Java（JavaWeb02）_zach sun-优快云博客

本文链接：https://blog.youkuaiyun.com/Zachsj/article/details/124932282

Java（JavaWeb02）

参考视频：8. HelloServlet（狂神）

6. Servlet

6.1 Servlet简介

servlet是sun公司开发动态web的一门技术
sun在这些api中提供一个接口叫做：servlet，如果你想开发一个servlet程序，只需要完成两个小步骤：
- 编写一个类，实现servlet接口
- 把开发好的java类部署到web服务器中
把实现了servlet接口的java程序，叫做servlet

6.2 HelloServlet

对于Servlet接口，sun公司有两个默认的实现类：HttpServlet、GenericServlet

构建一个普通的Maven项目，并删掉src目录，以后在这个项目里建立Module。这个空的工程就是Maven的主工程。

pom.xml

<?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>
	
	<groupId>com.zach</groupId>
	<artifactId>javaweb-02-servlet</artifactId>
	<version>1.0-SNAPSHOT</version>
	
	<properties>
		<maven.compiler.source>8</maven.compiler.source>
		<maven.compiler.target>8</maven.compiler.target>
	</properties>

	<dependencies>
		<!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->
		<dependency>
			<groupId>javax.servlet</groupId>
			<artifactId>javax.servlet-api</artifactId>
			<version>4.0.1</version>
			<scope>provided</scope>
		</dependency>
		<!-- https://mvnrepository.com/artifact/javax.servlet.jsp/javax.servlet.jsp-api -->
		<dependency>
			<groupId>javax.servlet.jsp</groupId>
			<artifactId>javax.servlet.jsp-api</artifactId>
			<version>2.3.3</version>
			<scope>provided</scope>
		</dependency>
	</dependencies>
	
</project>

关于Maven父子工程的理解：

父项目的pox.xml中会有

	<modules>
		<module>servlet-01</module>
	</modules>

子项目的pox.xml中会有

	<parent>
		<groupId>com.zach</groupId>
		<artifactId>javaweb-02-servlet</artifactId>
		<version>1.0-SNAPSHOT</version>
	</parent>

父项目中的jar包，子项目可以直接使用。

son extends father

关于parent标签问题：

问题1： 没有自动生成parent标签，是因为配置与版本等问题。
解决方法：在maven文件夹下的conf下的settings.xml的profiles标签里添加下面配置：

	<profile>
        <id>jdk-1.8</id>
		<activation>
			<activeByDefault>true</activeByDefault>
			<jdk>1.8</jdk>
		</activation>

		<properties>
			<maven.compiler.source>1.8</maven.compiler.source>
			<maven.compiler.target>1.8</maven.compiler.target>
			<maven.compiler.compilerVersion>1.8</maven.compiler.compilerVersion>
        </properties>
    </profile>

问题2： 自动生成parent标签后，几秒就消失了。原因是被“替换中”出现了问题，属于IDEA软件的bug范畴。更新版本可修复。如果因为某种原因无法使用新版本，只能手动操作。
官方问答：https://intellij-support.jetbrains.com/hc/en-us/community/posts/4406369605266/comments/4406387494162
解决方法（手动）：改成如下即可
关于问题2的截图展示：
刚开始生成，有parent标签
生成完全结束后，没有parent标签

Maven环境优化

修改web.xml为最新的

<?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="true">
	
</web-app>

将maven的结构搭建完整

编写一个Servlet程序

编写一个普通类，实现Servlet接口，这里我们直接继承HttpServlet

package com.zach.servlet;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

public class HelloServlet extends HttpServlet {
    
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//        super.doGet(req, resp);
//        ServletOutputStream outputStream = resp.getOutputStream();
        PrintWriter writer = resp.getWriter();// 响应流
        writer.println("Hello,Servlet!");
    }
    
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//        super.doPost(req, resp);
        doGet(req, resp);
    }
}

编写Servlet的映射

为什么需要映射：我们写的是Java程序，但是要通过浏览器访问，而浏览器需要连接web服务器，所以我们需要在web服务中注册我们写的Servlet，还需要给它一个浏览器能够访问的路径。
在web.xml中增加配置如下：

	<!--注册Servlet-->
	<servlet>
		<servlet-name>hello</servlet-name>
		<servlet-class>com.zach.servlet.HelloServlet</servlet-class>
	</servlet>
	
	<!--Servlet的请求路径-->
	<servlet-mapping>
		<servlet-name>hello</servlet-name>
		<url-pattern>/hello</url-pattern>
	</servlet-mapping>

