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Java 实现天气预报功能：从请求到数据解析全解析

一、获取天气预报的方法

在实现天气预报功能时，我们需要通过网络请求获取天气信息。常见的做法是使用 HttpClient 或其他网络库来发送 HTTP 请求，获取目标城市的天气数据。

1. 使用 HttpClient 获取数据

以下是使用 HttpClient 的示例代码：

HttpClient client = new HttpClient();String url = "http://example.com/weather?city=" + URLEncoder.encode(city, "GBK");GetMethod method = new GetMethod(url);int httpstatus = client.executeMethod(method);if (httpstatus == 200) {    // 获取响应内容    String result = method.getResponseBodyAsString();    // 转码为GBK    result = new String(result.getBytes("iso-8859-1"), "GBK");    // 解析响应内容    parseWeatherData(result);}

2. 处理中文编码问题

在发送请求时，城市名需要进行 URL 编码，避免乱码：

String url = "http://example.com/weather?city=" + URLEncoder.encode(city, "GBK");

3. 解析天气数据

天气数据通常以 XML 格式返回。我们需要解析 XML 数据，提取所需的信息，如温度、风速、气压等。

以下是一个简化的解析方法：

public void parseWeatherData(String html) {    // 提取天气信息    String climate = parseWeatherInfo(html, "天气");    String temperature = parseWeatherInfo(html, "气温");    String wind = parseWeatherInfo(html, "风");    String barometric = parseWeatherInfo(html, "气压");        System.out.println("天气：" + climate + "/ 气温 ：" + temperature + "/ 风 " + wind + "/ 气压" + barometric);}

4. 解析方法

以下是一个简单的解析方法：

public String parseWeatherInfo(String str, String word) {    String w = null;    String st = "w365line1";    int a = str.indexOf(st);    if (a != -1) {        String div1 = "
   
    ";        String div2 = "
   
";        String keyword = ":";        int d1 = str.lastIndexOf(div1, a);        int d2 = str.indexOf(div2, a);        if (d2 != -1) {            String str2 = str.substring(d1, d2 + div2.length());            if (str2.indexOf(word) != -1) {                w = filterStr(str2, word, "");                if (w == null) {                    w = filterStr(str2, word, "N/A");                }                return w;            } else {                w = parseWeatherInfo(str.substring(0, d2) + div2, word);            }        }    }    return w;}

5. 数据过滤方法

以下是一个简单的过滤方法：

public String filterStr(String html, String word, String replacement) {    try {        if (replacement == null) {            replacement = "";        }        String str = html;        String str1 = "(<[^>]*>)|( )";        Pattern p = Pattern.compile(str1);        Matcher m = p.matcher(str);        StringBuffer sb = new StringBuffer();        while (m.find()) {            m.appendReplacement(sb, replacement);        }        m.appendTail(sb);        return sb.toString();    } catch (Exception e) {        return html;    }}

二、完整代码实现

以下是完整的 Java 代码实现：

package stwolf.hustbaidu.java.learn.filelist;import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.net.URL;import java.net.URLConnection;import java.util.HashMap;import javax.xml.parsers.DocumentBuilder;import javax.xml.parsers.DocumentBuilderFactory;import javax.xml.transform.Transformer;import javax.xml.transform.TransformerFactory;import javax.xml.transform.dom.DOMSource;import javax.xml.transform.stream.StreamResult;import org.w3c.dom.Document;import org.w3c.dom.NamedNodeMap;import org.w3c.dom.Node;import org.w3c.dom.NodeList;class GetWeatherInfo {    public static HashMap
   
     cityCode = new HashMap
    
     ();    private final String[] dictionaryStrings = {        "龙卷风", "热带风暴", "飓风", "强雷阵雨", "雷阵雨", "小雨加雪", "雨加冰雹",        "雪加冰雹", "冰雨", "毛毛雨", "冻雨", "阵雨", "阵雨", "小雪", "零星小雪",        "高吹雪", "雪", "冰雹", "雨夹雪", "尘", "雾", "薄雾", "多烟的", "大风",        "有风", "寒冷", "阴天", "夜间阴天", "白天阴天", "夜间多云", "白天多云",        "夜间清亮", "晴朗", "转晴", "转晴", "雨夹冰雹", "热", "雷阵雨",        "雷阵雨", "雷阵雨", "雷阵雨", "大雪", "阵雪", "大雪"    };    public GetWeatherInfo() {        initCitys();    }    private void initCitys() {        cityCode.put("北京", "0008");        cityCode.put("天津", "0133");        cityCode.put("武汉", "0138");        cityCode.put("杭州", "0044");        cityCode.put("合肥", "0448");        cityCode.put("上海", "0116");        cityCode.put("福州", "0031");        cityCode.put("重庆", "0017");        cityCode.put("南昌", "0097");        cityCode.put("香港", "0049");        cityCode.put("济南", "0064");        cityCode.put("澳门", "0512");        cityCode.put("郑州", "0165");        cityCode.put("呼和浩特", "0249");        cityCode.put("乌鲁木齐", "0135");        cityCode.put("长沙", "0013");        cityCode.put("银川", "0259");        cityCode.put("广州", "0037");        cityCode.put("拉萨", "0080");        cityCode.put("海口", "0502");        cityCode.put("南京", "0100");        cityCode.put("成都", "0016");        cityCode.put("石家庄", "0122");        cityCode.put("贵阳", "0039");        cityCode.put("太原", "0129");        cityCode.put("昆明", "0076");        cityCode.put("沈阳", "0119");        cityCode.put("西安", "0141");        cityCode.put("长春", "0010");        cityCode.put("兰州", "0079");        cityCode.put("西宁", "0236");    }    private Document getWeatherXML(String cityCode) throws IOException {        URL url = new URL("" + cityCode + "&u=c");        URLConnection connection = url.openConnection();        Document Doc = stringToElement(connection.getInputStream());        return Doc;    }    private void saveXML(Document Doc, String Path) {        TransformerFactory transFactory = TransformerFactory.newInstance();        Transformer transformer;        try {            transformer = transFactory.newTransformer();            DOMSource domSource = new DOMSource(Doc);            File file = new File(Path);            FileOutputStream out = new FileOutputStream(file);            StreamResult xmlResult = new StreamResult(out);            transformer.transform(domSource, xmlResult);        } catch (Exception e) {            System.out.println("保存文件出错！");        }    }    public String getWeather(String city) {        String result = null;        try {            Document doc = getWeatherXML(GetWeatherInfo.cityCode.get(city));            NodeList nodeList = doc.getElementsByTagName("channel");            for (int i = 0; i < nodeList.getLength(); i++) {                Node node = nodeList.item(i);                NodeList nodeList1 = node.getChildNodes();                for (int j = 0; j < nodeList1.getLength(); j++) {                    Node node1 = nodeList1.item(j);                    if (node1.getNodeName().equalsIgnoreCase("item")) {                        NodeList nodeList2 = node1.getChildNodes();                        for (int k = 0; k < nodeList2.getLength(); k++) {                            Node node2 = nodeList2.item(k);                            if (node2.getNodeName().equalsIgnoreCase("yweather:forecast")) {                                NamedNodeMap nodeMap = node2.getAttributes();                                Node lowNode = nodeMap.getNamedItem("low");                                Node highNode = nodeMap.getNamedItem("high");                                Node codeNode = nodeMap.getNamedItem("code");                                String day = "今天";                                if (result == null) {                                    result = "";                                } else {                                    day = "明天";                                }                                result = result + day + " 最低温度：" + lowNode.getNodeValue() + "℃ 最高温度：" + highNode.getNodeValue() + "℃";                            }                        }                    }                }            }            saveXML(doc, "C:/Users/ygui/Desktop/Weather.xml");        } catch (Exception e) {            e.printStackTrace();        }        return result;    }    public Document stringToElement(InputStream input) {        try {            DocumentBuilder db = DocumentBuilderFactory.newInstance().newDocumentBuilder();            Document doc = db.parse(input);            return doc;        } catch (Exception e) {            return null;        }    }    public static void main(String[] args) throws Exception {        GetWeatherInfo info = new GetWeatherInfo();        String weather = info.getWeather("武汉");        System.out.println(weather);    }}
    
   

三、常见问题与解决方案

四、总结

通过以上方法，我们可以实现从网络请求到数据解析的完整流程，获取所需的天气预报信息。该方法基于标准的 XML 数据格式，结合 HttpClient 和 XML 解析技术，能够灵活适应不同天气服务提供商的 API 接口。

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