from user u,roles r where u.userid = r.user_id and u.userid=1

我在配置文件中应该怎么配置

我自己试了一下，roleid显示为0。只能将Roles类中的roleid这个属性删除吗？

<resultMap id="userAndRolesMapper" type="com.bjsxt.pojo.User">
    <id property="userid" column="userid" />
    <result property="username" column="username" />
    <result property="usersex" column="usersex" />
    <association property="roles" javaType="com.bjsxt.pojo.Roles">
       <!-- <id property="roleid" column="roleid"/>-->
        <result property="rolename" column="rolename"/>
    </association>
</resultMap>
<!--一对一的关联查询：查询userid=1的用户和该用户是什么角色    -->
<select id="selectUserAndRoles" resultMap="userAndRolesMapper" >
    select u.*,r.rolename from user u,roles r where u.userid = r.user_id and u.userid = #{userid}
</select>

老师，安装linux虚拟机试了几次，总是出现这种问题，连不上，没找到引导文件和os，请问怎么解决？

[root@localhost bin]# ./zkCli.shConnecting to localhost:21812021-10-22 05:59:14,768 [myid:] - INFO [main:Environment@98] - Client environment:zookeeper.version=3.6.0--b4c89dc7f6083829e18fae6e446907ae0b1f22d7, built on 02/25/2020 14:38 GMT2021-10-22 05:59:14,776 [myid:] - INFO [main:Environment@98] - Client environment:host.name=localhost2021-10-22 05:59:14,776 [myid:] - INFO [main:Environment@98] - Client environment:java.version=1.8.0_2212021-10-22 05:59:14,787 [myid:] - INFO [main:Environment@98] - Client environment:java.vendor=Oracle Corporation2021-10-22 05:59:14,787 [myid:] - INFO [main:Environment@98] - Client environment:java.home=/usr/local/jdk/jdk/jre2021-10-22 05:59:14,788 [myid:] - INFO [main:Environment@98] - Client environment:java.class.path=/usr/local/zookeepercluster/zookeeper01/bin/../zookeeper-server/target/classes:/usr/local/zookeepercluster/zookeeper01/bin/../build/classes:/usr/local/zookeepercluster/zookeeper01/bin/../zookeeper-server/target/lib/*.jar:/usr/local/zookeepercluster/zookeeper01/bin/../build/lib/*.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/zookeeper-prometheus-metrics-3.6.0.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/zookeeper-jute-3.6.0.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/zookeeper-3.6.0.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/snappy-java-1.1.7.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/slf4j-log4j12-1.7.25.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/slf4j-api-1.7.25.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/simpleclient_servlet-0.6.0.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/simpleclient_hotspot-0.6.0.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/simpleclient_common-0.6.0.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/simpleclient-0.6.0.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/netty-transport-native-unix-common-4.1.45.Final.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/netty-transport-native-epoll-4.1.45.Final.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/netty-transport-4.1.45.Final.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/netty-resolver-4.1.45.Final.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/netty-handler-4.1.45.Final.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/netty-common-4.1.45.Final.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/netty-codec-4.1.45.Final.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/netty-buffer-4.1.45.Final.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/metrics-core-3.2.5.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/log4j-1.2.17.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/json-simple-1.1.1.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/jline-2.11.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/jetty-util-9.4.24.v20191120.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/jetty-servlet-9.4.24.v20191120.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/jetty-server-9.4.24.v20191120.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/jetty-security-9.4.24.v20191120.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/jetty-io-9.4.24.v20191120.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/jetty-http-9.4.24.v20191120.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/javax.servlet-api-3.1.0.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/jackson-databind-2.9.10.3.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/jackson-core-2.9.10.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/jackson-annotations-2.9.10.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/commons-lang-2.6.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/commons-cli-1.2.jar:/usr/local/zookeepercluster/zookeeper01/bin/../lib/audience-annotations-0.5.0.jar:/usr/local/zookeepercluster/zookeeper01/bin/../zookeeper-*.jar:/usr/local/zookeepercluster/zookeeper01/bin/../zookeeper-server/src/main/resources/lib/*.jar:/usr/local/zookeepercluster/zookeeper01/bin/../conf:.:/usr/local/jdk/jdk/lib/dt.jar:/usr/local/jdk/jdk/lib/tools.jar2021-10-22 05:59:14,788 [myid:] - INFO [main:Environment@98] - Client environment:java.library.path=/usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib2021-10-22 05:59:14,788 [myid:] - INFO [main:Environment@98] - Client environment:java.io.tmpdir=/tmp2021-10-22 05:59:14,789 [myid:] - INFO [main:Environment@98] - Client environment:java.compiler=2021-10-22 