老师，有两个问题：1.这里的快速插入<!-- -->是使用的什么快捷方式啊；2.这里为什么不能直接写呢？

有没有直接的数据的加载不到。。。。。。。。

老师，学到什么程度可以当爬虫工程师呢？需要达到什么样的水准？

源代码：

package com.bjsxt.TcpIp;

import java.net.InetAddress;
import java.net.UnknownHostException;

public class InetDemo02 {
    public static void main(String[] args) throws UnknownHostException {

        InetAddress inetAddress1 = InetAddress.getByName("www.baidu.com");

        byte[] bytes1 = inetAddress1.getAddress();
        System.out.print("inetAddress1.getAddress(): ");
        for (byte b : bytes1) {
            System.out.print(b + ",");
        }
        System.out.println();
        System.out.println("inetAddress1.getHostAddress(): " + inetAddress1.getHostAddress());
        System.out.println("inetAddress1.getHostName(): " + inetAddress1.getHostName());
        System.out.println("=====================================");
        InetAddress inetAddress2 = InetAddress.getByAddress(bytes1);
        System.out.println("inetAddress2.getHostAddress(): " + inetAddress2.getHostAddress());
        System.out.println("inetAddress2.getHostName(): " + inetAddress2.getHostName());
        System.out.println("=====================================");
    }
}

运行结果：

inetAddress1.getAddress(): -73,-24,-25,-82,
inetAddress1.getHostAddress(): 183.232.231.174
inetAddress1.getHostName(): www.baidu.com
=====================================
inetAddress2.getHostAddress(): 183.232.231.174
inetAddress2.getHostName(): 183.232.231.174
=====================================

疑问：

public static void main(String[] args) {
	//实例化list容器
	List<String>list = new ArrayList<>();
	//添加元素
	boolean flag1 = list.add("oldlu");
	boolean flag2 = list.add("itbz");
	boolean flag3 = list.add("sxt");
	boolean flag4 = list.add("sxt");
	System.out.println(flag1+"\t"+flag2+"\t"+flag3+"\t"+flag4);
	System.out.println("---------------------------");
	System.out.println(list);

老师，最后那一行直接对容器做输出，是不是也能得到容器中的所有元素？

我还没有毕业？这个就不看了

from matplotlib import pyplot as plt
import numpy as np
import seaborn as sns

#获取数据
xiao_mi = np.random.randint(50,100,size=10)  #size为10表示生成10个数
hua_wei = np.random.randint(50,100,size=10)
x = range(10)
#启动设置样式
sns.set()
#填充数据
plt.plot(x,xiao_mi)
plt.plot(x,hua_wei)
#展示数据
plt.show()

老师，这个报错是为什么，seaborn版本已经是0.11了，最新的了

java.lang.IllegalStateException: zookeeper not connected

at org.apache.dubbo.remoting.zookeeper.curator.CuratorZookeeperClient.<init>(CuratorZookeeperClient.java:83) ~[dubbo-remoting-zookeeper-2.7.6.jar:2.7.6]

at org.apache.dubbo.remoting.zookeeper.curator.CuratorZookeeperTransporter.createZookeeperClient(CuratorZookeeperTransporter.java:26) ~[dubbo-remoting-zookeeper-2.7.6.jar:2.7.6]

at org.apache.dubbo.remoting.zookeeper.support.AbstractZookeeperTransporter.connect(AbstractZookeeperTransporter.java:70) ~[dubbo-remoting-zookeeper-2.7.6.jar:2.7.6]

at org.apache.dubbo.remoting.zookeeper.ZookeeperTransporter$Adaptive.connect(ZookeeperTransporter$Adaptive.java) ~[dubbo-common-2.7.6.jar:2.7.6]

at org.apache.dubbo.configcenter.support.zookeeper.ZookeeperDynamicConfiguration.<init>(ZookeeperDynamicConfiguration.java:70) ~[dubbo-2.7.6.jar:2.7.6]

at org.apache.dubbo.configcenter.support.zookeeper.ZookeeperDynamicConfigurationFactory.createDynamicConfiguration(ZookeeperDynamicConfigurationFactory.java:37) ~[dubbo-2.7.6.jar:2.7.6]

at org.apache.dubbo.common.config.configcenter.AbstractDynamicConfigurationFactory.lambda$getDynamicConfiguration$0(AbstractDynamicConfigurationFactory.java:39) ~[dubbo-common-2.7.6.jar:2.7.6]

