为什么文件重新指定的编码格式改完了还是乱码

使用xml文件配置网页报500错误是咋回事，老师能帮忙看看嘛

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0"
         metadata-complete="false">
    <context-param>
        <param-name>key1</param-name>
        <param-value>BJSXT</param-value>
    </context-param>
    <context-param>
        <param-name>key2</param-name>
        <param-value>BJSXT</param-value>
    </context-param>
    <servlet>
        <servlet-name>demoServlet</servlet-name>
        <servlet-class>com.example.demo.DemoServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>demoServlet</servlet-name>
        <url-pattern>/demo.do</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>getRequestDataServlet</servlet-name>
        <servlet-class>com.example.demo.GetRequestDataServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>getRequestDataServlet</servlet-name>
        <url-pattern>/getinfo.do</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>getRequestHeaderServlet</servlet-name>
        <servlet-class>com.example.demo.GetRequestHeaderServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>getRequestHeaderServlet</servlet-name>
        <url-pattern>/getHeader.do</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>LanguageServlet</servlet-name>
        <servlet-class>com.example.demo.LanguageServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>LanguageServlet</servlet-name>
        <url-pattern>/Languages.do</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>RespByteServlet</servlet-name>
        <servlet-class>com.example.demo.RespByteServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>RespByteServlet</servlet-name>
        <url-pattern>/RespByte.do</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>RedirectServlet</servlet-name>
        <servlet-class>com.example.demo.RedirectServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>RedirectServlet</servlet-name>
        <url-pattern>/Redirect.do</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>DownFileServlet</servlet-name>
        <servlet-class>com.example.demo.DownFileServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>DownFileServlet</servlet-name>
        <url-pattern>/Down.do</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>GetBaseInfoServlet</servlet-name>
        <servlet-class>com.example.demo.GetBaseInfoServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>GetBaseInfoServlet</servlet-name>
        <url-pattern>/getBaseInfo.do</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>ContextReadInfoServlet</servlet-name>
        <servlet-class>com.example.demo.ContextReadInfoServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>ContextReadInfoServlet</servlet-name>
        <url-pattern>/Context.do</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>GlobalContainerServlet</servlet-name>
        <servlet-class>com.example.demo.GlobalContainerServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>GlobalContainerServlet</servlet-name>
        <url-pattern>/Global.do</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>GetConfigInfoServlet</servlet-name>
        <servlet-class>com.example.demo.GetConfigInfoServlet</servlet-class>
        <init-param>
            <param-name>key1</param-name>
            <param-value>BJSXT</param-value>
        </init-param>
        <init-param>
            <param-name>key2</param-name>
            <param-value>ITBZ</param-value>
        </init-param>
    </servlet>
    <servlet-mapping>
        <servlet-name>GetConfigInfoServlet</servlet-name>
        <url-pattern>/Config.do</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>CreatCookieSrvlet</servlet-name>
        <servlet-class>com.example.demo.CreatCookieSrvlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>CreatCookieSrvlet</servlet-name>
        <url-pattern>/Cookie.do</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>GetCookieDataServlet</servlet-name>
        <servlet-class>com.example.demo.GetCookieDataServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>GetCookieDataServlet</servlet-name>
        <url-pattern>/GetCookie.do</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>WelcomeServlet</servlet-name>
        <servlet-class>com.example.demo.WelcomeServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>WelcomeServlet</servlet-name>
        <url-pattern>/Welcome.do</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>CreateHttpSessionServlet</servlet-name>
        <servlet-class>com.example.demo.CreateHttpSessionServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>CreateHttpSessionServlet</servlet-name>
        <url-pattern>/CreatSession.do</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>GetHttpSessionDataServlet</servlet-name>
        <servlet-class>com.example.demo.GetHttpSessionDataServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>GetHttpSessionDataServlet</servlet-name>
        <url-pattern>/GetSessionData.do</url-pattern>
    </servlet-mapping>
    <session-config>
        <session-timeout>1</session-timeout>
    </session-config>
    <servlet>
        <servlet-name>WelcomeSessionServlet</servlet-name>
        <servlet-class>com.example.demo.WelcomeSessionServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>WelcomeSessionServlet</servlet-name>
        <url-pattern>/WelcomeSession.do</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>AutoStartServlet</servlet-name>
        <servlet-class>com.example.demo.AutoStartServlet</servlet-class>
        <init-param>
            <param-name>path</param-name>
            <param-value>image</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>AutoStartServlet</servlet-name>
        <url-pattern>/auto.do</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>ThreadSafeServlet</servlet-name>
        <servlet-class>com.example.demo.ThreadSafeServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>ThreadSafeServlet</servlet-name>
        <url-pattern>/Safe.do</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>FileUploadServlet</servlet-name>
        <servlet-class>com.example.demo.FileUploadServlet</servlet-class>
        <multipart-config>
            <file-size-threshold>2000</file-size-threshold>
        </multipart-config>
    </servlet>
    <servlet-mapping>
        <servlet-name>FileUploadServlet</servlet-name>
        <url-pattern>/fileupload.do</url-pattern>
    </servlet-mapping>
</web-app>

