java - 如何从一个表中抓取另一表中具有相同类的数据

Question

我必须从有许多表的网站上抓取数据并将其保存在 .csv 文件中。我只抓取一张具有 marketData 类的表的数据。但是，还有另外两个表具有相同的类别。目前，我的代码正在从具有 marketData 类的表中获取所有数据。如何从一张表中抓取数据并跳过其他表？我的代码如下。

public class ComMarket_summary {

boolean writeCSVToConsole = true;
boolean writeCSVToFile = true;
boolean sortTheList = true;
boolean writeToConsole;
boolean writeToFile;
public static Document doc = null;
public static Elements tbodyElements = null;
public static Elements elements = null;
public static Elements tdElements = null;
public static Elements trElement2 = null;
public static String Dcomma = ",";
public static String line = "";
public static ArrayList<Elements> sampleList = new ArrayList<Elements>();

public static void createConnection() throws IOException {
    System.setProperty("http.proxyHost", "191.1.1.202");
    System.setProperty("http.proxyPort", "8080");
    String tempUrl = "http://www.psx.com.pk/phps/mktSummary.php";
    doc = Jsoup.parse(new URL(tempUrl), 1000);        
    System.out.println("Successfully Connected");
}

public static void parsingHTML() throws Exception {

    for (Element table : doc.getElementsByTag("table")) {
        for (Element trElement : table.getElementsByTag("tr")) {
            File fold = new File("C:\\market_smry.csv");
            fold.delete();
            File fnew = new File("C:\\market_smry.csv");
            trElement2 = trElement.getElementsByTag("tr");
            tdElements = trElement.getElementsByTag("td");
            FileWriter sb = new FileWriter(fnew, true);

            if (table.hasClass("marketData")) {

                for (Iterator<Element> it = trElement2.iterator(); it.hasNext();) {
                    if (it.hasNext()) {
                        sb.append("\r\n");

                    }

                    for (Iterator<Element> it2 = trElement2.iterator(); it.hasNext();) {
                        Element tdElement2 = it.next();
                        final String content = tdElement2.text();
                        if (it2.hasNext()) {

                            sb.append(formatData(content));
                            sb.append("   ,   ");

                        }

                    }

                    System.out.println(sb.toString());
                    sb.flush();
                    sb.close();
                }
            }
            System.out.println(sampleList.add(tdElements));

        }
    }
}
private static final SimpleDateFormat FORMATTER_MMM_d_yyyy = new SimpleDateFormat("MMM d, yyyy", Locale.US);
private static final SimpleDateFormat FORMATTER_dd_MMM_yyyy = new SimpleDateFormat("dd-MMM-YYYY", Locale.US);

public static String formatData(String text) {
    String tmp = null;

    try {
        Date d = FORMATTER_MMM_d_yyyy.parse(text);
        tmp = FORMATTER_dd_MMM_yyyy.format(d);
    } catch (ParseException pe) {
        tmp = text;
    }

    return tmp;
}

public static void main(String[] args) throws IOException, Exception {
    createConnection();
    parsingHTML();

}

P.S:我使用的是 JDK 1.8、Jre 1.8、jsoup 1.8。

Answer 1

您可以使用更具体的选择器来优化代码。

for (Element table : doc.select("table.marketData")) {
//Process table
}

如果您只想处理页面上的特定表格，可以通过其索引访问该表格。

Elements tables = doc.select("table.marketData");
Element table = tables.get(1);