javaweb 新闻发布dao

在Java Web中，DAO（Data Access Object，数据访问对象）是一个设计模式，用于将数据库操作封装起来，使得业务逻辑与底层数据访问解耦。对于新闻发布系统中的DAO，它通常会负责与数据库交互，执行插入、查询、更新和删除新闻信息的操作。

新闻发布DAO可能包含以下几个关键方法：

1. `saveNews(News news)`: 用于保存一条新的新闻，其中`News`是新闻对象，包含了标题、内容、作者等属性。
2. `getNewsById(long id)`: 根据新闻ID获取一条特定的新闻。
3. `getNewsByCategory(String category)`: 按照类别搜索新闻。
4. `updateNews(News news, long id)`: 更新已有新闻的信息。
5. `deleteNews(long id)`: 删除指定ID的新闻。
6. `getAllNews()`: 获取所有新闻列表。

在实现时，DAO可能会使用JDBC（Java Database Connectivity）或者ORM（Object-Relational Mapping）框架如Hibernate或MyBatis，根据数据库查询语句动态生成或调用存储过程。

相关问题

设计一个基于JavaWeb语言的新闻发布管理系统代码

好的，下面是一个简单的基于JavaWeb语言的新闻发布管理系统的代码示例，包括数据库设计和部分后端代码：

1. 数据库设计

CREATE TABLE `t_news` (
`id` int(11) NOT NULL AUTO_INCREMENT COMMENT '新闻ID',
`title` varchar(255) NOT NULL COMMENT '新闻标题',
`content` text NOT NULL COMMENT '新闻内容',
`author` varchar(50) NOT NULL COMMENT '新闻作者',
`create_time` datetime NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
`update_time` datetime NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '更新时间',
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='新闻表';

2. 后端代码

(1) News.java

package com.example.news.entity;

import java.util.Date;

public class News {
private int id;
private String title;
private String content;
private String author;
private Date createTime;
private Date updateTime;

// 省略getter和setter方法
}

(2) NewsDao.java

package com.example.news.dao;

import com.example.news.entity.News;

import java.sql.*;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

public class NewsDao {
private static final String JDBC_URL = "jdbc:mysql://localhost:3306/news_db?useSSL=false&serverTimezone=UTC";
private static final String JDBC_USER = "root";
private static final String JDBC_PASSWORD = "123456";

public List<News> listNews() throws SQLException {
List<News> newsList = new ArrayList<>();

try (Connection conn = DriverManager.getConnection(JDBC_URL, JDBC_USER, JDBC_PASSWORD)) {
String sql = "SELECT * FROM t_news ORDER BY create_time DESC";
try (PreparedStatement stmt = conn.prepareStatement(sql)) {
try (ResultSet rs = stmt.executeQuery()) {
while (rs.next()) {
int id = rs.getInt("id");
String title = rs.getString("title");
String content = rs.getString("content");
String author = rs.getString("author");
Date createTime = rs.getTimestamp("create_time");
Date updateTime = rs.getTimestamp("update_time");
News news = new News();
news.setId(id);
news.setTitle(title);
news.setContent(content);
news.setAuthor(author);
news.setCreateTime(createTime);
news.setUpdateTime(updateTime);
newsList.add(news);
}
}
}
}

return newsList;
}

public void addNews(News news) throws SQLException {
try (Connection conn = DriverManager.getConnection(JDBC_URL, JDBC_USER, JDBC_PASSWORD)) {
String sql = "INSERT INTO t_news(title, content, author) VALUES (?, ?, ?)";
try (PreparedStatement stmt = conn.prepareStatement(sql)) {
stmt.setString(1, news.getTitle());
stmt.setString(2, news.getContent());
stmt.setString(3, news.getAuthor());
stmt.executeUpdate();
}
}
}
}

(3) NewsServlet.java

package com.example.news.servlet;

import com.example.news.dao.NewsDao;
import com.example.news.entity.News;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.sql.SQLException;
import java.util.List;

public class NewsServlet extends HttpServlet {
private NewsDao newsDao;

public void init() throws ServletException {
newsDao = new NewsDao();
}

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
try {
List<News> newsList = newsDao.listNews();
request.setAttribute("newsList", newsList);
request.getRequestDispatcher("/news.jsp").forward(request, response);
} catch (SQLException e) {
throw new ServletException("Failed to list news", e);
}
}

