根据提供的ID打印一篇文章

Question

我正在尝试根据提供的ID打印出文章。我有一个方法GetArticleById，如果文章的存在或返回NULL，则返回该文章，如果不存在。我也有一个start((方法，该方法提示用户输入ID并在文章中打印出来。我不确定是否正确实现了GetArticleById。另外，我需要一些方向启动((方法来检查是否存在输入的ID。

public Article getArticleById(int id, Connection conn) throws SQLException {
    try (PreparedStatement stmt = conn.prepareStatement(
            "SELECT * FROM articles  WHERE id = ?")) {
        stmt.setInt(1, id);
        try (ResultSet r = stmt.executeQuery()) {
            if (r.next()) {
                return getAllArticles(conn).get(id);
            } else {
                return null;
            }
        } 
    }
}
private void start() throws IOException, SQLException {
    try (Connection conn = DBConnectionUtils.getConnectionFromSrcFolder("connection.properties")) {
        System.out.print("Enter the article id: > ");
        int id = Integer.parseInt(Keyboard.readInput());
    }
}

Answer 1

看起来不错，您只需要在start中调用getArticleById方法：

private void start() throws IOException, SQLException {
    try (Connection conn = DBConnectionUtils.getConnectionFromSrcFolder("connection.properties")) {
        System.out.print("Enter the article id: > ");
        int id = Integer.parseInt(Keyboard.readInput());
        Article article = getArticleById(id, conn);
        // DO SOMETHING WITH ARTICLE
    }
}

希望这会有所帮助。