配置Tomcat

注意配置项目发布的路径： /s1

启动测试

Output乱码问题：-Dfile.encoding=utf-8

6.3 Servlet原理

Servlet是由Web服务器调用，web服务器在收到浏览器请求之后，会：

6.4 Mapping问题

一个Servlet可以指定一个映射路径

	<servlet-mapping>
		<servlet-name>hello</servlet-name>
		<url-pattern>/hello</url-pattern>
	</servlet-mapping>

一个Servlet可以指定多个映射路径

	<servlet-mapping>
		<servlet-name>hello</servlet-name>
		<url-pattern>/hello</url-pattern>
	</servlet-mapping>
	<servlet-mapping>
		<servlet-name>hello</servlet-name>
		<url-pattern>/hello2</url-pattern>
	</servlet-mapping>
	<servlet-mapping>
		<servlet-name>hello</servlet-name>
		<url-pattern>/hello3</url-pattern>
	</servlet-mapping>

一个Servlet可以指定通用映射路径

	<servlet-mapping>
		<servlet-name>hello</servlet-name>
		<url-pattern>/hello/*</url-pattern>
	</servlet-mapping>

默认请求路径

	<servlet-mapping>
		<servlet-name>hello</servlet-name>
		<url-pattern>/*</url-pattern>
	</servlet-mapping>

指定一些后缀或者前缀等

	<!--可以自定义后缀实现请求映射
	注意：*前面不能加项目映射的路径以及/-->
	<servlet-mapping>
		<servlet-name>hello</servlet-name>
		<url-pattern>*.sj</url-pattern>
	</servlet-mapping>

优先级问题：

指定了固有的映射路径优先级最高，如果找不到才会走默认的处理请求。

	<!--404-->
	<servlet>
		<servlet-name>error</servlet-name>
		<servlet-class>com.zach.servlet.ErrorServlet</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>error</servlet-name>
		<url-pattern>/*</url-pattern>
	</servlet-mapping>

6.5 ServletContext

web容器在启动的时候，它会为每个web程序都创建一个对应的ServletContext对象，它代表了当前的web应用。

6.5.1 共享数据：

我在这个servlet中保存的数据，可以在另外一个servlet中拿到。

package com.zach.servlet;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class HelloServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    
//        this.getInitParameter();//初始化参数
//        this.getServletConfig();//Servlet配置
//        this.getServletContext();//Servlet上下文
        ServletContext context = this.getServletContext();
        
        String username = "柴客";//数据
        context.setAttribute("username",username);//将一个数据保存在了ServletContext中
        
    }
}

package com.zach.servlet;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class GetServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        ServletContext context = this.getServletContext();
    
        String username = (String) context.getAttribute("username");
        
        resp.setContentType("text/html");
        resp.setCharacterEncoding("utf-8");
        resp.getWriter().println("你的名字："+username);
    }
    
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

测试访问结果：
- 进入HelloServlet前，先进入GetServlet：你的名字：null
- 进入HelloServlet后，再进入GetServlet：你的名字：柴客

6.5.2 获取初始化参数

web.xml

	<!--配置一些web应用初始化参数-->
	<context-param>
		<param-name>url</param-name>
		<param-value>jdbc:mysql://localhost:3306/mybatis</param-value>
	</context-param>

ServletDemo03

package com.zach.servlet;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class ServletDemo03 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        ServletContext context = this.getServletContext();
        String url = context.getInitParameter("url");
        resp.getWriter().println(url);
    }
    
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

6.5.3 请求转发

package com.zach.servlet;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class ServletDemo04 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        ServletContext context = this.getServletContext();
        System.out.println("进入了ServletDemo04");
//        RequestDispatcher requestDispatcher = context.getRequestDispatcher("/gp");//转发的请求路径
//        requestDispatcher.forward(req,resp);//调用forward实现请求转发。
        context.getRequestDispatcher("/gp").forward(req,resp);
    }
    
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

在这里插入图片描述

6.5.4 读取资源文件

Properties
- 在java目录下新建properties
- 在resources目录下新建properties
发现：都被打包到了同一个路径下：classes，我们称为classpath
如果打包后target里没有，在pom.xml添加以下配置。

	<!--在build中配置resources,来防止我们资源导出失败的问题-->
	<build>
		<resources>
			<resource>
				<directory>src/main/resources</directory>
				<includes>
					<include>**/*.properties</include>
					<include>**/*.xml</include>
				</includes>
				<filtering>false</filtering>
			</resource>
			<resource>
				<directory>src/main/java</directory>
				<includes>
					<include>**/*.properties</include>
					<include>**/*.xml</include>
				</includes>
				<filtering>false</filtering>
			</resource>
		</resources>
	</build>

思路：需要一个文件流！

username=rootroot
password=123456123456

package com.zach.servlet;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

public class ServletDemo05 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    
        InputStream is = this.getServletContext().getResourceAsStream("/WEB-INF/classes/com/zach/servlet/aa.properties");
    
