JSON之三：获取JSON文本并解释（以google的天气API为例）

google提供了天气的api，以广州天气为例，地址为：

http://api.openweathermap.org/data/2.5/weather?q=guangzhou

返回的结果为：

{

    "coord": {

        "lon": 113.25,

        "lat": 23.12

    },

    "sys": {

        "message": 0.2088,

        "country": "CN",

        "sunrise": 1400017567,

        "sunset": 1400065233

    },

    "weather": [

        {

            "id": 501,

            "main": "Rain",

            "description": "moderate rain",

            "icon": "10d"

        }

    ],

    "base": "cmc stations",

    "main": {

        "temp": 299.818,

        "temp_min": 299.818,

        "temp_max": 299.818,

        "pressure": 1004.54,

        "sea_level": 1014.72,

        "grnd_level": 1004.54,

        "humidity": 97

    },

    "wind": {

        "speed": 4.42,

        "deg": 201.501

    },

    "rain": {

        "3h": 6

    },

    "clouds": {

        "all": 44

    },

    "dt": 1400055192,

    "id": 1809858,

    "name": "Guangzhou",

    "cod": 200

}

因此，在本范例中，写一个天气查询的DEMO，用于输入地点，并查询天气情况。

项目更新请见：https://code.csdn.net/jediael_lu/googleweatherparse/tree/master

效果如下：

详细步骤如下：

1、主界面布局文件

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:paddingBottom="@dimen/activity_vertical_margin"
   android:paddingLeft="@dimen/activity_horizontal_margin"
   android:paddingRight="@dimen/activity_horizontal_margin"
   android:paddingTop="@dimen/activity_vertical_margin"
   tools:context=".MainActivity" >

   <TextView
      android:id="@+id/textView1"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_alignParentLeft="true"
      android:layout_alignParentTop="true"
      android:layout_marginTop="15dp"
      android:text="@string/location"
      android:textAppearance="?android:attr/textAppearanceMedium" />

   <EditText
      android:id="@+id/editText1"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_alignBottom="@+id/textView1"
      android:layout_alignParentRight="true"
      android:ems="10" />

   <TextView
      android:id="@+id/textView2"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_alignLeft="@+id/textView1"
      android:layout_below="@+id/textView1"
      android:layout_marginTop="68dp"
      android:text="@string/country"
      android:textAppearance="?android:attr/textAppearanceSmall" />

   <TextView
      android:id="@+id/textView3"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_below="@+id/textView2"
      android:layout_marginTop="19dp"
      android:text="@string/temperature"
      android:textAppearance="?android:attr/textAppearanceSmall" />

   <TextView
      android:id="@+id/textView4"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_alignLeft="@+id/textView3"
      android:layout_below="@+id/textView3"
      android:layout_marginTop="32dp"
      android:text="@string/humidity"
      android:textAppearance="?android:attr/textAppearanceSmall" />

   <TextView
      android:id="@+id/textView5"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_alignLeft="@+id/textView4"
      android:layout_below="@+id/textView4"
      android:layout_marginTop="21dp"
      android:text="@string/pressure"
      android:textAppearance="?android:attr/textAppearanceSmall" />

   <EditText
      android:id="@+id/editText2"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_above="@+id/textView3"
      android:layout_toRightOf="@+id/textView3"
      android:ems="10" >

      <requestFocus />
   </EditText>

   <EditText
      android:id="@+id/editText3"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_alignBaseline="@+id/textView3"
      android:layout_alignBottom="@+id/textView3"
      android:layout_alignLeft="@+id/editText2"
      android:ems="10" />

   <EditText
      android:id="@+id/editText4"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_above="@+id/textView5"
      android:layout_alignLeft="@+id/editText1"
      android:ems="10" />

   <EditText
      android:id="@+id/editText5"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_alignBaseline="@+id/textView5"
      android:layout_alignBottom="@+id/textView5"
      android:layout_alignRight="@+id/editText4"
      android:ems="10" />

   <Button
      android:id="@+id/button1"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_alignLeft="@+id/editText2"
      android:layout_below="@+id/editText1"
      android:onClick="open"
      android:text="@string/weather" />

