文章目录
- 前端准备
- MySQL数据库
- 封装JDBC 连接工具类 DBUtil
- 查寻学生
前端准备
结构
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title>
</head>
<body><a href="./list.html">系统启动</a>
</body>
</html>
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title><!-- 内嵌式 引入 CSS --><style>h1{text-align: center;}/* table 是具有块级属性，所以居住 margin */table{margin: 0 auto;}td{text-align: center;/* 居住 td 中的 文字 */}</style>
</head>
<body><h1>学生信息</h1><table border="1px" width="500px"><tr><td width="120px">姓名</td><td width="120px">学号</td><td width="180px">专业</td><td width="200px">操作</td></tr><tr><td>小明</td><td>1001</td><td>计算机应用技术</td><td width="200px"><a href="./add.html">新增</a><a href="./modify.html">详情</a><a href="javascript:void(0)" onclick="window.confirm('确认删除吗？')" >删除</a></td></tr></table></body>
</html>
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title>
</head>
<body><h1>更新学生信息</h1><form action=""><!-- 原来的信息是来自于数据库的 -->姓名（原来）: <input type="text"><br>学号（原来）: <input type="text"> <br>专业（原来）: <input type="text"><br><!-- 改完后的信息，需要交到 服务器 name -->姓名:<input type="text" name="username"><br>学号:<input type="text" name="stuid" ><br>专业:<input type="text" name="zhuanye"><br><br><input type="submit" value="确认修改" ></form>
</body>
</html>
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title>
</head>
<body><h1>添加学生信息</h1><form action=""><!-- 改完后的信息，需要交到 服务器 name -->姓名:<input type="text" name="username"><br>学号:<input type="text" name="stuid" ><br>专业:<input type="text" name="zhuanye"><br><br><input type="submit" value="确认新增" ></form>
</body>
</html>
MySQL数据库
封装JDBC 连接工具类 DBUtil
package resources;import java.sql.*;
import java.util.ResourceBundle;//
public class DBUtil {private static ResourceBundle bundle = ResourceBundle.getBundle("resources\\db");private static String driver = bundle.getString("driver");private static String url = bundle.getString("url");private static String user = bundle.getString("user");private static String password = bundle.getString("password");
// 驱动注册static{try {Class.forName(driver);
// 本质上： 在 进行类加载的时候，给我把 com.mysql.cj.jdbc.Driver
// com.mysql.cj.jdbc. 下面的 Driver这类 com.mysql.cj.jdbc.Driver . class 加载到
// 方法区内存中（元空间）} catch (ClassNotFoundException e) {e.printStackTrace();}}
// 方法的设计者角度 设计连接对象的静态方法public static Connection getConnection() throws SQLException {Connection connection = DriverManager.getConnection(url, user, password);
// 此处的异常不处理，抛出去，谁调用我，谁来处理异常return connection;}
// 设计关闭流的静态方法 方法设计者public static void close(ResultSet rs, Statement st,Connection con){
// Statement 是 PreparedStatement ps 的父接口
// 调用者 用 Statement PreparedStatement 都支持
// 若第二个参数为 PreparedStatement ps 那么调用者 用 Statement 时会报错，或者要强制类型转换if (rs != null) {try {rs.close();} catch (SQLException throwables) {throwables.printStackTrace();}}if (st != null) {try {st.close();} catch (SQLException throwables) {throwables.printStackTrace();}}if (con != null) {try {con.close();} catch (SQLException throwables) {throwables.printStackTrace();}}}}查寻学生
package com.yanyu;import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import resources.DBUtil;import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;@WebServlet("/list")
public class List extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {request.setCharacterEncoding("utf-8");response.setCharacterEncoding("utf-8");
// 响应的类型response.setContentType("text/html");PrintWriter out = response.getWriter();Connection con = null;Statement st = null;ResultSet rs = null;//查询结果集对象try {con = DBUtil.getConnection();con.setAutoCommit(false);String sql = "select * from student";st = con.createStatement();rs = st.executeQuery(sql);out.print(" <!DOCTYPE html>");out.print("<html lang='en'>");out.print("<head>");out.print(" <meta charset='UTF-8'>");out.print(" <meta name='viewport' content='width=device-width, initial-scale=1.0'>");out.print(" <title>Document</title>");out.print(" <!-- 内嵌式 引入 CSS -->");out.print(" <style>");out.print(" h1{");out.print(" text-align: center;");out.print(" }");out.print(" /* table 是具有块级属性，所以居住 margin */");out.print(" table{");out.print(" margin: 0 auto;");out.print(" }");out.print(" td{");out.print(" text-align: center;");out.print(" /* 居住 td 中的 文字 */");out.print(" }");out.print(" </style>");out.print("</head>");out.print("<body>");out.print(" <h1>学生信息</h1>");out.print(" <table border='1px' width='500px'>");out.print(" <tr>");out.print(" <td width='120px'>学号</td>");out.print(" <td width='180px'>专业</td>");out.print(" <td width='200px'>操作</td>");out.print(" </tr>");while (rs.next()){String name = rs.getString("name");String stuid = rs.getString("stuid");String zhuanye = rs.getString("zhuanye");out.print(" <tr>");out.print(" <td>"+name+"</td>");out.print(" <td>"+stuid+"</td>");out.print(" <td>"+zhuanye+"</td>");out.print(" <td width='200px'>");out.print(" <a href='./add.html'>新增</a>");out.print(" <a href='./modify.html'>详情</a>");out.print(" <a href='javascript:void(0)' οnclick='window.confirm('确认删除吗？')' >删除</a>");out.print(" </td>");out.print(" </tr>");}out.print(" </table>");out.print("</body>");
out.print("</html>");
out.print(" ");con.commit();} catch (SQLException throwables) {
// 回滚事务if (con != null) {try {con.rollback();} catch (SQLException e) {e.printStackTrace();}}throwables.printStackTrace();}}
}
