jsp增删改查代码

JSP（JavaServer Pages）是一种用于创建动态Web内容的技术，它允许开发者在HTML页面中嵌入Java代码。下面是一个简单的JSP增删改查（CRUD）操作的示例代码。

基础概念

JSP：JavaServer Pages，用于创建动态Web内容。
Servlet：Java Servlet是服务器端技术，用于处理客户端请求并生成响应。
数据库连接：使用JDBC（Java Database Connectivity）连接和操作数据库。

示例代码

1. 数据库连接类（DBConnection.java）

import java.sql.*;

public class DBConnection {
    private static final String URL = "jdbc:mysql://localhost:3306/mydatabase";
    private static final String USER = "username";
    private static final String PASSWORD = "password";

    public static Connection getConnection() throws SQLException {
        return DriverManager.getConnection(URL, USER, PASSWORD);
    }
}

2. 创建（Create）

<%@ page import="java.sql.*" %>
<%
    String name = request.getParameter("name");
    String email = request.getParameter("email");

    try (Connection conn = DBConnection.getConnection();
         PreparedStatement pstmt = conn.prepareStatement("INSERT INTO users(name, email) VALUES(?, ?)")) {
        pstmt.setString(1, name);
        pstmt.setString(2, email);
        pstmt.executeUpdate();
        out.println("User added successfully!");
    } catch (SQLException e) {
        out.println("Error: " + e.getMessage());
    }
%>

3. 读取（Read）

<%@ page import="java.sql.*" %>
<%
    try (Connection conn = DBConnection.getConnection();
         Statement stmt = conn.createStatement();
         ResultSet rs = stmt.executeQuery("SELECT * FROM users")) {
        while (rs.next()) {
            out.println("ID: " + rs.getInt("id") + ", Name: " + rs.getString("name") + ", Email: " + rs.getString("email") + "<br>");
        }
    } catch (SQLException e) {
        out.println("Error: " + e.getMessage());
    }
%>

4. 更新（Update）

<%@ page import="java.sql.*" %>
<%
    int id = Integer.parseInt(request.getParameter("id"));
    String name = request.getParameter("name");
    String email = request.getParameter("email");

    try (Connection conn = DBConnection.getConnection();
         PreparedStatement pstmt = conn.prepareStatement("UPDATE users SET name=?, email=? WHERE id=?")) {
        pstmt.setString(1, name);
        pstmt.setString(2, email);
        pstmt.setInt(3, id);
        pstmt.executeUpdate();
        out.println("User updated successfully!");
    } catch (SQLException e) {
        out.println("Error: " + e.getMessage());
    }
%>

5. 删除（Delete）

<%@ page import="java.sql.*" %>
<%
    int id = Integer.parseInt(request.getParameter("id"));

    try (Connection conn = DBConnection.getConnection();
         PreparedStatement pstmt = conn.prepareStatement("DELETE FROM users WHERE id=?")) {
        pstmt.setInt(1, id);
        pstmt.executeUpdate();
        out.println("User deleted successfully!");
    } catch (SQLException e) {
        out.println("Error: " + e.getMessage());
    }
%>