package com.example.demo;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.Part;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.UUID;

public class FileUploadServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("utf-8");
        String desc = req.getParameter("desc");
        Part part=req.getPart("file");
//        InputStream inputStream = part.getInputStream();
        String filename= UUID.randomUUID().toString()+part.getSubmittedFileName().substring(part.getSubmittedFileName().lastIndexOf("."));
        ServletContext servletContext = this.getServletContext();
        String realPath = servletContext.getRealPath("image"+filename);
        part.write(realPath);
        PrintWriter out=resp.getWriter();
        out .println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
        out.println("<HTML>");
        out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
        out.println(" <BODY>");
        out.println("上传成功");
        out.println("</BODY>");
        out.println("</HTML>");
        out.flush();
        out.close();
    }
}

老师，这节课也是和上节课一样的问题，成功初始化servlet后，并没有出现value1和value2，访问页面也是404报错，老师能不能帮忙看看哪里出问题了

package com.example.demo;

import jakarta.servlet.ServletConfig;
import jakarta.servlet.ServletException;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

import javax.servlet.annotation.WebInitParam;
import javax.servlet.annotation.WebServlet;
import java.io.IOException;
import java.io.PrintWriter;

@WebServlet(urlPatterns="/initParam.do" ,initParams ={@WebInitParam(name="key1",value="value1"),@WebInitParam(name="key2",value = "value2")} ,loadOnStartup = 1)
public class InitParamServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        ServletConfig servletConfig = this.getServletConfig();
        PrintWriter out=resp.getWriter();
        out .println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
        out.println("<HTML>");
        out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
        out.println(" <BODY>");
        out.println("Value1"+servletConfig.getInitParameter("key1")+"<br/>");
        out.println("Value2"+servletConfig.getInitParameter("key2")+"<br/>");
        out.println("</BODY>");
        out.println("</HTML>");
        out.flush();
        out.close();
    }

    @Override
    public void init() throws ServletException {
        ServletConfig servletConfig = this.getServletConfig();
        System.out.println(servletConfig.getInitParameter("key1"));
        System.out.println(servletConfig.getInitParameter("key2"));
    }
}

我用注解无法获取响应页面，老师能帮忙看看是咋回事吗

package com.example.demo;

import jakarta.servlet.ServletException;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

import javax.servlet.annotation.WebServlet;
import java.io.IOException;
import java.io.PrintWriter;
@WebServlet(urlPatterns = "/ann.do")
public class AnnotationServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        PrintWriter out=resp.getWriter();
        out .println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
        out.println("<HTML>");
        out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
        out.println(" <BODY>");
        out.println("Annotation servlet");
        out.println("</BODY>");
        out.println("</HTML>");
        out.flush();
        out.close();
    }
}

老师，访问index.jsp会调用getSession对象那里还是有疑问，在调用index.jsp时返回Session那块（和我们写的创建session的代码有关吗，还是Tomcat默认的行为，如果是默认的，那这种调用有什么用呀）

1.getCookie会将服务器端给予客户端的所有Cookie对象返回（不同域名下的一并返回）这样理解是对的吗

2.getCookie方法是不是通过ip地址和端口号实现区分不同客户端呀

<context-param>标签有啥用法呀，为啥该方法可以读取 web.xml 文件中<context-param>标签中的配置信息，但是不读取servlet标签信息，目前还不太了解<context-param>的用途

1、在162 web案例_创建查询用户持久层这节课时老师在拼接sql语句时应该给varchar类型的数据添加' '。因为我们         不是使用setString方法添加的数据，而是自己手动添加的，所以需要添加' '，这里老师是不是忘记啦？

2、如上图，因为我们没有在拼接字符串时添加' '，所以此节课中使用varchar类型进行数据查询时就会报错，查询的         sql语句就会拼接成这样子：select * from users where 1=1 and username=admin; 不符合sql语法规范。

3、视频中老师进行查询没有出错是因为查询条件只是使用性别，性别是使用1和0表示的，所以不需要给int类型的数       据添加' '

4、我在本节课实操时出现上述的问题，不知道是我自己写代码的时候落下什么了，还是老师讲课的时候出现了一点失       误，如果是我个人的问题，麻烦老师指出我的问题，

您好老师，在创建表格时，为什么给表名和字段名添加单引号' '呀？

为什么把document放for 循环里面结果只输出一个呢?

为什么我的项目查询和添加数据不成功?添加数据不会跳转到error.jsp也不会跳转到OK.jsp页面.

用老师的项目导入也一样, 上面这个是用老师项目导入后的效果.查询不到数据.

那服务端口号会不会被占用完，占用完应该怎么办呢

fis需要关吗                                                             

这是ie浏览器产生的效果，看不了验证码

这是谷歌浏览器产生的效果，为啥两个差别这么大。而且没有添加验证码登录后内部页面可以正常显示。加了验证码看不了就登录不进去了

tomcat控制台乱码