java - 如何将扫描的网址插入网址表？

Question

我正在编写一个网络爬虫，但遇到了一些麻烦。这是我想要做的一些伪代码:

for every url in url-list {
    urlid = NextURLID;

    Insert urlid and url to their respective columns URL table

    NextURLID++;
}

这是我到目前为止所拥有的:

void startCrawl() {
        int NextURLID = 0;
        int NextURLIDScanned = 0;

        try
        {
            openConnection(); //Open the database
        }
        catch (SQLException | IOException e)
        {
            e.printStackTrace();
        }

        String url = "http://jsoup.org";
        print("Fetching %s...", url);

        Document doc = Jsoup.connect(url).get();
        Elements links = doc.getElementsByTag("a");

        for (Element link : links) {
            urlID = NextURLID;

            //Code to insert (urlid, url)  to the URL table

            NextURLID++;

        }
}

如您所见，我还没有将 url 插入表中的代码。我认为它会是这样的:

stat.executeUpdate("INSERT INTO urls VALUES ('"+urlID+"','"+url+"')");

但是如何在每次循环迭代时使用新的 url 覆盖 urlID 和 url 变量？谢谢

Answer 1

根据您的情况，PreparementStatement 更合适:

String insertURL = "INSERT INTO urls(urlID, url) VALUES (?, ?)";
PreparedStatement ps = dbConnection.prepareStatement(insertURL);

for (Element link : links) {
     ps.setInt(1, NextURLID);
     ps.setInt(2, link.attr("abs:href"));  
     ps.executeUpdate();

     NextURLID++;
}

// ...