我正在尝试使用 url xml 解析，但看起来我一直得到一个空的 xml

Question

我正在尝试从名为的天气 API 获取信息，即使当我发出请求时我收到了响应，但是当我尝试仅获取响应的特定部分时，每次有人可以提供帮助时，我都会得到空响应？ 这是我处理程序的代码：

package weathercalls;
import java.util.ArrayList;
import org.xml.sax.Attributes;
import org.xml.sax.helpers.DefaultHandler;
public class Handler extends DefaultHandler
{
// Create three array lists to store the data
public ArrayList<Integer> lows = new ArrayList<Integer>();
public ArrayList<Integer> highs = new ArrayList<Integer>();
public ArrayList<String> regions = new ArrayList<String>();

// Make sure that the code in DefaultHandler's
// constructor is called:
public Handler()
{
super();
}

/*** Below are the three methods that we are extending ***/
@Override
public void startDocument()
{
System.out.println("Start document");
}

@Override
public void endDocument()
{
System.out.println("End document");
}

// This is where all the work is happening:
@Override
public void startElement(String uri, String name, String qName, Attributes atts)
{
if(qName.compareTo("region") == 0)
{
String region = atts.getLocalName(0);
System.out.println("Day: " + region);
this.regions.add(region);
}
if(qName.compareToIgnoreCase("wind_degree") == 0)
{
int low =  atts.getLength();
System.out.println("Low: " + low);
this.lows.add(low);
}
if(qName.compareToIgnoreCase("high") == 0)
{
int high = Integer.parseInt(atts.getValue(0));
System.out.println("High: " + high);
this.highs.add(high);
}
}
}

这是我的主要文件代码：

package weathercalls;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;
import java.net.URLConnection;
import org.xml.sax.InputSource;
import org.xml.sax.XMLReader;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import org.xml.sax.SAXException;


public class weatherCalls {

public static void main(String[] args) throws Exception {
//Main url
String main_url = "http://api.weatherapi.com/v1/";
//Live or Weekly forecast
String live_weather = "current.xml?key=";
//String sevendays_weather = "orecast.xml?key=";
//API Key + q
String API_Key = "c2e285e55db74def97f151114201701&q=";
//Location Setters
String location = "London";

InputSource inSource = null;
InputStream in = null;
XMLReader xr = null;
/**
URL weather = new URL(main_url + live_weather + API_Key + location);
URLConnection yc = weather.openConnection();
BufferedReader in1 = new BufferedReader(
new InputStreamReader(
yc.getInputStream()));
String inputLine;
while ((inputLine = in1.readLine()) != null)
System.out.println(inputLine);
in1.close();**/
try
{
// Turn the string into a URL object
String complete_url = main_url + live_weather + API_Key + location;
URL urlObject = new URL(complete_url);
// Open the stream (which returns an InputStream):
in = urlObject.openStream();
/** Now parse the data (the stream) that we received back ***/
// Create an XML reader
SAXParserFactory parserFactory = SAXParserFactory.newInstance();
SAXParser parser = parserFactory.newSAXParser();
xr = parser.getXMLReader();
// Tell that XML reader to use our special Google Handler
Handler ourSpecialHandler = new Handler();
xr.setContentHandler(ourSpecialHandler);
// We have an InputStream, but let's just wrap it in
// an InputSource (the SAX parser likes it that way)
inSource = new InputSource(in);
// And parse it!
xr.parse(inSource);
System.out.println(complete_url);
System.out.println(urlObject);
System.out.println(in);
System.out.println(xr);
System.out.println(inSource);
System.out.println(parser);
}
catch(IOException ioe)
{
ioe.printStackTrace();
}
catch(SAXException se)
{
se.printStackTrace();
}
}
}

这是我的控制台打印：

Start document
Day: null
Low: 0
End document
http://api.weatherapi.com/v1/current.xml?key=c2e285e55db74def97f151114201701&q=London
http://api.weatherapi.com/v1/current.xml?key=c2e285e55db74def97f151114201701&q=London
sun.net.www.protocol.http.HttpURLConnection$HttpInputStream@2471cca7
com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser@5fe5c6f
org.xml.sax.InputSource@6979e8cb
com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl@763d9750

Answer 1

我认为您正在尝试从 XML 标签中提取值，如果是这种情况，那么您做错了。属性对象包含特定标签的属性，要获取该值，您必须做一些额外的工作。与标记的开头类似，标记的内容和结尾有单独的事件。current_tag变量将跟踪当前正在处理的标记。下面是一个示例代码：

class Handler extends DefaultHandler {
// Create three array lists to store the data
public ArrayList<Integer> lows = new ArrayList<Integer>();
public ArrayList<Integer> highs = new ArrayList<Integer>();
public ArrayList<String> regions = new ArrayList<String>();

// Make sure that the code in DefaultHandler's
// constructor is called:
public Handler() {
super();
}

/*** Below are the three methods that we are extending ***/
@Override
public void startDocument() {
System.out.println("Start document");
}

@Override
public void endDocument() {
System.out.println("End document");
}
//Keeps track of the current tag;
String currentTag = "";
// This is where all the work is happening:
@Override
public void startElement(String uri, String name, String qName, Attributes atts) {
//Save the current tag being handled
currentTag = qName;
}
//Detect end tag
@Override
public void endElement(String uri, String localName, String qName) throws SAXException {
//Reset it
currentTag = "";
}
@Override
public void characters(char[] ch, int start, int length) throws SAXException {
//Rules based on current tag
switch (currentTag) {
case "region":
String region = String.valueOf(ch, start, length);
this.regions.add(region);
System.out.println("Day: " + region);
break;
case "wind_degree":
int low = Integer.parseInt(String.valueOf(ch, start, length));
System.out.println("Low: " + low);
this.lows.add(low);
break;
case "high":
int high = Integer.parseInt(String.valueOf(ch, start, length));
System.out.println("High: " + high);
this.highs.add(high);
break;
}
}}

注意：请不要在互联网上分享您的API密钥或密码。