at java.base/java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1705) ~[na:na]

at org.apache.dubbo.common.config.configcenter.AbstractDynamicConfigurationFactory.getDynamicConfiguration(AbstractDynamicConfigurationFactory.java:39) ~[dubbo-common-2.7.6.jar:2.7.6]

at org.apache.dubbo.common.config.configcenter.DynamicConfiguration.getDynamicConfiguration(DynamicConfiguration.java:223) ~[dubbo-common-2.7.6.jar:2.7.6]

at org.apache.dubbo.config.bootstrap.DubboBootstrap.prepareEnvironment(DubboBootstrap.java:857) ~[dubbo-2.7.6.jar:2.7.6]

at org.apache.dubbo.config.bootstrap.DubboBootstrap.startConfigCenter(DubboBootstrap.java:603) ~[dubbo-2.7.6.jar:2.7.6]

at org.apache.dubbo.config.bootstrap.DubboBootstrap.useRegistryAsConfigCenterIfNecessary(DubboBootstrap.java:671) ~[dubbo-2.7.6.jar:2.7.6]

at org.apache.dubbo.config.bootstrap.DubboBootstrap.initialize(DubboBootstrap.java:509) ~[dubbo-2.7.6.jar:2.7.6]

at org.apache.dubbo.config.bootstrap.DubboBootstrap.start(DubboBootstrap.java:740) ~[dubbo-2.7.6.jar:2.7.6]

at org.apache.dubbo.config.spring.context.DubboBootstrapApplicationListener.onContextRefreshedEvent(DubboBootstrapApplicationListener.java:59) ~[dubbo-2.7.6.jar:2.7.6]

at org.apache.dubbo.config.spring.context.DubboBootstrapApplicationListener.onApplicationContextEvent(DubboBootstrapApplicationListener.java:52) ~[dubbo-2.7.6.jar:2.7.6]

at org.apache.dubbo.config.spring.context.OneTimeExecutionApplicationContextEventListener.onApplicationEvent(OneTimeExecutionApplicationContextEventListener.java:40) ~[dubbo-2.7.6.jar:2.7.6]

at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:172) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:165) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:403) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:360) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:897) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:553) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747) ~[spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) ~[spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) ~[spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) ~[spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) ~[spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at com.bjsxt.provider.ProviderApplication.main(ProviderApplication.java:11) ~[classes/:na]

Caused by: java.lang.IllegalStateException: zookeeper not connected

at org.apache.dubbo.remoting.zookeeper.curator.CuratorZookeeperClient.<init>(CuratorZookeeperClient.java:80) ~[dubbo-remoting-zookeeper-2.7.6.jar:2.7.6]

... 30 common frames omitted

为什么一直连不上？？？？？？？？ 这个报错什么意思？

为啥我的会报错啊

为什么我的tomcat重启以后，自动登录的界面没有   不登录不好使   这句话

package com.bjsxt.web.filter;

import com.bjsxt.commons.Constants;
import com.bjsxt.pojo.Users;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
import java.io.IOException;
@WebFilter(urlPatterns = {"*.do","*.jsp"})
public class UserLoginFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest request=(HttpServletRequest) servletRequest;
        String uri = request.getRequestURI();
        if(uri.indexOf("login.jsp")!=-1 || uri.indexOf("login.do")!=-1 ){
            filterChain.doFilter(servletRequest, servletResponse);
        }else {
            HttpSession session=request.getSession();
            Users users  = (Users) session.getAttribute(Constants.USER_SESSION_KEY);
            if(users!=null){
                filterChain.doFilter(servletRequest, servletResponse);
            }else {
                request.setAttribute(Constants.REQUEST_MSG,"不登录不好使");
                request.getRequestDispatcher("login.jsp").forward(servletRequest, servletResponse);
            }
        }
    }

    @Override
    public void destroy() {

    }
}

可能是什么原因造成没有dubbo节点呢,检查了好几遍,配置的没错啊...

老师这里m.eat()那里，那我给m传参数后，比如Chinese()

那调用函数就是manEat(Chinese())这样，但

为什么Chinese().eat() >>> 类名.方法名这样可以调用？？？？？？？

不是应该实例化一个类对象，p=Chinese()，再调用吗？

老师，请问"utf-8"是什么意思？

看到好多遍了，不太懂