使用GSON获取天气预报信息

gson可能大部分程序员都不熟悉，简言之就是一个json工具，可实现对象和json字符串之间的转换；有人可能会说了用json-lib就可以了啊，之前我也是用json-lib的但是总是觉得很麻烦，生成json还OK但是解析就要费九牛二虎之力了，权衡之下还是选择使用gson.这次就使用gson配合百度API来实现天气预报的查询功能。

一  gson的下载地址

Gson是Google提供的用于在Java对象和JSON字符串之间进行转换的Java类库。

下载地址1：https://code.google.com/p/google-gson/downloads/list
下载地址2：http://download.csdn.net/detail/lyq8479/8451103

二  代码实现

1 先来体验下gson的简单使用

先搞个pojo类：

package org.lxh;

public class UserInfo {
	private String name;
	private String address;
	private String email;

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getAddress() {
		return address;
	}

	public void setAddress(String address) {
		this.address = address;
	}

	public String getEmail() {
		return email;
	}

	public void setEmail(String email) {
		this.email = email;
	}
}

接下来直接上测试类：

package org.lxh;

import java.util.ArrayList;
import java.util.List;

import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;

public class UseGson {
  public static void main(String args[]){
	  
	  UserInfo u1=new UserInfo();
	  u1.setAddress("上海浦东新区");
	  u1.setEmail("[email protected]");
	  u1.setName("王大锤");
	  
	  Gson gson=new Gson();
	  String jsonStr=gson.toJson(u1);
	  
	  System.out.println(jsonStr);
	 
	  
	  UserInfo u2=new UserInfo();
	  u2.setAddress("安徽芜湖");
	  u2.setEmail("[email protected]");
	  u2.setName("蜡笔小新");
	  
	  List all=new ArrayList();
	  all.add(u1);
	  all.add(u2);
	  
	  String jsonArrStr=gson.toJson(all);
	  
	  System.out.println("------------------生成json数组-------------------");
	  System.out.println(jsonArrStr);
	  System.out.println("------------------把JSON转成对象-------------------");
	  List obj=gson.fromJson(jsonArrStr, new TypeToken>(){}.getType());
	  System.out.println(obj.get(0).getAddress());
	  
  }
}

来看下运行效果：

2  封装天气预报工具类

百度API地址：http://developer.baidu.com/map/index.php?title=car/api/weather

使用之前要先注册个开发者账号，之后创建应用就能得到ak了，这些操作就自己搞了，你们都懂的。

（1）封装WeatherData类

 

package org.lxh;

public class WeatherData {
	private String date;
	private String weather;
	private String dayPictureUrl;
	private String nightPictureUrl;
	private String wind;
	private String temperature;

	public String getDate() {
		return date;
	}

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

	public String getDayPictureUrl() {
		return dayPictureUrl;
	}

	public void setDayPictureUrl(String dayPictureUrl) {
		this.dayPictureUrl = dayPictureUrl;
	}

	public String getNightPictureUrl() {
		return nightPictureUrl;
	}

	public void setNightPictureUrl(String nightPictureUrl) {
		this.nightPictureUrl = nightPictureUrl;
	}

	public String getWind() {
		return wind;
	}

	public void setWind(String wind) {
		this.wind = wind;
	}

	public String getTemperature() {
		return temperature;
	}

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

	public String getWeather() {
		return weather;
	}

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

（2）封装WeatherResult

package org.lxh;

import java.util.List;

public class WeatherResult {
	private String currentCity;
	private String pm25;
	private List weather_data;

	public String getCurrentCity() {
		return currentCity;
	}

	public void setCurrentCity(String currentCity) {
		this.currentCity = currentCity;
	}

	public String getPm25() {
		return pm25;
	}

	public void setPm25(String pm25) {
		this.pm25 = pm25;
	}

	public List getWeather_data() {
		return weather_data;
	}

	public void setWeather_data(List weatherData) {
		weather_data = weatherData;
	}
}

