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JavaWeb通过Web查询数据库内容：
- 数据库：
-
- 自行建库建表，主键 id
- 后端：
-
- 新建项目模块
- 选择模块，添加依赖
- 创建配置文件：
-
- db.properties
- Java类： query查询
- 前端：
-
- Web添加
- 创建query.html首页
- 创建Artifacts
- 创建配置Tomcat服务器：
-
- 添加Artifacts
- 配置web.xml文件
- 运行Tomcat服务器
- 补充：JDBC增删改查数据库(点击可跳转)
数据库：
自行建库建表，主键 id
后端：
新建项目模块
选择模块，添加依赖
创建配置文件：
db.properties
driver=com.mysql.cj.jdbc.Driver
user=root
url=jdbc:mysql://127.0.0.1:3306/csdn
password=ROOT
Java类： query查询
package com.swc;import jakarta.servlet.ServletException;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;import java.io.IOException;
import java.io.PrintWriter;
import java.sql.*;
import java.util.ResourceBundle;public class query extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// 设置 请求和相应的 编码格式request.setCharacterEncoding("utf-8");response.setCharacterEncoding("utf-8");response.setContentType("text/html");PrintWriter out = response.getWriter();
// 连接数据库ResourceBundle bundle = ResourceBundle.getBundle("com/swc/resources/db");String driver = bundle.getString("driver");String url = bundle.getString("url");String user = bundle.getString("user");String password = bundle.getString("password");
// 放大作用于Connection con = null;Statement st = null;ResultSet rs = null;try {Class.forName(driver);con = DriverManager.getConnection(url, user, password);con.setAutoCommit(false);st = con.createStatement();String sql = "select * from pfour_webquerymysql";rs = st.executeQuery(sql);// 遍历结果集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("</head>");out.print("<body>");out.print(" ");out.print(" <table border='2px' width='400px'>");out.print(" <tr>");out.print(" <td>姓名</td>");out.print(" <td>性别</td>");out.print(" </tr>");while (rs.next()) {String name = rs.getString("name");String sex = rs.getString("sex");out.print(" <tr>");out.print(" <td>" + name + "</td>");out.print(" <td>" + sex + "</td>");out.print(" </tr>");}out.print("");out.print(" </table>");out.print("</body>");out.print("</html>");con.commit();} catch (ClassNotFoundException | SQLException e) {if (con != null) {try {con.rollback();} catch (SQLException throwables) {throwables.printStackTrace();}}e.printStackTrace();} finally {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();}}}}
}
前端：
Web添加
创建query.html首页
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title><style>div {font-size: 48px;color: red;}a {text-decoration: none;}</style>
</head>
<body>
<!-- 显示页面 -->
<h1>信息系统</h1>
<a href="/pfour_webquerymysql/query">查询来自数据库的成员</a></body>
</html>
创建Artifacts
创建配置Tomcat服务器：
添加Artifacts
- 下划线 _ 后删掉，留下项目名
配置web.xml文件
-
servlet-name 的内容要相同
-
<?xml version="1.0" encoding="UTF-8"?>
query.html
pfour_webquerymysql
com.swc.query
pfour_webquerymysql
/query
运行Tomcat服务器
- 跳转到浏览器
- 点击——>查询来自数据库的成员
- 即可