web一些实验代码——Servlet请求与响应-编程知识

web一些实验代码——Servlet请求与响应

实验4：Servlet请求与响应

1、在页面输入学生学号，从数据库中查询学生信息并显示。

（1）启动MySQL数据库服务，新建数据库，将student.sql文件导入到新建数据库（建立表，并插入3条数据）

（2）新建html页面：

<!DOCTYPE html>
<html lang="en" xmlns="http://www.w3.org/1999/html">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body>
<form action="/weeebbbb_war_exploded/LoginServlet" method="post">用户名：<input type="text" name="username"></br>密码：<input type="password" name="password"></br><input type="submit" value="提交">
</form>
</body>
</html>

（3）新建DbUtil类：

package com.example.weeebbbb;import java.sql.*;public class DbUtil {public static String DRIVER ="com.mysql.jdbc.Driver";//数据库public static final String URL ="jdbc:mysql://localhost:3306/student?useSSL=false";public static final String DBUser = "root";public static final String DBPassword = "123456";public static Connection conn = null;public static Connection getConn(String dbDri,String dbUrl,String username,String pass) {try {Class.forName(DRIVER);conn = DriverManager.getConnection(URL, DBUser, DBPassword);} catch (Exception e) {e.printStackTrace();}return conn;}
}

（4）在web.xml文件中配置数据库连接信息：

    <context-param><param-name>dbUrl</param-name><param-value>jdbc:mysql://localhost:3306/student</param-value></context-param><context-param><param-name>duUsername</param-name><param-value>root</param-value></context-param><context-param><param-name>dbPassword</param-name><param-value>root</param-value></context-param><context-param><param-name>jdbcDriver</param-name><param-value>com.mysql.jdbc.Driver</param-value></context-param>

（5）在pom.xml文件中添加MySQL驱动依赖（需要联网，一定要考虑自己数据库的版本，注意驱动版本和web.xml文件中的jdbcDriver驱动字符串的写法），则项目可不用导入MySQL驱动jar包，

 <dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>5.1.49</version>
</dependency>

（6）新建Servlet，完成获取网页表单提交的学号信息，并从数据库中查询此学号学生的信息，并响应输出：

package com.example.weeebbbb;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 java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;@WebServlet(name ="wek4_queryServlet",value = "/wek4_queryServlet")
public class wek4_queryServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {System.out.println("1111");resp.setContentType("text/html;charset=utf-8");String stuNum=req.getParameter("stuNum");ServletContext context=this.getServletContext();String dbUrl=context.getInitParameter("dbUrl");String dbUsername=context.getInitParameter("dbUsername");String dbPassword=context.getInitParameter("dbPassword");String jdbcDriver=context.getInitParameter("jdbcDriver");Connection connection=DbUtil.getConn(dbUrl,dbUsername,dbPassword,jdbcDriver);String sql="select * from student where stuNum=?";PreparedStatement pst=null;try{pst= connection.prepareStatement(sql);pst.setString(1,stuNum);ResultSet rs=pst.executeQuery();String str="";System.out.println("11111");if(rs.next()){System.out.println("22222");str="这位同学的学号是"+rs.getString("stuNum")+",姓名是："+rs.getString("stuName");}else{str="查无此人";}resp.getWriter().println(str);}catch (SQLException e){e.printStackTrace();}}
}

（7）新建输入信息页面：

<%--Created by IntelliJ IDEA.User: cicDate: 2023/11/8Time: 14:19To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body>
<form action="wek4_queryServlet" method="get">请输入学号：<input type="text" size="20" name="stuNum"><input type="submit" value="查询">
</form></body>
</html>