（3）封装WeatherResp

 

package org.lxh;

import java.util.List;

public class WeatherResp {
	private int error;
	private String status;
	private String date;
	private List results;

	public int getError() {
		return error;
	}

	public void setError(int error) {
		this.error = error;
	}

	public String getStatus() {
		return status;
	}

	public void setStatus(String status) {
		this.status = status;
	}

	public String getDate() {
		return date;
	}

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

	public List getResults() {
		return results;
	}

	public void setResults(List results) {
		this.results = results;
	}
}

（4）HttpURLConnection操作工具类

package org.lxh;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.ConnectException;
import java.net.HttpURLConnection;
import java.net.URL;



public class CommonUtil {
	  public static String httpRequest(String requestUrl, String requestMethod, String outputStr) {  
	       
	        StringBuffer buffer = new StringBuffer();  
	        try {  
	 
	            URL url = new URL(requestUrl);  
	            HttpURLConnection httpUrlConn = (HttpURLConnection) url.openConnection();  
	            httpUrlConn.setDoOutput(true);  
	            httpUrlConn.setDoInput(true);  
	            httpUrlConn.setUseCaches(false);  
	            // 设置请求方式（GET/POST）  
	            httpUrlConn.setRequestMethod(requestMethod);  
	            httpUrlConn.connect();  
	           
	            // 当有数据需要提交时  
	            if (null != outputStr) {  
	                OutputStream outputStream = httpUrlConn.getOutputStream();  
	                // 注意编码格式，防止中文乱码  
	                outputStream.write(outputStr.getBytes("UTF-8"));  
	                outputStream.close();  
	            }  
	  
	            // 将返回的输入流转换成字符串  
	            InputStream inputStream = httpUrlConn.getInputStream();  
	            InputStreamReader inputStreamReader = new InputStreamReader(inputStream, "utf-8");  
	            BufferedReader bufferedReader = new BufferedReader(inputStreamReader);  
	  
	            String str = null;  
	            while ((str = bufferedReader.readLine()) != null) {  
	                buffer.append(str);  
	            }  
	            bufferedReader.close();  
	            inputStreamReader.close();  
	            // 释放资源  
	            inputStream.close();  
	            inputStream = null;  
	           
	        } catch (ConnectException ce) {  
	        	ce.printStackTrace();
	          
	        } catch (Exception e) {  
	          
	        	e.printStackTrace();
	        }  
	        return buffer.toString();  
	    }  
}

（5）天气预报获取工具类

package org.lxh;

import java.net.URLEncoder;
import java.util.Iterator;
import java.util.List;

import com.google.gson.Gson;

public class WeatherUtil {
   public static String getWeatherResult(String cityName) throws Exception{
	   
	   String requestUrl="http://api.map.baidu.com/telematics/v3/weather?location={LOCATION}&output=json&ak={KEY}";
	   String requestWeatherUrl=requestUrl.replace("{LOCATION}", URLEncoder.encode(cityName, "UTF-8")).replace("{KEY}", "你的AK");
	   
	   String result=CommonUtil.httpRequest(requestWeatherUrl, "POST", null);
	   //System.out.println(result);
	   Gson gson=new Gson();
	   WeatherResp wresp=gson.fromJson(result, WeatherResp.class);
	   
	   StringBuffer buf=new StringBuffer();
	   buf.append(cityName+"天气预报"+"\n\n");
	   
	   List wdata=wresp.getResults().get(0).getWeather_data();
	   Iterator it=wdata.iterator();
	   while(it.hasNext()){
		   WeatherData w=it.next();
		   buf.append(w.getDate()+","+w.getWeather()+","+w.getTemperature()+","+w.getWind());
		   buf.append("\n\n");
	   }
	   return buf.toString();
   }
   
   public static void main(String args[]) throws Exception{
	   System.out.println(getWeatherResult("苏州"));
   }
}

来看下运行效果截图：

天气预报的接口来源还是挺多的，数据交互方式也不尽相同，选择合适的就行，不一定局限于百度的API.gson的使用关键在于json数据的分析，按结构提取出合适的pojo类能很好的降低解析难度。