jsp实现评论与回复源码

JSP（JavaServer Pages）是一种用于创建动态Web内容的技术，它允许开发者将Java代码嵌入到HTML页面中，从而实现动态内容的生成。下面是一个简单的JSP实现评论与回复功能的源码示例：

1. 数据库设计

首先，我们需要设计一个简单的数据库表来存储评论和回复信息。假设我们有一个名为comments的表，结构如下：

CREATE TABLE comments (
    id INT AUTO_INCREMENT PRIMARY KEY,
    content TEXT NOT NULL,
    user_id INT NOT NULL,
    parent_id INT DEFAULT NULL, -- NULL表示这是顶级评论，非NULL表示这是回复
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

2. JSP页面

创建一个JSP页面来显示评论和回复。

<%@ page import="java.sql.*" %>
<%@ page import="java.util.*" %>
<html>
<head>
    <title>评论与回复</title>
</head>
<body>
    <h1>评论与回复</h1>
    <form action="submit_comment.jsp" method="post">
        <textarea name="content" required></textarea><br>
        <input type="hidden" name="parent_id" value="0">
        <input type="submit" value="提交评论">
    </form>

    <%
        // 连接数据库
        Connection conn = null;
        PreparedStatement pstmt = null;
        ResultSet rs = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/your_database", "username", "password");

            // 查询所有评论
            pstmt = conn.prepareStatement("SELECT * FROM comments WHERE parent_id IS NULL ORDER BY created_at DESC");
            rs = pstmt.executeQuery();

            while (rs.next()) {
                int commentId = rs.getInt("id");
                String content = rs.getString("content");
                int userId = rs.getInt("user_id");
                Timestamp createdAt = rs.getTimestamp("created_at");
    %>
                <div>
                    <p><%= content %></p>
                    <p>用户ID: <%= userId %>, 时间: <%= createdAt %></p>
                    <a href="reply.jsp?id=<%= commentId %>">回复</a>

                    <!-- 查询该评论的所有回复 -->
                    <%
                        pstmt = conn.prepareStatement("SELECT * FROM comments WHERE parent_id = ?");
                        pstmt.setInt(1, commentId);
                        rs = pstmt.executeQuery();

                        while (rs.next()) {
                            String replyContent = rs.getString("content");
                            int replyUserId = rs.getInt("user_id");
                            Timestamp replyCreatedAt = rs.getTimestamp("created_at");
                    %>
                            <div style="margin-left: 20px;">
                                <p><%= replyContent %></p>
                                <p>用户ID: <%= replyUserId %>, 时间: <%= replyCreatedAt %></p>
                            </div>
                    <%
                        }
                    %>
                </div>
    <%
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (rs != null) rs.close();
            if (pstmt != null) pstmt.close();
            if (conn != null) conn.close();
        }
    %>
</body>
</html>

3. 提交评论的JSP页面

创建一个JSP页面来处理评论的提交。

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

    Connection conn = null;
    PreparedStatement pstmt = null;
    try {
        Class.forName("com.mysql.jdbc.Driver");
        conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/your_database", "username", "password");

        pstmt = conn.prepareStatement("INSERT INTO comments (content, user_id, parent_id) VALUES (?, ?, ?)");
        pstmt.setString(1, content);
        pstmt.setInt(2, 1); // 假设当前用户ID为1
        pstmt.setInt(3, parentId);
        pstmt.executeUpdate();

        response.sendRedirect("index.jsp");
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        if (pstmt != null) pstmt.close();
        if (conn != null) conn.close();
    }
%>

4. 回复评论的JSP页面

创建一个JSP页面来处理回复的提交。

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

    Connection conn = null;
    PreparedStatement pstmt = null;
    try {
        Class.forName("com.mysql.jdbc.Driver");
        conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/your_database", "username", "password");

        pstmt = conn.prepareStatement("INSERT INTO comments (content, user_id, parent_id) VALUES (?, ?, ?)");
        pstmt.setString(1, content);
        pstmt.setInt(2, 1); // 假设当前用户ID为1
        pstmt.setInt(3, commentId);
        pstmt.executeUpdate();

        response.sendRedirect("index.jsp");
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        if (pstmt != null) pstmt.close();
        if (conn != null) conn.close();
    }
%>

优势与应用场景

优势：
- 动态内容生成：JSP允许在服务器端动态生成HTML内容，适合需要实时更新的应用。
- 易于集成：可以与Java EE的其他技术（如Servlet、EJB等）无缝集成。
- 丰富的标签库：JSTL（JSP Standard Tag Library）提供了许多有用的标签，简化了页面开发。