05:59:14,789 [myid:] - INFO [main:Environment@98] - Client environment:os.name=Linux2021-10-22 05:59:14,789 [myid:] - INFO [main:Environment@98] - Client environment:os.arch=amd642021-10-22 05:59:14,789 [myid:] - INFO [main:Environment@98] - Client environment:os.version=4.18.0-80.el8.x86_642021-10-22 05:59:14,789 [myid:] - INFO [main:Environment@98] - Client environment:user.name=root2021-10-22 05:59:14,789 [myid:] - INFO [main:Environment@98] - Client environment:user.home=/root2021-10-22 05:59:14,789 [myid:] - INFO [main:Environment@98] - Client environment:user.dir=/usr/local/zookeepercluster/zookeeper01/bin2021-10-22 05:59:14,789 [myid:] - INFO [main:Environment@98] - Client environment:os.memory.free=23MB2021-10-22 05:59:14,791 [myid:] - INFO [main:Environment@98] - Client environment:os.memory.max=247MB2021-10-22 05:59:14,791 [myid:] - INFO [main:Environment@98] - Client environment:os.memory.total=29MB2021-10-22 05:59:14,835 [myid:] - INFO [main:ZooKeeper@1005] - Initiating client connection, connectString=localhost:2181 sessionTimeout=30000 watcher=org.apache.zookeeper.ZooKeeperMain$MyWatcher@182decdb2021-10-22 05:59:14,861 [myid:] - INFO [main:X509Util@77] - Setting -D jdk.tls.rejectClientInitiatedRenegotiation=true to disable client-initiated TLS renegotiation2021-10-22 05:59:14,894 [myid:] - INFO [main:ClientCnxnSocket@239] - jute.maxbuffer value is 1048575 Bytes2021-10-22 05:59:14,911 [myid:] - INFO [main:ClientCnxn@1703] - zookeeper.request.timeout value is 0. feature enabled=falseWelcome to ZooKeeper!2021-10-22 05:59:14,960 [myid:localhost:2181] - INFO [main-SendThread(localhost:2181):ClientCnxn$SendThread@1154] - Opening socket connection to server localhost/127.0.0.1:2181.2021-10-22 05:59:14,960 [myid:localhost:2181] - INFO [main-SendThread(localhost:2181):ClientCnxn$SendThread@1156] - SASL config status: Will not attempt to authenticate using SASL (unknown error)JLine support is enabled2021-10-22 05:59:15,292 [myid:localhost:2181] - WARN [main-SendThread(localhost:2181):ClientCnxn$SendThread@1272] - Session 0x0 for sever localhost/127.0.0.1:2181, Closing socket connection. Attempting reconnect except it is a SessionExpiredException.java.net.ConnectException: 拒绝连接 at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method) at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717) at org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:342) at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1262)[zk: localhost:2181(CONNECTING) 0] 2021-10-22 05:59:16,447 [myid:localhost:2181] - INFO [main-SendThread(localhost:2181):ClientCnxn$SendThread@1154] - Opening socket connection to server localhost/127.0.0.1:2181.2021-10-22 05:59:16,448 [myid:localhost:2181] - INFO [main-SendThread(localhost:2181):ClientCnxn$SendThread@1156] - SASL config status: Will not attempt to authenticate using SASL (unknown error)2021-10-22 05:59:16,451 [myid:localhost:2181] - WARN [main-SendThread(localhost:2181):ClientCnxn$SendThread@1272] - Session 0x0 for sever localhost/127.0.0.1:2181, Closing socket connection. Attempting reconnect except it is a SessionExpiredException.java.net.ConnectException: 拒绝连接 at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method) at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717) at org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:342) at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1262)2021-10-22 05:59:17,554 [myid:localhost:2181] - INFO [main-SendThread(localhost:2181):ClientCnxn$SendThread@1154] - Opening socket connection to server localhost/127.0.0.1:2181.2021-10-22 05:59:17,555 [myid:localhost:2181] - INFO [main-SendThread(localhost:2181):ClientCnxn$SendThread@1156] - SASL config status: Will not attempt to authenticate using SASL (unknown error)2021-10-22 05:59:17,556 [myid:localhost:2181] - WARN [main-SendThread(localhost:2181):ClientCnxn$SendThread@1272] - Session 0x0 for sever localhost/127.0.0.1:2181, Closing socket connection. Attempting reconnect except it is a SessionExpiredException.java.net.ConnectException: 拒绝连接 at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method) at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717) at org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:342) at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1262)2021-10-22 05:59:18,658 [myid:localhost:2181] - INFO [main-SendThread(localhost:2181):ClientCnxn$SendThread@1154] - Opening socket connection to server localhost/0:0:0:0:0:0:0:1:2181.2021-10-22 05:59:18,659 [myid:localhost:2181] - INFO [main-SendThread(localhost:2181):ClientCnxn$SendThread@1156] - SASL config status: Will not attempt to authenticate using SASL (unknown error)2021-10-22 05:59:18,659 [myid:localhost:2181] - WARN [main-SendThread(localhost:2181):ClientCnxn$SendThread@1272] - Session 0x0 for sever localhost/0:0:0:0:0:0:0:1:2181, Closing socket connection. Attempting reconnect except it is a SessionExpiredException.java.net.ConnectException: 拒绝连接 at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method) at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717) at org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:342) at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1262)麻烦老师看一下这个是什么错误，启动zookeeper报这个错误