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String title = request.getParameter("title");
String content = request.getParameter("content");
String author = request.getParameter("author");
News news = new News();
news.setTitle(title);
news.setContent(content);
news.setAuthor(author);
try {
newsDao.addNews(news);
response.sendRedirect(request.getContextPath() + "/news");
} catch (SQLException e) {
throw new ServletException("Failed to add news", e);
}
}
}

以上是一个简单的基于JavaWeb语言的新闻发布管理系统的代码示例，仅供参考。其中NewsDao.java和NewsServlet.java是关键部分，News.java是新闻实体类。需要注意的是，这里的代码只是示例，实际开发中需要根据实际需求进行修改和完善。

使用javaweb写一个用户注册数据保存至数据库的代码，并要求登录时进行匹配，匹配成功跳至新闻发布系统主页面。

好的，我可以帮您撰写一份JavaWeb用户注册和登录的代码。首先，您需要使用JavaWeb框架，如Spring MVC或Struts2，以及JDBC连接数据库。以下是一个简单的实现：

1. 创建一个用户实体类User，包含以下属性：

public class User {
    private int id;
    private String username;
    private String password;
    // getter和setter方法
}

2. 创建一个Dao类UserDao，实现用户信息的存储和查询：

public class UserDao {
    public void save(User user) {
        Connection conn = null;
        PreparedStatement stmt = null;
        try {
            conn = DBUtil.getConnection();
            String sql = "insert into user (username, password) values (?, ?)";
            stmt = conn.prepareStatement(sql);
            stmt.setString(1, user.getUsername());
            stmt.setString(2, user.getPassword());
            stmt.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(conn, stmt, null);
        }
    }

    public User findByUsername(String username) {
        Connection conn = null;
        PreparedStatement stmt = null;
        ResultSet rs = null;
        User user = null;
        try {
            conn = DBUtil.getConnection();
            String sql = "select * from user where username=?";
            stmt = conn.prepareStatement(sql);
            stmt.setString(1, username);
            rs = stmt.executeQuery();
            if (rs.next()) {
                user = new User();
                user.setId(rs.getInt("id"));
                user.setUsername(rs.getString("username"));
                user.setPassword(rs.getString("password"));
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(conn, stmt, rs);
        }
        return user;
    }
}

3. 创建一个控制器类UserController，用于处理用户注册和登录：

public class UserController {
    private UserDao userDao = new UserDao();

    public void register(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username = request.getParameter("username");
        String password = request.getParameter("password");

        User user = new User();
        user.setUsername(username);
        user.setPassword(password);
        userDao.save(user);

        request.getRequestDispatcher("/login.jsp").forward(request, response);
    }

    public void login(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username = request.getParameter("username");
        String password = request.getParameter("password");

        User user = userDao.findByUsername(username);
        if (user != null && user.getPassword().equals(password)) {
            HttpSession session = request.getSession();
            session.setAttribute("user", user);
            response.sendRedirect(request.getContextPath() + "/news/list");
        } else {
            request.setAttribute("message", "用户名或密码错误");
            request.getRequestDispatcher("/login.jsp").forward(request, response);
        }
    }
}

4. 创建一个登录页面login.jsp和注册页面register.jsp，以及一个处理注册和登录的Servlet：

public class UserServlet extends HttpServlet {
    private UserController userController = new UserController();

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String path = request.getServletPath();
        if ("/register.jsp".equals(path)) {
            request.getRequestDispatcher("/register.jsp").forward(request, response);
        } else {
            request.getRequestDispatcher("/login.jsp").forward(request, response);
        }
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String path = request.getServletPath();
        if ("/register".equals(path)) {
            userController.register(request, response);
        } else {
            userController.login(request, response);
        }
    }
}

5. 配置web.xml文件，将UserServlet映射到URL路径：

<servlet>
    <servlet-name>UserServlet</servlet-name>
    <servlet-class>com.example.servlet.UserServlet</servlet-class>
</servlet>

<servlet-mapping>
    <servlet-name>UserServlet</servlet-name>
    <url-pattern>/register</url-pattern>
</servlet-mapping>

<servlet-mapping>
    <servlet-name>UserServlet</servlet-name>
    <url-pattern>/login</url-pattern>
</servlet-mapping>

以上是一个简单的JavaWeb用户注册和登录的代码实现，您可以根据自己的需求进行修改和扩展。