用jsp编写一个宠物增加修改删除代码

好的，以下是一个简单的宠物信息增删改查的JSP代码示例：

首先是添加宠物信息的代码，假设我们有一个Pet表，其中有id、name、age、type和gender等字段：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ page import="java.sql.*" %>

<%
    request.setCharacterEncoding("UTF-8"); // 设置请求编码为UTF-8

    String name = request.getParameter("name"); // 获取表单提交的数据
    String age = request.getParameter("age");
    String type = request.getParameter("type");
    String gender = request.getParameter("gender");

    Connection conn = null;
    PreparedStatement stmt = null;

    try {
        Class.forName("com.mysql.jdbc.Driver"); // 加载MySQL驱动

        // 建立数据库连接
        String url = "jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC";
        String user = "root";
        String password = "123456";
        conn = DriverManager.getConnection(url, user, password);

        // 构造SQL语句
        String sql = "INSERT INTO Pet(name, age, type, gender) VALUES(?, ?, ?, ?)";
        stmt = conn.prepareStatement(sql);

        // 设置参数
        stmt.setString(1, name);
        stmt.setInt(2, Integer.parseInt(age));
        stmt.setString(3, type);
        stmt.setString(4, gender);

        // 执行SQL语句
        int rows = stmt.executeUpdate();

        if (rows > 0) {
            out.print("添加成功！");
        } else {
            out.print("添加失败！");
        }
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        // 关闭数据库连接
        try {
            if (stmt != null) {
                stmt.close();
            }
            if (conn != null) {
                conn.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
%>

然后是修改宠物信息的代码，假设我们要根据id来修改宠物信息：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ page import="java.sql.*" %>

<%
    request.setCharacterEncoding("UTF-8"); // 设置请求编码为UTF-8

    int id = Integer.parseInt(request.getParameter("id")); // 获取表单提交的数据
    String name = request.getParameter("name");
    String age = request.getParameter("age");
    String type = request.getParameter("type");
    String gender = request.getParameter("gender");

    Connection conn = null;
    PreparedStatement stmt = null;

    try {
        Class.forName("com.mysql.jdbc.Driver"); // 加载MySQL驱动

        // 建立数据库连接
        String url = "jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC";
        String user = "root";
        String password = "123456";
        conn = DriverManager.getConnection(url, user, password);

        // 构造SQL语句
        String sql = "UPDATE Pet SET name=?, age=?, type=?, gender=? WHERE id=?";
        stmt = conn.prepareStatement(sql);

        // 设置参数
        stmt.setString(1, name);
        stmt.setInt(2, Integer.parseInt(age));
        stmt.setString(3, type);
        stmt.setString(4, gender);
        stmt.setInt(5, id);

        // 执行SQL语句
        int rows = stmt.executeUpdate();

        if (rows > 0) {
            out.print("修改成功！");
        } else {
            out.print("修改失败！");
        }
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        // 关闭数据库连接
        try {
            if (stmt != null) {
                stmt.close();
            }
            if (conn != null) {
                conn.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
%>

最后是删除宠物信息的代码，同样是根据id来删除：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ page import="java.sql.*" %>

<%
    request.setCharacterEncoding("UTF-8"); // 设置请求编码为UTF-8

    int id = Integer.parseInt(request.getParameter("id")); // 获取表单提交的数据

    Connection conn = null;
    PreparedStatement stmt = null;

    try {
        Class.forName("com.mysql.jdbc.Driver"); // 加载MySQL驱动

        // 建立数据库连接
        String url = "jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC";
        String user = "root";
        String password = "123456";
        conn = DriverManager.getConnection(url, user, password);

        // 构造SQL语句
        String sql = "DELETE FROM Pet WHERE id=?";
        stmt = conn.prepareStatement(sql);

        // 设置参数
        stmt.setInt(1, id);

        // 执行SQL语句
        int rows = stmt.executeUpdate();

        if (rows > 0) {
            out.print("删除成功！");
        } else {
            out.print("删除失败！");
        }
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        // 关闭数据库连接
        try {
            if (stmt != null) {
                stmt.close();
            }
            if (conn != null) {
                conn.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
%>

另外，还需要编写一个查询宠物信息的代码，用于显示宠物列表、编辑宠物信息等功能。具体实现方式可以使用JDBC连接数据库，构造SQL语句查询Pet表中的数据，并将结果以表格的形式显示在页面上。