天气预报代码分析与实现

在做网站中，遇到天气预报接口是避免不了的，天气预报的实现主要涉及到以下几个技术点：

1. 正则表达式匹配从中央气象局的天气预报网页，这种方式下，固定城市实现比较简单，不同城市需要一个对照表，来完成这个映射工作
2. IP识别获取城市（本文实现方式）
3. 利用WebService服务接口获取城市天气（本文实现方式）
4. 已拉取的城市天气当日缓存（本文实现方式）

附效果地址：http://weather.faqee.com/ 

 

定义缓存：

private static HashMap<String,JSONObject> hmCache = new HashMap();

 

缓存通过TimerTask定时清空前几天实现，代码如下：

    public static void cleanCache() { 
    	if(isStart) return;
    	isStart = true;
        TimerTask task = new TimerTask() { 
            public void run() {        
            	Iterator it = hmCache.entrySet().iterator();
            	while (it.hasNext()) {
            		Map.Entry entry = (Map.Entry) it.next();
            		Object key = entry.getKey(); 
            		String today = DateTimeUtil.format(new Date(),"yyyyMMdd");
            		if(key.toString().indexOf(today)>=0){
            			it.remove();
            			hmCache.remove(key);
            		}  		
            	}           	
            } 
        }; 
        Timer timer = new Timer(); 
        timer.schedule(task, Calendar.getInstance ().getTime(), 24*3600 * 1000); 

     } 

 拉取天气：

    public JSONObject getWeather(String city) {  
    	String today = DateTimeUtil.format(new Date(),"yyyyMMdd");
    	if(hmCache.get(city+today)!=null){
    		return hmCache.get(city+today);
    	}
    	JSONObject hm =new JSONObject();
		hm.put("zhishu","");

        try {    
        	city = getCityName(city);
            Document doc;    
            DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();    
            dbf.setNamespaceAware(true);    
            DocumentBuilder db = dbf.newDocumentBuilder();    
            InputStream is = getSoapInputStream(city);  
            if(is == null) return hm;
            doc = db.parse(is);    
            NodeList nl = doc.getElementsByTagName("Date");    
            
            String tpPrefix = "http://www.nmc.gov.cn/img/weather/dn_icon/";
            String t = "",t_res = "",t_tp="";
            String t1 = "",t1_res = "",t1_tp="";
            String t2 = "",t2_res = "",t2_tp="";
            String t3 = "",t3_res = "",t3_tp="";
            
            for (int count = 0; count < nl.getLength(); count++) {    
                Node n = nl.item(count);    
                
                NodeList n2 = n.getChildNodes();

                
                t = doc.getElementsByTagName("Sj0").item(0).getFirstChild().getNodeValue(); 
                t1 = doc.getElementsByTagName("Sj1").item(0).getFirstChild().getNodeValue(); 
                t2 = doc.getElementsByTagName("Sj2").item(0).getFirstChild().getNodeValue(); 
                t3 = doc.getElementsByTagName("Sj3").item(0).getFirstChild().getNodeValue(); 
                
                if(n2!=null){
                	for(int jj=0;jj<n2.getLength();jj++){
                		Node nn = n2.item(jj);
                		if(count == 0 ) // 今天
                		{
                			if(nn.getNodeName().equalsIgnoreCase("tq")){
                				t_res += nn.getFirstChild().getNodeValue();
                			}else if(nn.getNodeName().equalsIgnoreCase("Qw")){
                				t_res += ","+nn.getFirstChild().getNodeValue();
                			}else if(nn.getNodeName().equalsIgnoreCase("Fx")){
                				t_res += ","+nn.getFirstChild().getNodeValue();
                			}else if(nn.getNodeName().equalsIgnoreCase("Rc")){
                				t_res += ","+nn.getFirstChild().getNodeValue();
                			}else if(nn.getNodeName().equalsIgnoreCase("Rl")){
                				t_res += ","+nn.getFirstChild().getNodeValue();
                			}else if(nn.getNodeName().equalsIgnoreCase("TP")){
                				t_tp = nn.getFirstChild().getNodeValue();
                				t_tp = Utils.replace(t_tp,"\"","");
                				t_tp = Utils.replace(t_tp,"/images/","");
                				t_tp = tpPrefix + t_tp;
                			}
                		}else if(count == 1) //明天
                		{
                			if(nn.getNodeName().equalsIgnoreCase("tq")){
                				t1_res += nn.getFirstChild().getNodeValue();
                			}else if(nn.getNodeName().equalsIgnoreCase("Qw")){
                				t1_res += ","+nn.getFirstChild().getNodeValue();
                			}else if(nn.getNodeName().equalsIgnoreCase("Fx")){
                				t1_res += ","+nn.getFirstChild().getNodeValue();
                			} else if(nn.getNodeName().equalsIgnoreCase("TP")){
                				t1_tp = nn.getFirstChild().getNodeValue();
                				t1_tp = Utils.replace(t1_tp,"\"","");
                				t1_tp = Utils.replace(t1_tp,"/images/","");
                				t1_tp = tpPrefix + t1_tp;
                			}              			
                		}else if(count == 2) //后天
                		{
                			if(nn.getNodeName().equalsIgnoreCase("tq")){
                				t2_res += nn.getFirstChild().getNodeValue();
                			}else if(nn.getNodeName().equalsIgnoreCase("Qw")){
                				t2_res += ","+nn.getFirstChild().getNodeValue();
                			}else if(nn.getNodeName().equalsIgnoreCase("Fx")){
                				t2_res += ","+nn.getFirstChild().getNodeValue();
                			}else if(nn.getNodeName().equalsIgnoreCase("TP")){
                				t2_tp = nn.getFirstChild().getNodeValue();
                				t2_tp = Utils.replace(t2_tp,"\"","");
                				t2_tp = Utils.replace(t2_tp,"/images/","");
                				t2_tp = tpPrefix + t2_tp;
                			}  
                		}else if(count == 3) //大后天
                		{
                			if(nn.getNodeName().equalsIgnoreCase("tq")){
                				t3_res += nn.getFirstChild().getNodeValue();
                			}else if(nn.getNodeName().equalsIgnoreCase("Qw")){
                				t3_res += ","+nn.getFirstChild().getNodeValue();
                			}else if(nn.getNodeName().equalsIgnoreCase("Fx")){
                				t3_res += ","+nn.getFirstChild().getNodeValue();
                			}else if(nn.getNodeName().equalsIgnoreCase("TP")){
                				t3_tp = nn.getFirstChild().getNodeValue();
                				t3_tp = Utils.replace(t3_tp,"\"","");
                				t3_tp = Utils.replace(t3_tp,"/images/","");
                				t3_tp = tpPrefix + t3_tp;
                			}  
                		}
                			
                		
                	}
                }
                

              
            }    
            is.close();    
            hm.put("t", t);
            hm.put("t_result", t_res);
            hm.put("t_tp", t_tp.trim());
            hm.put("t1", t1);
            hm.put("t1_result", t1_res);
            hm.put("t1_tp", t1_tp.trim());
            hm.put("t2", t2);
            hm.put("t2_result", t2_res);
            hm.put("t2_tp", t2_tp.trim());
            hm.put("t3", t3);
            hm.put("t3_result", t3_res);
            hm.put("t3_tp", t3_tp.trim());
            
            hmCache.put(city+today, hm);
            
            return hm;
        } catch (Exception e) {    
            e.printStackTrace();    
            return null;    
        }    
    }  

 

附效果地址：http://weather.faqee.com/