student-management/src/main/java/com/student/dao/impl/AnnouncementDaoImpl.java

package com.student.dao.impl;

import com.student.bean.Announcement;
import com.student.dao.AnnouncementDao;
import com.student.util.DBUtil;

import java.sql.Connection;
import java.sql.Date;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Timestamp;
import java.sql.Types;
import java.util.ArrayList;
import java.util.List;

public class AnnouncementDaoImpl implements AnnouncementDao {

    private static final String BASE_SQL =
            "SELECT a.id, a.title, a.content, a.publisher_id, a.is_top, a.expire_date, a.create_time, "
                    + "u.real_name AS publisher_name FROM announcement a "
                    + "LEFT JOIN users u ON a.publisher_id = u.id ";

    @Override
    public Announcement findById(int id) {
        List<Announcement> list = queryList(BASE_SQL + " WHERE a.id = ?", id);
        return list.isEmpty() ? null : list.get(0);
    }

    @Override
    public boolean insert(Announcement announcement) {
        String sql = "INSERT INTO announcement (title, content, publisher_id, is_top, expire_date) VALUES (?, ?, ?, ?, ?)";
        return executeUpdate(sql, announcement);
    }

    @Override
    public boolean update(Announcement announcement) {
        String sql = "UPDATE announcement SET title=?, content=?, publisher_id=?, is_top=?, expire_date=? WHERE id=?";
        Connection conn = null;
        PreparedStatement ps = null;
        try {
            conn = DBUtil.getConnection();
            ps = conn.prepareStatement(sql);
            fillParams(ps, announcement);
            ps.setInt(6, announcement.getId());
            return ps.executeUpdate() > 0;
        } catch (SQLException e) {
            throw new RuntimeException("更新公告失败", e);
        } finally {
            DBUtil.close(conn, ps);
        }
    }

    @Override
    public boolean delete(int id) {
        String sql = "DELETE FROM announcement WHERE id = ?";
        Connection conn = null;
        PreparedStatement ps = null;
        try {
            conn = DBUtil.getConnection();
            ps = conn.prepareStatement(sql);
            ps.setInt(1, id);
            return ps.executeUpdate() > 0;
        } catch (SQLException e) {
            throw new RuntimeException("删除公告失败", e);
        } finally {
            DBUtil.close(conn, ps);
        }
    }

    @Override
    public List<Announcement> findAll() {
        return queryList(BASE_SQL + " ORDER BY a.is_top DESC, a.create_time DESC");
    }

    @Override
    public List<Announcement> findActive() {
        return queryList(BASE_SQL + " WHERE (a.expire_date IS NULL OR a.expire_date >= CURDATE()) "
                + "ORDER BY a.is_top DESC, a.create_time DESC");
    }

    private boolean executeUpdate(String sql, Announcement announcement) {
        Connection conn = null;
        PreparedStatement ps = null;
        try {
            conn = DBUtil.getConnection();
            ps = conn.prepareStatement(sql);
            fillParams(ps, announcement);
            return ps.executeUpdate() > 0;
        } catch (SQLException e) {
            throw new RuntimeException("保存公告失败", e);
        } finally {
            DBUtil.close(conn, ps);
        }
    }

    private void fillParams(PreparedStatement ps, Announcement a) throws SQLException {
        ps.setString(1, a.getTitle());
        ps.setString(2, a.getContent());
        if (a.getPublisherId() != null) {
            ps.setInt(3, a.getPublisherId());
        } else {
            ps.setNull(3, Types.INTEGER);
        }
        ps.setInt(4, a.getIsTop() != null ? a.getIsTop() : 0);
        if (a.getExpireDate() != null) {
            ps.setDate(5, new Date(a.getExpireDate().getTime()));
        } else {
            ps.setNull(5, Types.DATE);
        }
    }

    private List<Announcement> queryList(String sql, Object... params) {
        List<Announcement> list = new ArrayList<>();
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;
        try {
            conn = DBUtil.getConnection();
            ps = conn.prepareStatement(sql);
            for (int i = 0; i < params.length; i++) {
                ps.setObject(i + 1, params[i]);
            }
            rs = ps.executeQuery();
            while (rs.next()) {
                list.add(mapRow(rs));
            }
        } catch (SQLException e) {
            throw new RuntimeException("查询公告失败", e);
        } finally {
            DBUtil.close(conn, ps, rs);
        }
        return list;
    }

    private Announcement mapRow(ResultSet rs) throws SQLException {
        Announcement a = new Announcement();
        a.setId(rs.getInt("id"));
        a.setTitle(rs.getString("title"));
        a.setContent(rs.getString("content"));
        int publisherId = rs.getInt("publisher_id");
        a.setPublisherId(rs.wasNull() ? null : publisherId);
        a.setIsTop(rs.getInt("is_top"));
        Date expireDate = rs.getDate("expire_date");
        if (expireDate != null) {
            a.setExpireDate(new java.util.Date(expireDate.getTime()));
        }
        Timestamp createTime = rs.getTimestamp("create_time");
        if (createTime != null) {
            a.setCreateTime(new java.util.Date(createTime.getTime()));
        }
        a.setPublisherName(rs.getString("publisher_name"));
        return a;
    }
}