在 Java 中获取 XML 文件的问题

Question

我正在尝试在 Android 应用程序中使用 Google 的非官方天气 API。

我使用这个代码：

//get the text from the edit text
    userZip = zipCode.getText().toString();
    //create a link using the zip code
    //TODO sanitize input
    System.out.println(userZip);
    link = "http://www.google.com/ig/api?weather=" + userZip;
    System.out.println(link);
    //connect to the link
    URL googleWeatherService = null;
    try {
        googleWeatherService = new URL(link);
    } catch (MalformedURLException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    } 
    SAXBuilder parser = new SAXBuilder();
    try {
        doc = parser.build(googleWeatherService);
    } catch (JDOMException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

但我收到错误 java.io.IOException 无法打开 http://www.google.com/ig/api?weather=08003（仅以 08003 为例）。

如果你转到 FF 中的链接，你会得到一个很好的 XML 天气文件，那我做错了什么？

Answer 1

我在使用 JDOM2 时遇到过这个问题，它实际上是变相的 NetworkOnMainThreadException。将其从主线程中移除，一切正常。

new Thread(new Runnable() {
            @Override
            public void run() {
                <your code>
            }
        }).start();

Answer 2

您能否成功检索其他 URI？

您可能遇到了 JVM 配置问题。在我遇到的大多数环境中，如果您的机器配置为使 Web 浏览器可以成功发出 HTTP 请求，那么 Java 也将能够成功发出它们。但是我听说当你在代理服务器后面时需要特殊的 JVM 配置，我不知道在 Android 环境中是否需要类似的配置。

Answer 3

这对我来说非常有效：

package weather;

import org.dom4j.Document;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.URL;

/**
 * GoogleWeather
 * @author Michael
 * @since 2/12/11
 */
public class GoogleWeather
{

    public static void main(String[] args)
    {
        for (String userZip : args)
        {
            BufferedReader br = null;
            try
            {
                String link = "http://www.google.com/ig/api?weather=" + userZip;
                System.out.println(link);
                URL googleWeatherService = new URL(link);
                br = new BufferedReader(new InputStreamReader(googleWeatherService.openStream()));
                SAXReader reader = new SAXReader();
                Document document = reader.read(googleWeatherService);
                OutputFormat format = OutputFormat.createPrettyPrint();
                XMLWriter writer = new XMLWriter(System.out, format);
                writer.write(document);
            }
            catch (Exception e)
            {
                e.printStackTrace();
            }
            finally
            {
                close(br);
            }
        }
    }

    private static void close(BufferedReader br)
    {
        try
        {
            if (br != null)
            {
                br.close();
            }
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
    }
}

这是它带回来的结果：

<?xml version="1.0" encoding="UTF-8"?>

<xml_api_reply version="1">
  <weather module_id="0" tab_id="0" mobile_row="0" mobile_zipped="1" row="0" section="0">
    <forecast_information>
      <city data="Hebron, CT"/>
      <postal_code data="06248"/>
      <latitude_e6 data=""/>
      <longitude_e6 data=""/>
      <forecast_date data="2011-02-12"/>
      <current_date_time data="2011-02-13 03:00:47 +0000"/>
      <unit_system data="US"/>
    </forecast_information>
    <current_conditions>
      <condition data="Partly Cloudy"/>
      <temp_f data="28"/>
      <temp_c data="-2"/>
      <humidity data="Humidity: 45%"/>
      <icon data="/ig/images/weather/partly_cloudy.gif"/>
      <wind_condition data="Wind: NW at 14 mph"/>
    </current_conditions>
    <forecast_conditions>
      <day_of_week data="Sat"/>
      <low data="16"/>
      <high data="36"/>
      <icon data="/ig/images/weather/partly_cloudy.gif"/>
      <condition data="Partly Cloudy"/>
    </forecast_conditions>
    <forecast_conditions>
      <day_of_week data="Sun"/>
      <low data="30"/>
      <high data="38"/>
      <icon data="/ig/images/weather/snow.gif"/>
      <condition data="Snow Showers"/>
    </forecast_conditions>
    <forecast_conditions>
      <day_of_week data="Mon"/>
      <low data="23"/>
      <high data="46"/>
      <icon data="/ig/images/weather/cloudy.gif"/>
      <condition data="Cloudy"/>
    </forecast_conditions>
    <forecast_conditions>
      <day_of_week data="Tue"/>
      <low data="12"/>
      <high data="29"/>
      <icon data="/ig/images/weather/cloudy.gif"/>
      <condition data="Windy"/>
    </forecast_conditions>
  </weather>
</xml_api_reply>

Answer 4

我认为您需要打开与 url 的连接并获取输入流以使其正常工作。我会试试这个：

 URL googleWeatherService = null;
 URLConnection conn = null;
try {
    googleWeatherService = new URL(link);
    conn = googleWeatherService.openConnection();
} catch (MalformedURLException e1) {
    // TODO Auto-generated catch block
    e1.printStackTrace();
} 
SAXBuilder parser = new SAXBuilder();
try {
    doc = parser.build(conn.getInputStream());

希望这对你有用！

否则，如果失败，听起来您必须处理 URL 重定向，这是我曾经遇到的问题。在这种情况下，您需要执行以下操作：

 URL googleWeatherService = null;
 URLConnection conn = null;
try {
googleWeatherService = new URL(link);
HttpURLConnection ucon = (HttpURLConnection) googleWeatherService.openConnection();
ucon.setInstanceFollowRedirects(false);
URL secondURL = new URL(ucon.getHeaderField("Location"));
conn = secondURL.openConnection();
} catch (MalformedURLException e1) {
    // TODO Auto-generated catch block
    e1.printStackTrace();
} 
SAXBuilder parser = new SAXBuilder();
try {
    doc = parser.build(conn.getInputStream());

希望这能解决它！