为什么“家电”跑到上面去了，咋办

老师我代码一样防火墙也关了结果输出还是这

老师，请问是2019.3.4版本的IDea不可以吗

我通过官网搭建项目时，JavaBoot都是高版本不是跟老师一样的版本

我该怎么解决呢

Traceback (most recent call last):
  File "C:/Users/Administrator/Desktop/untitled/mypy01/TANK.GAME/tk27.py", line 476, in <module>
    MainGame().start_game()
  File "C:/Users/Administrator/Desktop/untitled/mypy01/TANK.GAME/tk27.py", line 325, in start_game
    self.display_enemy_tank()
  File "C:/Users/Administrator/Desktop/untitled/mypy01/TANK.GAME/tk27.py", line 383, in display_enemy_tank
    e_tank.tank_collide_tank(MainGame.my_tank)
  File "C:/Users/Administrator/Desktop/untitled/mypy01/TANK.GAME/tk27.py", line 85, in tank_collide_tank
    if self.live and tank.live:
AttributeError: 'NoneType' object has no attribute 'live'

<canvas id="mycat"></canvas>

<script>

    var ca=document.getElementById("mycat")

var te=.getContext("2d")

te. fillStyle="#FF0000";

te.fillRect(0,0,80,100);

</script>

老师，为什么它不运行呢？没有生成矩形。

localhost拒绝连接怎么搞

老师，我在执行这里的时候报了这个错误，原因是我觉得是编译文件里面没有mapper文件所造成的，但我把对应依赖也给加上了怎么会编译不进去呢？我使用的IDE是idea，请老师帮忙看看

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <parent>
        <groupId>cn.kent</groupId>
        <artifactId>ego-rpc</artifactId>
        <version>1.0-SNAPSHOT</version>
    </parent>

    <artifactId>ego-rpc-service-impl</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>ego-rpc-service-impl</name>

    <repositories>
        <repository>
            <id>maven-ali</id>
            <url>http://maven.aliyun.com/nexus/content/groups/public/</url>
            <releases>
                <enabled>true</enabled>
            </releases>
            <snapshots>
                <enabled>true</enabled>
                <updatePolicy>always</updatePolicy>
                <checksumPolicy>fail</checksumPolicy>
            </snapshots>
        </repository>
    </repositories>

    <dependencies>
        <dependency>
            <groupId>cn.kent</groupId>
            <artifactId>ego-rpc-mapper</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
        <dependency>
            <groupId>cn.kent</groupId>
            <artifactId>ego-rpc-service</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aop</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-tx</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <!-- 连接池 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
        </dependency>
        <!-- mybatis和spring的整合包 -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
        </dependency>
        <!-- 支持mybatis的日志记录 -->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
        </dependency>
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
        </dependency>
        <dependency>
            <groupId>aopalliance</groupId>
            <artifactId>aopalliance</artifactId>
        </dependency>
        <!-- 单元测试 -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <scope>test</scope>
        </dependency>

        <!-- dubbo依赖 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>dubbo</artifactId>
        </dependency>
        <!-- zookeeper客户端依赖 -->
        <dependency>
            <groupId>com.101tec</groupId>
            <artifactId>zkclient</artifactId>
        </dependency>
        <!-- mybatis分页插件 -->
        <dependency>
            <groupId>com.github.pagehelper</groupId>
            <artifactId>pagehelper</artifactId>
        </dependency>
        <!-- Redis客户端 -->
        <dependency>
            <groupId>redis.clients</groupId>
            <artifactId>jedis</artifactId>
        </dependency>
        <!-- Apache的通用工具 -->
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
        </dependency>
        <!-- solr客户端 -->
        <dependency>
            <groupId>org.apache.solr</groupId>
            <artifactId>solr-solrj</artifactId>
        </dependency>
    </dependencies>

    <build>
        <!-- <plugins>
            指定项目的打包插件信息
            <plugin>
                <artifactId>maven-assembly-plugin</artifactId>
                <configuration>
                    指定打包描述文件的位置：相对项目根目录的路径
                    assembly打包的描述文件
                    <descriptor>assembly/assembly.xml</descriptor>
                </configuration>
                <executions>
                    mvn package的时候打包
                    <execution>
                        <id>make-assembly</id>
                        <phase>package</phase>
                        <goals>
                            <goal>single</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            </plugins> -->
        <!-- dubbo加载spring的配置文件的时候，是从META-INF/spring开始查找 -->
        <resources>
            <resource>
                <!-- 指定从哪个文件夹拷贝 -->
                <directory>src/main/resources/spring</directory>
                <!-- 指定将spring配置文件拷贝到jar包中的META-INF/spring目录 -->
                <targetPath>META-INF/spring</targetPath>
                <includes>
                    <include>**/*.xml</include>
                </includes>
            </resource>
            <!-- 其他的文件拷贝到默认的位置 -->
            <resource>
                <!-- 指定从哪个文件夹拷贝 -->
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.xml</include>
                    <include>**/*.properties</include>
                </includes>
            </resource>
        </resources>


    </build>

</project>

printhello()是实例型对象，不应该是不能想函数一样向（）一样调用

但这里我调用了，为什么没有报错

package com.url;
import java.io.BufferedWriter;
import java.io.FileOutputStream;
import java.net.URL;
import org.omg.CORBA.portable.InputStream;
public class TestURL2 {
    /*
     * 网络爬虫
     * (1)从网络上获取资源www.baidu.com
     * (2)存储到本地
     */
 
 //（1）创建URL对象
 URL url=new URL("https://www.baidu.com"); //主页资源
 //（2）获取字节输入流
 InputStream is=url.openStream();
 //（3）缓冲流
 BufferedReader br=new BufferedReader(new InputStreamReader(is,"utf-8"));
 //（4）存储到本地
 BufferedWriter bw=new BufferedWriter(new OutputStreamWriter(new FileOutputStream("index.html","utf-8")));
 //（5）边度边写
 String line =null;
 while((line=br.readLine)!=null) {
  bw.write(line);
  bw.newLine();
  bw.flush();
 }
 //（6）关闭流
 bw.close();
 br.close();
  }  
}

问题:

找不到错误之处

老师，这怎么解决？

想问一下有没有配套的实体书本？。。。。。

老师，我记得课程前面好像没有讲过freemarker...这次突然用Spring整合，看得我有点懵，虽说这个整合的操作上跟jsp没太大区别

什么叫ping命令

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

public class JDBCTest1 {
    public void insertDepartment(int department_id,String department_name,int manager_id,int location_id){
        Connection connection=null;
        Statement state = null;
        try {
            Class.forName("oracle.jdbc.OracleDriver");
            String url="idbc:oracle:thin:localhost:1521:OCLPDB";
            String username="hr";
            String psw="1234";
            Connection conn=DriverManager.getConnection(url, username, psw);
            String sql = "insert into departments values("+department_id+","+department_name+","+manager_id+","+location_id+")";
            state = connection.createStatement();
            int flat = state.executeUpdate(sql);
            System.out.println(flat);
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            if (state!=null) {
                try {
                    state.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
            if (connection!=null) {
                try {
                    connection.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        }

    }

    public static void main(String args[]){
        JDBCTest1 j = new JDBCTest1();
        j.insertDepartment(2,"学习部",0,0);
    }
}

老师，为什么连接不上

MyInteger b =MyInteger. valueOf(100);

老师这个MyInteger.valueOf 是什么意思，方法的调用吗，还是什么别的固定写法。