java - 如何从标签名称更改的 xml 中获取 api 数据

Question

所以我尝试使用 openweathermap api 进行五天的天气预报。它返回五天天气预报的 xml here

我一直在尝试使用代码 NodeList nodeList = doc.getElementsByTagName("time"); 获取信息。如果您检查 xml，您将看到标签 <time>包含每 2 小时范围的预测。但问题是我似乎无法从这些标签中获取任何内容，因为名称实际上是 <tag="date range""time range" to "time range + 3hrs"> 。

 try {
        DocumentBuilderFactory dbFactory = 
        DocumentBuilderFactory.newInstance();
        DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
        Document doc = dBuilder.parse(this.fiveDayForecastURL);
        doc.getDocumentElement().normalize();

        NodeList nodeList = doc.getElementsByTagName("time");
        for (int i = 0; i < nodeList.getLength(); i++){
            Node node = nodeList.item(i);
            NamedNodeMap namedNodeMap = node.getAttributes();
            Node attr = namedNodeMap.getNamedItem("max");
            // just trying to grab anything from inside these tags
            // but ideally would want min and max temp for the range
            if (node.getNodeType() == Node.ELEMENT_NODE){
                System.out.println(attr);
                // always prints [time: null]
            }
            System.out.println(node);
            // always prints null 
        }
    } catch (ParserConfigurationException | IOException ex) {
        ex.printStackTrace();
    } catch (org.xml.sax.SAXException e) {
        e.printStackTrace();
    }

我确定我遗漏了一些代码行或其他内容，但是有没有办法获取时间标签之间的所有内容，即使标签名称每次都会更改？谢谢

Answer 1

首先，我忘记了用 DOM 解析器解析 XML 是多么麻烦。

您考虑过requesting the returned data as JSON然后您可以使用 gson 进行解析？

所以 - 您的方向是正确的，但为了获得给定时间段内的最低/最高温度，您需要继续深入 DOM 层次结构。

温度是时间的子元素，因此您需要获取它，然后从中获取最小和最大属性值。

类似于:

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import java.io.IOException;

import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
import org.w3c.dom.Node;
import org.w3c.dom.NamedNodeMap;

public class Test {
    private static final String FIVE_DAY_FORECAST_URL = 
        "https://api.openweathermap.org/data/2.5/forecast?q=Denver&appid=8984d739fa91d7031fff0e84a3d2c520&mode=xml&units=imperial";

    private static final String TIME_ELEM = "time";
    private static final String TEMPERATURE_ELEM = "temperature";
    private static final String TIME_FROM_ATTR = "from";
    private static final String TIME_TO_ATTR = "to";
    private static final String TEMPERATURE_MIN_ATTR = "min";
    private static final String TEMPERATURE_MAX_ATTR = "max";

    private static void getWeatherForcast() {
        try {
            final DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
            final DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
            final Document doc = dBuilder.parse(FIVE_DAY_FORECAST_URL);
            doc.getDocumentElement().normalize();

            NodeList nodeList = doc.getElementsByTagName(TIME_ELEM);
            for (int i = 0; i < nodeList.getLength(); i++) {
                final Node node = nodeList.item(i);
                final NamedNodeMap namedNodeMap = node.getAttributes();
                final Node fromAttr = namedNodeMap.getNamedItem(TIME_FROM_ATTR);
                final Node toAttr = namedNodeMap.getNamedItem(TIME_TO_ATTR);
                System.out.println("Time: " + fromAttr + " " + toAttr);
                final NodeList timeChildren = node.getChildNodes();
                for (int j = 0; j < timeChildren.getLength(); j++) {
                    final Node timeChild = timeChildren.item(j);
                    if (TEMPERATURE_ELEM.equals(timeChild.getNodeName())) {
                        final NamedNodeMap temperatureAttrMap = timeChild.getAttributes();
                        final String minTemp = temperatureAttrMap.getNamedItem(TEMPERATURE_MIN_ATTR).getNodeValue();
                        final String maxTemp = temperatureAttrMap.getNamedItem(TEMPERATURE_MAX_ATTR).getNodeValue();
                        System.out.println("min: " + minTemp + " max: " + maxTemp);
                    }
                }

            }
        } catch (ParserConfigurationException | IOException ex) {
            ex.printStackTrace();
        } catch (org.xml.sax.SAXException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        getWeatherForcast();
    }
}