        Properties prop = new Properties();
        prop.load(is);
        String userName = prop.getProperty("username");
        String passWord = prop.getProperty("password");
        
        resp.getWriter().println(userName+"\n"+passWord);
        
    }
    
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

访问测试即可。

6.6 HttpServletResponse

响应
web服务器接收到客户端的http请求，针对这个请求，分别创建一个代表请求的HttpServletRequest对象，一个代表响应的HttpServletResponse
- 如果要获取客户端请求过来的参数：找HttpServletRequest
- 如果要给客户端响应一些信息：找HttpServletResponse

6.6.1 简单分类

负责向浏览器发送数据的方法

       public ServletOutputStream getOutputStream() throws IOException;
       public PrintWriter getWriter() throws IOException;

负责向浏览器发送响应头的方法

   	public void setCharacterEncoding(String charset);

    public void setContentLength(int len);

    public void setContentLengthLong(long len);

    public void setContentType(String type);

    public void setDateHeader(String name, long date);

    public void addDateHeader(String name, long date);

    public void setHeader(String name, String value);

    public void addHeader(String name, String value);

    public void setIntHeader(String name, int value);

    public void addIntHeader(String name, int value);

响应的状态码（常见）

      	/**
        * Status code (200) indicating the request succeeded normally.
        */
       public static final int SC_OK = 200;
       /**
        * Status code (302) indicating that the resource has temporarily
        * moved to another location, but that future references should
        * still use the original URI to access the resource.
        *
        * This definition is being retained for backwards compatibility.
        * SC_FOUND is now the preferred definition.
        */
       public static final int SC_MOVED_TEMPORARILY = 302;
       /**
        * Status code (404) indicating that the requested resource is not
        * available.
        */
       public static final int SC_NOT_FOUND = 404;
       /**
        * Status code (500) indicating an error inside the HTTP server
        * which prevented it from fulfilling the request.
        */
       public static final int SC_INTERNAL_SERVER_ERROR = 500;
       /**
        * Status code (502) indicating that the HTTP server received an
        * invalid response from a server it consulted when acting as a
        * proxy or gateway.
        */
       public static final int SC_BAD_GATEWAY = 502;

6.6.2 下载文件

向浏览器输出消息（前面一直在讲，此处省略）
下载文件
1. 获取下载文件的路径
2. 下载的文件名是啥？
3. 设置想办法让浏览器能都支持我们下载的东西。文件名是中文的时候，可以设置URLEncoder.encode(fileName, "UTF-8")，否则有可能乱码
4. 获取下载文件的输入流
5. 创建缓冲区
6. 获取OutputStream对象
7. 将FileOutputStream流写入到buffer缓冲区，使用OutputStream将缓冲区中的数据输出到客户端！

FileServlet

package com.zach.servlet;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.FileInputStream;
import java.io.IOException;
import java.net.URLEncoder;

// 下载文件
public class FileServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // 1. 获取下载文件的路径
        String realPath = "C:\\Users\\Administrator\\IdeaProjects\\JavaWeb\\javaweb-02-servlet\\response\\src\\main\\resources\\柴客.png";
        System.out.println("要下载的文件的路径："+realPath);
        // 2. 下载的文件名是啥？
        String fileName = realPath.substring(realPath.lastIndexOf("\\") + 1);
        // 3. 设置想办法让浏览器能都支持我们下载的东西。文件名是中文的时候，可以设置`URLEncoder.encode(fileName, "UTF-8")`，否则有可能乱码
        resp.setHeader("Content-Disposition","attachment;filename="+ URLEncoder.encode(fileName, "UTF-8"));
        // 4. 获取下载文件的输入流
        FileInputStream in = new FileInputStream(realPath);
        // 5. 创建缓冲区
        int len = 0;
        byte[] buffer = new byte[1024];
        // 6. 获取OutputStream对象
        ServletOutputStream out = resp.getOutputStream();
        // 7. 将FileOutputStream流写入到buffer缓冲区,使用OutputStream将缓冲区中的数据输出到客户端！
        while ((len=in.read(buffer))>0){
            out.write(buffer,0,len);
        }
        
        in.close();
        out.close();
    }
    
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

6.6.3 验证码功能

验证码怎么来的？
- 前端实现
- 后端实现，需要用到java图片类，生成一个图片
ImageServlet

package com.zach.servlet;

import sun.awt.image.BufferedImageDevice;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

public class ImageServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        
        //如何让浏览器3秒刷新一次（自动）
        resp.setHeader("refresh","3");
        