"""这是一个经典的gui程序的写法，使用面向对象的方式"""from tkinter import *from tkinter import messageboxclass Application(Frame): """一个经典的gui程序""" # 定义构造器 def __init__(self,master=None): # 要将父类的构造器定义进来，不然不会被继承（application继承了frame 但他不会自动调用frame的构造器） # super（）代表父类的定义，而不是父类对象 super().__init__(master) self.master = master self.pack() #调用布局管理器，将组件显示在窗口 self.creatWidget() def creatWidget(self): """通过grid布局实现计算器的界面""" # 将文本全部存到元组或列表中，可以存到元组中，因为这些文本是不变的 # 数字可以加引号，也可以不加 btnText = (('MC','M+','M-','MR'), ('C','±','÷','*'), ('7','8','9','-'), ('4','5','6','+'), (1,2,3,'='), (0,'.')) Entry(self).grid(row=0,column=0,columnspan=4,pady=10) # rindex 行的索引 r 这一行 # cindex 对元组再次循环 才能取到一个一个的元素 for rindex,r in enumerate(btnText): for cindex,c in enumerate(r): # 处理等号和零占格的问题 if c == '=': Button(self, text=c, width=2).grid(row=rindex + 1, column=cindex, rowspan=2,sticky=EW) elif c == 0: Button(self, text=c, width=2).grid(row=rindex + 1, column=cindex, columnspan=2,sticky=EW) elif c == '.': # 0占了两列，.就往后移一列 Button(self, text=c, width=2).grid(row=rindex + 1, column=cindex+1, rowspan=2, sticky=EW) else: Button(self,text=c,width=2).grid(row=rindex+1,column=cindex,sticky=EW)if __name__ == '__main__': root = Tk() root.geometry("200x300+200+300") #长400 x 高100 距左边界200 上边界300 root.title("一个经典gui") #定义label时可以删掉 app = Application(master=root) root.mainloop()老师，为啥我的等号没办法跨越两行？