1.構造一個天氣的模型（類）

public class WeatherInfo {
	private String date;//時間
	private String cityname;//城市名
	private String weather;//天氣
	private String temperature;//氣溫
	private String airquality;//pm2.5

	public String getDate() {
		return date;
	}

	public void setDate(String date) {
		this.date = date;
	}

	public String getCityname() {
		return cityname;
	}

	public void setCityname(String cityname) {
		this.cityname = cityname;
	}

	public String getWeather() {
		return weather;
	}

	public void setWeather(String weather) {
		this.weather = weather;
	}

	public String getTemperature() {
		return temperature;
	}

	public void setTemperature(String temperature) {
		this.temperature = temperature;
	}

	public String getAirquality() {
		return airquality;
	}

	public void setAirquality(String airquality) {
		this.airquality = airquality;
	}

	@Override
	public String toString() {
		return "WeatherInfo [date=" + date + ", cityname=" + cityname
				+ ", weather=" + weather + ", temperature=" + temperature
				+ ", airquality=" + airquality + "]";
	}
	
}
 

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLEncoder;
import java.util.zip.GZIPInputStream;

import net.sf.json.JSONArray;
import net.sf.json.JSONObject;

import org.junit.Test;

/**
 * 通過get請求向網站http://wthrcdn.etouch.cn/weather_mini獲取某個 城市的天氣狀況資料，資料格式是Json
 * 
 * @author 22786
 * 
 */
public class WeatherUtils {
	/**
	 * 通過城市名稱獲取該城市的天氣資訊
	 * 
	 * @param cityName
	 * @return
	 */
	
	public  static String GetWeatherData(String cityname) {
		StringBuilder sb=new StringBuilder();;
		try {
			//cityname = URLEncoder.encode(cityName, "UTF-8");
			String weather_url = "http://wthrcdn.etouch.cn/weather_mini?city="+cityname;
			

			URL url = new URL(weather_url);
			URLConnection conn = url.openConnection();
			InputStream is = conn.getInputStream();
			GZIPInputStream gzin = new GZIPInputStream(is);
			InputStreamReader isr = new InputStreamReader(gzin, "utf-8"); // 設定讀取流的編碼格式，自定義編碼
			BufferedReader reader = new BufferedReader(isr);
			String line = null;
			while((line=reader.readLine())!=null)
				sb.append(line+" ");
			reader.close();
		} catch (UnsupportedEncodingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (MalformedURLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		//System.out.println(sb.toString());
		return sb.toString();
		
	}
	
	
	/**
	 * 將JSON格式資料進行解析 ，返回一個weather物件
	 * @param str
	 * @return
	 */
	public static WeatherInfo GetWeather(String weatherInfobyJson){
		JSONObject dataOfJson = JSONObject.fromObject(weatherInfobyJson);
		if(dataOfJson.getInt("status")!=1000)
			return null;
		
		//建立WeatherInfo物件，提取所需的天氣資訊
		WeatherInfo weatherInfo = new WeatherInfo();
		
		//從json資料中提取資料
		String data = dataOfJson.getString("data");
		
		dataOfJson = JSONObject.fromObject(data);
		weatherInfo.setCityname(dataOfJson.getString("city"));;
		weatherInfo.setAirquality(dataOfJson.getString("aqi"));
		
		//獲取預測的天氣預報資訊
		JSONArray forecast = dataOfJson.getJSONArray("forecast");
		//取得當天的
		JSONObject result=forecast.getJSONObject(0);
		
		weatherInfo.setDate(result.getString("date"));
		
		String high = result.getString("high").substring(2);
		String low  = result.getString("low").substring(2);
		
		weatherInfo.setTemperature(low+"~"+high);
		
		weatherInfo.setWeather(result.getString("type"));
		
		
		
		return weatherInfo;
	}
}
 

public class Test {
	public static void main(String[]  args){
		String info = WeatherUtils.GetWeatherData("武漢");
		WeatherInfo weatherinfo = WeatherUtils.GetWeather(info);
		System.out.println(weatherinfo.toString());
	}
}

{"data":{"yesterday":{"date":"20日星期一","high":"高溫 12℃","fx":"無持續風向","low":"低溫 3℃","fl":"","type":"晴"},"city":"武漢","aqi":"105","forecast":[{"date":"21日星期二","high":"高溫 13℃","fengli":"","low":"低溫 6℃","fengxiang":"無持續風向","type":"多雲"},{"date":"22日星期三","high":"高溫 13℃","fengli":"","low":"低溫 4℃","fengxiang":"北風","type":"多雲"},{"date":"23日星期四","high":"高溫 14℃","fengli":"","low":"低溫 3℃","fengxiang":"無持續風向","type":"多雲"},{"date":"24日星期五","high":"高溫 15℃","fengli":"","low":"低溫 3℃","fengxiang":"無持續風向","type":"多雲"},{"date":"25日星期六","high":"高溫 16℃","fengli":"","low":"低溫 4℃","fengxiang":"無持續風向","type":"多雲"}],"ganmao":"天涼，晝夜溫差較大，較易發生感冒，請適當增減衣服，體質較弱的朋友請注意適當防護。","wendu":"10"},"status":1000,"desc":"OK"}

5.通過解析獲得自己所需的資料

WeatherInfo [date=21日星期二, cityname=武漢, weather=多雲, temperature= 6℃~ 13℃, airquality=105]