        //在内存中创建一个图片
        BufferedImage bufferedImage = new BufferedImage(80, 20, BufferedImage.TYPE_INT_RGB);
        //得到图片
        Graphics2D graphics = (Graphics2D) bufferedImage.getGraphics();//2D的笔
        //设置图片的背景颜色
        graphics.setColor(Color.white);
        graphics.fillRect(0,0,80,20);
        //给图片写数据
        graphics.setColor(Color.BLUE);
        graphics.setFont(new Font(null,Font.BOLD,20));
        graphics.drawString(makeNum(),0,20);
        
        //告诉浏览器，这个请求用图片的方式打开
        resp.setContentType("image/jpeg");
        //网站存在缓存，不让浏览器缓存
        resp.setDateHeader("expires",-1);
        resp.setHeader("Cache-Control","no-cache");
        resp.setHeader("Pragma","no-cache");
        
        //把图片写给浏览器
        boolean write = ImageIO.write(bufferedImage, "jpg", resp.getOutputStream());
        
    
    }
    
    //生成随机数
    private String makeNum(){
        Random random = new Random();
        String num = random.nextInt(9999999)+"";
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < 7 - num.length(); i++) {
            sb.append("0");
        }
        num = sb.toString() + num;
        return num;
    }
    
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

6.6.4 实现重定向

在这里插入图片描述

一个web资源（B）收到客户端（A）请求后，他（B）会通知客户端（A）去访问另外一个web资源（C），这个过程叫重定向。
常见场景：
- 用户登录

void sendRedirect(String location) throws IOException;

RedirectServlet（测试）

package com.zach.servlet;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class RedirectServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        /*
        resp.setHeader("Location","/response_war/img");
        resp.setStatus(302);
         */
        resp.sendRedirect("/response_war/img");//重定向
    }
    
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

面试题：请你聊聊重定向和转发的区别？
- 相同点：
  - 页面都会实现跳转
- 不同点：
  - 请求转发的时候，url地址栏不会变
  - 重定向的时候，url地址栏会变

模拟登陆：
index.jsp

<html>
<body>
<h2>Hello World!</h2>

<%--这里提交的路径，需要寻找到项目的路径--%>
<%--${pageContext.request.contextPath}代表当前的项目--%>
<%--jsp代码里面加上这些话<%@ page contentType="text/html; charset=UTF-8"%>--%>
<%@ page contentType="text/html; charset=UTF-8"%>

<form action="${pageContext.request.contextPath}/login" method="get">
    用户名：<input type="text" name="username"> <br>
    密&emsp;码：<input type="password" name="password"> <br>
    <input type="submit">
</form>



</body>
</html>

success.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>

<h1>Success!!!</h1>

</body>
</html>

RequestTest

package com.zach.servlet;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class RequestTest extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //处理请求
        String username = req.getParameter("username");//从请求里面 获取参数
        String password = req.getParameter("password");//从请求里面 获取参数
    
        System.out.println("username: "+username+"\npassword: "+password);
        
        // 重定向时注意：路径问题，可能导致404
        resp.sendRedirect("/response_war/success.jsp");
    }
    
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

6.7 HttpServletRequest

请求
HttpServletRequest代表客户端的请求，用户通过http协议访问服务器，HTTP请求中的所有信息会被封装到HttpServletRequest中，通过HttpServletRequest这个方法，可以获取客户端的所有信息。

获取（前端传递的）参数，请求转发：
LoginServlet

package com.zach.servlet;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Arrays;

public class LoginServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("utf-8");
        resp.setCharacterEncoding("utf-8");
        
        String username = req.getParameter("username");
        String password = req.getParameter("password");
        String[] hobbies = req.getParameterValues("hobbies");
        System.out.println("=========================");
        //后台接收，中文乱码问题
        System.out.println(username);
        System.out.println(password);
        System.out.println(Arrays.toString(hobbies));
        System.out.println("=========================");
        
        //通过请求转发
        req.getRequestDispatcher("/success.jsp").forward(req,resp);
        
    }
    
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

index.jsp

<body>
<h1>登录</h1>
<div>
    <%--这里的表单表示的意思：以post方式提交表单，提交到我们的login请求--%>
    <form action="${pageContext.request.contextPath}/login" method="post">
        用户名：<input type="text" name="username"> <br>
        密&emsp;码：<input type="password" name="password"> <br>
        爱好：
        <input type="checkbox" name="hobbies" value="女孩">女孩
        <input type="checkbox" name="hobbies" value="代码">代码
        <input type="checkbox" name="hobbies" value="唱歌">唱歌
        <input type="checkbox" name="hobbies" value="跳舞">跳舞
        <input type="checkbox" name="hobbies" value="Rap">Rap
        <input type="checkbox" name="hobbies" value="篮球">篮球

        <br>
        <input type="submit">
    </form>
</div>
</body>