结果演示

1. 添加

2.删除

3.修改

源代码：

实体类

package com.biienu.entity;

public class User {
    private String id;
    private String name;

    @Override
    public String toString() {
        return "User{" +
                "id='" + id + '\'' +
                ", name='" + name + '\'' +
                '}';
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public User(String id, String name) {
        this.id = id;
        this.name = name;
    }

    public User() {

    }
}

jdbc工具类

package com.biienu.utils;

import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;

public class JdbcUtil {
    static {
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

    public static Connection getConnection() throws SQLException, IOException {
        Properties p = new Properties();
        p.load(Thread.currentThread().getContextClassLoader().getResourceAsStream("db.properties"));
        String url = p.getProperty("url");
        String user = p.getProperty("user");
        String password = p.getProperty("password");
        Connection conn = DriverManager.getConnection(url,user,password);
        return conn;
    }
}

index.jsp

<%@ page import="com.biienu.utils.JdbcUtil" %>
<%@ page import="java.sql.Connection" %>
<%@ page import="java.sql.PreparedStatement" %>
<%@ page import="java.sql.Statement" %>
<%@ page import="java.sql.ResultSet" %>
<%@ page import="com.biienu.entity.User" %>
<%@ page import="java.util.ArrayList" %>
<%@ page import="java.util.List" %><%--

--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>用户信息</title>
</head>
<body>
    <%
        Connection connection = JdbcUtil.getConnection();
        Statement statement = connection.createStatement();
        String sql = "select id, name from t_user";
        ResultSet resultSet = statement.executeQuery(sql);
        List<User> list = new ArrayList<>();
        while(resultSet.next()){
            String id = resultSet.getString("id");
            String name = resultSet.getString("name");
            User u = new User(id, name);
            list.add(u);
        }
    %>
    <table>
        <tr><th>用户id</th><th>用户姓名</th><th class="text-align" colspan="2">操作</th></tr>
        <%
            for(User u: list){
        %>
            <tr>
                <td><%=u.getId()%></td>
                <td><%=u.getName()%></td>
                <td><a href="delete.jsp?id=<%=u.getId()%>">删除</a></td>
                <td><a href="updateForm.jsp?id=<%=u.getId()%>&name=<%=u.getName()%>">修改</a></td>
            </tr>
        <%
            }
        %>
        <tr><td class="text-align" colspan="4"><a href="addForm.jsp">添加用户</a></td></tr>
    </table>
</body>
<script>

</script>

<style>
    .text-align{
        text-align: center
    }
    table{
        width: auto;
        height: 100px;
        margin-left: 30%;
    }
    table,tr,td,th{
        border: 1px solid gray;
    }
</style>
</html>

add.jsp

<%@ page import="java.sql.Connection" %>
<%@ page import="java.sql.Statement" %>
<%@ page import="com.biienu.utils.JdbcUtil" %>
<%@ page import="java.sql.PreparedStatement" %>
<%@ page import="java.io.PrintWriter" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>添加用户</title>
</head>
<body>
    <%
        Connection connection = JdbcUtil.getConnection();
        String sql = "insert into t_user values(?,?)";
        PreparedStatement statement = connection.prepareStatement(sql);

        String userid = (String) request.getParameter("userid");
        String username = (String) request.getParameter("username");
        statement.setString(1, userid);
        statement.setString(2, username);

        int i = statement.executeUpdate();
        if(i > 0){
            response.sendRedirect("/myweb");
        } else {
            response.setContentType("text/html");
            PrintWriter pw = response.getWriter();
            pw.print("<h1>插入失败</h1>");
            pw.flush();
        }
    %>
</body>
</html>

addForm.jsp

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

<form name="upadd" action="add.jsp" method="get">

    <table>
        <tr><td>用户姓名</td><td><input name="username" type="text" /></td></tr>
        <tr><td colspan="2"><input type="submit"  value="提交"></td></tr>
    </table>
</form>
</body>
</html>

delete.jsp

<%@ page import="java.sql.Connection" %>
<%@ page import="com.biienu.utils.JdbcUtil" %>
<%@ page import="java.sql.Statement" %>
<%@ page import="java.sql.PreparedStatement" %>
<%@ page import="java.io.PrintWriter" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <%

        Connection connection = JdbcUtil.getConnection();
        String sql = "delete from t_user where id=?";
        PreparedStatement ps = connection.prepareStatement(sql);
        String id = request.getParameter("id");
        ps.setString(1,id);
        int i = ps.executeUpdate();
        if(i > 0){
            response.sendRedirect("/myweb");
        } else {
            response.setContentType("text/html");
            PrintWriter pw = response.getWriter();
            pw.print("<h1>删除失败</h1>");
            pw.flush();
        }
    %>
</body>
</html>

update.jsp

<%@ page import="java.sql.Connection" %>
<%@ page import="com.biienu.utils.JdbcUtil" %>
<%@ page import="java.sql.PreparedStatement" %>
<%@ page import="java.io.PrintWriter" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>修改</title>
</head>
<body>
<%
    Connection connection = JdbcUtil.getConnection();
    String sql = "update t_user set name=?";
    PreparedStatement ps = connection.prepareStatement(sql);
    String name = request.getParameter("username");
    ps.setString(1,name);
    int i = ps.executeUpdate();
    if(i > 0){
        response.sendRedirect("/myweb");
    } else {
        response.setContentType("text/html");
        PrintWriter pw = response.getWriter();
        pw.print("<h1>修改失败</h1>");
        pw.flush();
    }
%>
</body>
</html>

updateForm.jsp

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

<form action="update.jsp" method="get">

    <table>
        <tr><td>用户姓名</td><td><input name="username" type="text" value="<%=request.getParameter("name")%>"/></td></tr>
        <tr><td colspan="2"><input type="submit"  value="确认修改"></td></tr>
    </table>
</form>
</body>
</html>

数据表

| t_user | CREATE TABLE `t_user` (
  `id` int NOT NULL AUTO_INCREMENT,
  `name` varchar(10) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=22 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci |

input type=“submit” value=“确认修改”>

```

数据表

| t_user | CREATE TABLE `t_user` (
  `id` int NOT NULL AUTO_INCREMENT,
  `name` varchar(10) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=22 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci |