如何从网页上获取城市天气信息？

编写一段Java代码，从如下网站http://www.weather.com.cn/ 获得西安的天气信息：
Java代码  
package com.url;  
  
import java.io.BufferedReader;  
import java.io.IOException;  
import java.io.InputStreamReader;  
import java.net.URL;  
import java.util.ArrayList;  
import java.util.List;  
import java.util.regex.Matcher;  
import java.util.regex.Pattern;  
  
public class Weather {  
  
    public static void main(String[] args) {  
  
        String weatherReturn = getWeatherInfo();  
  
        //获得层div  
        Pattern pattern = Pattern  
                .compile("<div class=\"weatherYubaoBox\">.*?</div>");  
  
        Matcher matcher = pattern.matcher(weatherReturn);  
  
        String weatherTable = "";  
  
        if (matcher.find()) {  
            weatherTable = matcher.group();  
        }  
  
        //找表  
        String weatherToday = "";  
          
        if (!weatherTable.equals("") && weatherTable.length() > 0) {  
              
            pattern = Pattern  
                    .compile("<table class=\"yuBaoTable\".*?>.*?</table>");  
            matcher = pattern.matcher(weatherTable);  
              
            if (matcher.find()) {  
                weatherToday = matcher.group();  
            }  
        }  
  
        pattern = Pattern.compile("<a.*?</a>");  
          
        matcher = pattern.matcher(weatherToday);  
          
        List<String> weatherList = new ArrayList<String>();  
        while (matcher.find()) {  
              
            weatherList.add(matcher.group());  
            System.out.println(replaceTagA(matcher.group()));  
              
        }  
    }  
  
    // 获取网页上的内容  
    public static String getWeatherInfo() {  
  
        URL url = null;  
        InputStreamReader inReader = null;  
        BufferedReader reader = null;  
          
        try {  
  
            // 建立一个url  
            url = new URL("http://www.weather.com.cn/weather/101110101.shtml");  
  
            // 打开一个流,并设置编码格式  
            inReader = new InputStreamReader(url.openStream(), "utf-8");  
            reader = new BufferedReader(inReader);  
  
            StringBuffer sb = new StringBuffer();  
  
            String inputLine;  
  
            while ((inputLine = reader.readLine()) != null) {  
                sb.append(inputLine);  
            }  
              
            return sb.toString();  
        } catch (Exception e) {  
  
            e.printStackTrace();  
              
        } finally {  
            // 关闭流  
            if (reader != null) {  
                try {  
                    reader.close();  
                } catch (IOException e) {  
                    e.printStackTrace();  
                }  
            }  
            if (inReader != null) {  
                try {  
                    inReader.close();  
                } catch (IOException e) {  
                    e.printStackTrace();  
                }  
            }  
        }  
        return null;  
    }  
  
    //从超连接中取数据  
    public static String replaceTagA(String orginal) {  
          
        List<String> resultList = new ArrayList<String>();  
          
        if (orginal != null && !"".equals(orginal)) {  
  
            Pattern pattern = Pattern.compile(">.*?<");  
            Matcher matcher = pattern.matcher(orginal);  
            while (matcher.find()) {  
                String temp = matcher.group();  
                temp = temp.replace('>', ' ');  
                temp = temp.replace('<', ' ');  
                resultList.add(temp.trim());  
            }  
        }  
        StringBuffer result = new StringBuffer();  
        for (String temp : resultList) {  
            result.append(temp);  
        }  
        return result.toString().trim();  
    }  
}  
public class WeatherJob implements Job{    // 代表自动获取天气预报    private static final String AUTOMATIC = "0";        private IWeatherService weatherService;        public WeatherJob()    {        weatherService = (IWeatherService)PortalMSBeanFactory.getInstance()                .getBean("portalWeatherService");    }        private static final DebugLogHelper logger = new DebugLogHelper(WeatherJob.class);    private  List<Weather> WeatherLists = new ArrayList<Weather>();        /**     * 执行定时任务     */    @SuppressWarnings("unchecked")    public void execute(JobExecutionContext context)    {        logger.enterFuncDebugLog();        String type = XMLFactory.getValueString("weather.type");        if (AUTOMATIC.equals(type))        {            logger.enterFuncDebugLog("======================Begin WeatherTaskManager.execute()======================");            List<WeatherImage> imageList = new ArrayList<WeatherImage>();                        DefaultHttpClient httpclient = new DefaultHttpClient();            String url = XMLFactory.getValueString("weather.weatherUrl");            HttpGet httpget = new HttpGet(url);            try            {                logger.atFuncDebugLog();                HttpResponse response = httpclient.execute(httpget);                                HttpEntity entity = response.getEntity();                if (entity != null)                {                    WeatherInfo weather = new WeatherInfo();                                        InputStream in = entity.getContent();                                        int count = 0;                    while (count == 0)                    {                        count = Integer.parseInt("" + entity.getContentLength());                    }                    byte[] bytes = new byte[count];                                        // 已经成功读取的字节的个数                    int readCount = 0;                    while (readCount <= count)                    {                        if (readCount == count)                            break;                        readCount += in.read(bytes, readCount, count                                - readCount);                    }                                        // 转换成字符串                    String readContent = new String(bytes, 0, readCount,                            "UTF-8");                                        Document document = DocumentHelper.parseText(readContent);                                        Element root = document.getRootElement();                                        // 获取根节点下的子节点active                    Element data = root.element("data");                                        // 天气信息                    String report = data.elementText("report");                                        String weatherInfo[] = report.split("；");                                        weather.setWeatherDesc(weatherInfo[0]);                    weather.setTemperature(weatherInfo[1].replace(ChineseCharacter.WEATHERJOB_TEMPERATURE,                            ""));                    weather.setType(0);                    weather.setUpdater(1L);                                        // 天气信息                    String dateStr = data.elementText("date");                    weather.setWeatherDate(dateStr);                                        List<?> fieldList = root.selectNodes("/root/data/weathericons/icon");                                        String suffix = Constants.SPLIT_DOT.getStringValue()                            + XMLFactory.getValueString("weather.imageSuffix");                    for (int i = 0; i < fieldList.size(); i++)                    {                        WeatherImage image = new WeatherImage();                        Element fieldEle = (Element)fieldList.get(i);                        image.setImage(fieldEle.getStringValue() + suffix);                        imageList.add(image);                    }                                        weather.setWeatherImageList(imageList);                                        try                    {                        weatherService.saveEntity(weather);                    }                    catch (PortalMSException e)                    {                        logger.excepFuncDebugLog("insert the weather is failed:", e);                    }                }            }            catch (ClientProtocolException e1)            {                logger.excepFuncDebugLog("query the weather is failed:", e1);            }            catch (IOException e1)            {                logger.excepFuncDebugLog("query the weather is failed:", e1);            }            catch (Exception e1)            {                logger.excepFuncDebugLog("query the weather is failed:", e1);            }                        logger.exitFuncDebugLog("======================WeatherTaskManager execute() Task End!======================");        }                 //                   WeatherLists = XMLFactory.getValueList("weathers.weather");                List<WeatherInfo> WeatherList = new ArrayList<WeatherInfo>();                try {                    WeatherList = weatherService.findWeatherConfig();                } catch (PortalMSException e) {                    // TODO Auto-generated catch block                    e.printStackTrace();                }                                for (int j = 0; j < WeatherList.size(); j++)                 {                    WeatherInfo weatherinfo = new WeatherInfo();                    weatherinfo = WeatherList.get(j);                                        String weatherReturn = getWeatherInfo(weatherinfo.getWeatherUrl());                    // 获得table                    Pattern pattern = Pattern.compile("<table class=\"FcstBoxTable01\".*?>.*?</table>");                    Matcher matcher = pattern.matcher(weatherReturn);                    String weatherTable = "";                    if (matcher.find())                     {                        weatherTable = matcher.group();                    }                    // 找表                    String weatherToday = "";                    if (!weatherTable.equals("") && weatherTable.length() > 0)                     {                        pattern = Pattern.compile("<tbody>.*?</tbody>");                        matcher = pattern.matcher(weatherTable);                        if (matcher.find())                         {                            weatherToday = matcher.group();                        }                    }                    /**                                          * weather_id NUMBER(13) not null, city_code VARCHAR2(50), city_name                     * VARCHAR2(50) not null, weather_code VARCHAR2(50), weather_desc                     * VARCHAR2(100), temperature VARCHAR2(10), weather_date                     * VARCHAR2(20) not null, image VARCHAR2(512), update_date DATE,                     * type VARCHAR2(10)                     */                    // 获取今天的数据                    String str = weatherToday.substring(                            weatherToday.indexOf("<tr>", 1), weatherToday.indexOf(                                    "</tr>", 1));                    String temperature = str.substring(str.indexOf("<td>", 1) + 4, str                            .indexOf("</td>", 1))+"℃";                    // 天气情况                    pattern = Pattern.compile("alt=\".*?\"");                    matcher = pattern.matcher(str);                    String weather_desc = "";                    if (matcher.find())                     {                        weather_desc = matcher.group();                    }                    weather_desc = weather_desc.substring(5, weather_desc.indexOf("\"",5));                    // 天气预报图片                                        if(str.indexOf("day")>0)                    {                        pattern = Pattern.compile("day/.*?\"");                    }                    else pattern = Pattern.compile("night/.*?\"");                                        matcher = pattern.matcher(str);                    String weather_pic = "";                    if (matcher.find()) {                        weather_pic = matcher.group();                    }                    if(str.indexOf("day")>0)                    {                        weather_pic = weather_pic.substring(4, weather_pic.indexOf("\"", 4));                    }                    else                    {                        weather_pic = weather_pic.substring(6, weather_pic.indexOf("\"", 4));                    }                    weatherinfo.setTemperature(temperature);                    String day = DateUtil.fmtDate(new Date());                    weatherinfo.setWeatherDate(day);                    weatherinfo.setWeatherDesc(weather_desc);                    weatherinfo.setImageUrl(weather_pic);                    weatherinfo.setWeatherId(System.currentTimeMillis());                                                             //新增天气情况同步给portal                   syncWeatherInformation(Constants.SYNC_WEATHERINFO.getStringValue(), weatherinfo);                                                                            }                           }    //获取网页上的内容    public static String getWeatherInfo(String weatherUrl)     {            URL url = null;        InputStreamReader inReader = null;        BufferedReader reader = null;            try {                // 建立一个url            url = new URL(weatherUrl);    //                "http://www.cwb.gov.tw/V7/forecast/taiwan/New_Taipei_City.htm");            // URL("http://www.weather.com.cn/weather/101110101.shtml");                // 打开一个流,并设置编码格式            inReader = new InputStreamReader(url.openStream(), "utf-8");            reader = new BufferedReader(inReader);                StringBuffer sb = new StringBuffer();                String inputLine;                while ((inputLine = reader.readLine()) != null)             {                sb.append(inputLine);            }                return sb.toString();        } catch (Exception e)         {                e.printStackTrace();            } finally         {            // 关闭流            if (reader != null)             {                try {                    reader.close();                } catch (IOException e)                 {                    e.printStackTrace();                }            }            if (inReader != null)             {                try {                    inReader.close();                } catch (IOException e)                 {                    e.printStackTrace();                }            }        }        return null;    }    // 从超连接中取数据    public static String replaceTagA(String orginal) {            List<String> resultList = new ArrayList<String>();            if (orginal != null && !"".equals(orginal)) {                Pattern pattern = Pattern.compile(">.*?<");            Matcher matcher = pattern.matcher(orginal);            while (matcher.find()) {                String temp = matcher.group();                temp = temp.replace('>', ' ');                temp = temp.replace('<', ' ');                resultList.add(temp.trim());            }        }        StringBuffer result = new StringBuffer();        for (String temp : resultList) {            result.append(temp);        }        return result.toString().trim();    }        public IWeatherService getWeatherService()    {        return weatherService;    }        public void setWeatherService(IWeatherService weatherService)    {        this.weatherService = weatherService;    }            public void syncWeatherInformation(String opCode, WeatherInfo weather)    {        logger.enterFuncDebugLog();        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");        String updateDate = "";        if (weather.getWeatherDate() != null)        {            updateDate = weather.getWeatherDate();        }        IMessageSync messageSync = new MessageSync();        SyncWeatherInfoReqBody body = new SyncWeatherInfoReqBody();        WeatherInfoReqMsg weatherInfoReqMsg = new WeatherInfoReqMsg();        weatherInfoReqMsg.setCityCode(weather.getCityCode() == null ? "" : weather.getCityCode());        weatherInfoReqMsg.setCityName(weather.getCityName());        weatherInfoReqMsg.setImage(weather.getImageUrl()== null ? "" : weather.getImageUrl());        weatherInfoReqMsg.setTemperature(weather.getTemperature() == null ? "" : weather.getTemperature());        weatherInfoReqMsg.setUpdateDate(updateDate);        weatherInfoReqMsg.setWeatherID(String.valueOf(weather.getWeatherId()));        body.setWeatherInfo(weatherInfoReqMsg);        messageSync.syncMessage(body, opCode);        logger.exitFuncDebugLog();    }} 
http://www.szmb.gov.cn/data_cache/szWeather/szweather2.1.xml