jsp页面实现增删改查

JSP页面可以通过与后端代码交互来实现增删改查的功能。以下是一个简单的示例：

1. 实现查询功能：

<%@ page import="java.sql.*" %>
<%
    // 连接数据库
    String url = "jdbc:mysql://localhost:3306/mydatabase";
    String username = "root";
    String password = "password";
    Connection conn = DriverManager.getConnection(url, username, password);
    
    // 执行查询语句
    String sql = "SELECT * FROM students";
    Statement stmt = conn.createStatement();
    ResultSet rs = stmt.executeQuery(sql);
    
    // 显示查询结果
    while (rs.next()) {
        out.println("ID: " + rs.getInt("id") + "<br>");
        out.println("Name: " + rs.getString("name") + "<br>");
        out.println("Age: " + rs.getInt("age") + "<br>");
        out.println("<br>");
    }
    
    // 关闭连接
    rs.close();
    stmt.close();
    conn.close();
%>

2. 实现添加功能：

<%@ page import="java.sql.*" %>
<%
    // 获取表单数据
    String name = request.getParameter("name");
    int age = Integer.parseInt(request.getParameter("age"));
    
    // 连接数据库
    String url = "jdbc:mysql://localhost:3306/mydatabase";
    String username = "root";
    String password = "password";
    Connection conn = DriverManager.getConnection(url, username, password);
    
    // 执行插入语句
    String sql = "INSERT INTO students (name, age) VALUES (?, ?)";
    PreparedStatement pstmt = conn.prepareStatement(sql);
    pstmt.setString(1, name);
    pstmt.setInt(2, age);
    pstmt.executeUpdate();
    
    // 关闭连接
    pstmt.close();
    conn.close();
%>

3. 实现修改功能：

<%@ page import="java.sql.*" %>
<%
    // 获取表单数据
    int id = Integer.parseInt(request.getParameter("id"));
    String name = request.getParameter("name");
    int age = Integer.parseInt(request.getParameter("age"));
    
    // 连接数据库
    String url = "jdbc:mysql://localhost:3306/mydatabase";
    String username = "root";
    String password = "password";
    Connection conn = DriverManager.getConnection(url, username, password);
    
    // 执行更新语句
    String sql = "UPDATE students SET name = ?, age = ? WHERE id = ?";
    PreparedStatement pstmt = conn.prepareStatement(sql);
    pstmt.setString(1, name);
    pstmt.setInt(2, age);
    pstmt.setInt(3, id);
    pstmt.executeUpdate();
    
    // 关闭连接
    pstmt.close();
    conn.close();
%>

4. 实现删除功能：

<%@ page import="java.sql.*" %>
<%
    // 获取表单数据
    int id = Integer.parseInt(request.getParameter("id"));
    
    // 连接数据库
    String url = "jdbc:mysql://localhost:3306/mydatabase";
    String username = "root";
    String password = "password";
    Connection conn = DriverManager.getConnection(url, username, password);
    
    // 执行删除语句
    String sql = "DELETE FROM students WHERE id = ?";
    PreparedStatement pstmt = conn.prepareStatement(sql);
    pstmt.setInt(1, id);
    pstmt.executeUpdate();
    
    // 关闭连接
    pstmt.close();
    conn.close();
%>