纯Servlet和JSP实现的博客小程序

package yitian.learn.dao; import yitian.learn.entity.Article; import yitian.learn.entity.Comment; import yitian.learn.entity.User; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.time.LocalDateTime; import java.util.ArrayList; import java.util.List; import java.util.Optional; import java.util.stream.Collectors; public class ArticleDaoImpl implements ArticleDao { private Connection connection; public ArticleDaoImpl() { connection = JdbcUtil.getConnection(); } @Override public void add(Article article) { try (PreparedStatement statement = connection.prepareStatement("INSERT INTO article(title,content,create_time,modify_time,author) VALUES(?,?,?,?,?)")) { statement.setString(1, article.getTitle()); statement.setString(2, article.getContent()); statement.setObject(3, article.getCreateTime()); statement.setObject(4, article.getModifyTime()); statement.setInt(5, article.getAuthor().getId()); statement.executeUpdate(); } catch (SQLException e) { throw new RuntimeException(e); } } @Override public Optional<Article> find(int id) { Article article = null; try (PreparedStatement statement = connection.prepareStatement("SELECT id,title,content,author,create_time,modify_time FROM article WHERE id=?")) { statement.setInt(1, id); ResultSet rs = statement.executeQuery(); while (rs.next()) { article = new Article(); article.setId(rs.getInt(1)); article.setTitle(rs.getString(2)); article.setContent(rs.getString(3)); UserDao userDao = DaoFactory.getUserDao(); Optional<User> user = userDao.find(rs.getInt(4)); user.ifPresent(article::setAuthor); article.setCreateTime(rs.getObject(5, LocalDateTime.class)); article.setModifyTime(rs.getObject(6, LocalDateTime.class)); } } catch (SQLException e) { throw new RuntimeException(e); } return Optional.ofNullable(article); } @Override public void update(Article article) { try (PreparedStatement statement = connection.prepareStatement("UPDATE article SET title=?,content=?,modify_time=? WHERE id=?")) { statement.setString(1, article.getTitle()); statement.setString(2, article.getContent()); statement.setObject(3, article.getModifyTime()); statement.setInt(4, article.getId()); statement.executeUpdate(); } catch (SQLException e) { throw new RuntimeException(e); } } @Override public void delete(int id) { try (PreparedStatement statement = connection.prepareStatement("DELETE FROM article WHERE id=?")) { statement.setInt(1, id); statement.executeUpdate(); } catch (SQLException e) { throw new RuntimeException(e); } } @Override public List<Article> listAllOf(User author) { List<Article> articles = new ArrayList<>(); try (PreparedStatement statement = connection.prepareStatement("SELECT id,title,content,create_time,modify_time FROM article WHERE author=?")) { statement.setInt(1, author.getId()); ResultSet rs = statement.executeQuery(); while (rs.next()) { Article article = new Article(); article.setId(rs.getInt(1)); article.setTitle(rs.getString(2)); article.setContent(rs.getString(3)); article.setCreateTime(rs.getObject(4, LocalDateTime.class)); article.setModifyTime(rs.getObject(5, LocalDateTime.class)); article.setAuthor(author); CommentDao commentDao = DaoFactory.getCommentDao(); List<Comment> comments = commentDao.listAllOf(article); article.setComments(comments); articles.add(article); } } catch (SQLException e) { throw new RuntimeException(e); } return articles; } @Override public List<Article> listAll() { List<Article> articles = new ArrayList<>(); try (PreparedStatement statement = connection.prepareStatement("SELECT id,title,content,create_time,modify_time,author FROM article ")) { ResultSet rs = statement.executeQuery(); while (rs.next()) { Article article = new Article(); article.setId(rs.getInt(1)); article.setTitle(rs.getString(2)); article.setContent(rs.getString(3)); article.setCreateTime(rs.getObject(4, LocalDateTime.class)); article.setModifyTime(rs.getObject(5, LocalDateTime.class)); UserDao userDao = DaoFactory.getUserDao(); Optional<User> user = userDao.find(rs.getInt(6)); user.ifPresent(article::setAuthor); CommentDao commentDao = DaoFactory.getCommentDao(); List<Comment> comments = commentDao.listAllOf(article); article.setComments(comments); articles.add(article); } } catch (SQLException e) { throw new RuntimeException(e); } return articles; } }