</RelativeLayout>

2、定义String.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
   <string name="app_name">JSONParser</string>
   <string name="action_settings">Settings</string>
   <string name="hello_world">Hello world!</string>
   <string name="location">Location</string>
   <string name="country">Country:</string>
   <string name="temperature">Temperature:</string>
   <string name="humidity">Humidity:</string>
   <string name="pressure">Pressure:</string>
   <string name="weather">Weather</string>
</resources>

3、在AndroidManifest.xml中添加internet访问权限。

4、创建一个bean，用于保存天气信息。

package com.example.jsonparser.model;

public class WeatherBean {

	private String country;
	private int Temperature;
	private int humidity;
	private int pressure;
	public String getCountry() {
		return country;
	}
	public void setCountry(String country) {
		this.country = country;
	}
	public int getTemperature() {
		return Temperature;
	}
	public void setTemperature(int temperature) {
		Temperature = temperature;
	}
	public int getHumidity() {
		return humidity;
	}
	public void setHumidity(int humidity) {
		this.humidity = humidity;
	}
	public int getPressure() {
		return pressure;
	}
	public void setPressure(int pressure) {
		this.pressure = pressure;
	}

}

5、创建用于访问网络的类，并返回JSON文本。

package com.example.jsonparser;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class JSONFetcher {

	private String jsonText = "";

	//本方法通过指定url访问网络数据，并返回JSON格式的string。
	public  String getJSONText(final URL url){

		Thread thread = new Thread(new Runnable(){

			@Override
			public void run() {
				InputStream is =null;
				BufferedReader in = null;

				try {
					HttpURLConnection conn = (HttpURLConnection) url.openConnection();
					conn.setReadTimeout(10000 /* milliseconds */);
					conn.setConnectTimeout(15000 /* milliseconds */);
					conn.setRequestMethod("GET");
					conn.setDoInput(true);
					conn.connect();

					is = conn.getInputStream();
					in = new BufferedReader(new InputStreamReader(is));
					String line = "";
					while((line = in.readLine()) != null){
						jsonText += line;
					}

				} catch (IOException e) {
					e.printStackTrace();
				}finally{
					try {
						in.close();
						is.close();
					} catch (IOException e) {
						e.printStackTrace();
					}

				}

			}

		});

		thread.start();	

		//等待上述线程完成执行后再返回jsonText。
		try {
			Thread.sleep(1000);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}

		return jsonText;
	}

}

6、创建用于处理JSON文本的类，返回一个WeatherBean对象。

package com.example.jsonparser;

import java.net.URL;

import org.json.JSONException;
import org.json.JSONObject;

import com.example.jsonparser.model.WeatherBean;

public class JSONUtil {

	public static WeatherBean getWeatherBean(URL url){

		String jsonText = new JSONFetcher().getJSONText(url);
		System.out.println(jsonText);
		WeatherBean weather = new WeatherBean();

		try {
			JSONObject weatherJSONObject = new JSONObject(jsonText);

			JSONObject sysJSONObject = weatherJSONObject.getJSONObject("sys");
			String country = sysJSONObject.getString("country");
			JSONObject mainJSONObject = weatherJSONObject.getJSONObject("main");
			int temperature = mainJSONObject.getInt("temp");
			int pressure = mainJSONObject.getInt("pressure");
			int humidity = mainJSONObject.getInt("humidity");

			weather.setCountry(country);
			weather.setTemperature(temperature);
			weather.setHumidity(humidity);
			weather.setPressure(pressure);
		} catch (JSONException e) {
			System.out.println("test");
			e.printStackTrace();
		}

		return weather;
	}
}

7、主布局文件，将WeatherBean中的内容在手机中展现。

package com.example.jsonparser;

import java.net.URL;

import com.example.jsonparser.model.WeatherBean;

import android.os.Bundle;
import android.app.Activity;
import android.view.View;
import android.widget.EditText;

public class MainActivity extends Activity {

	private String url1 = "http://api.openweathermap.org/data/2.5/weather?q=";
	private EditText location, country, temperature, humidity, pressure;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		location = (EditText) findViewById(R.id.editText1);
		country = (EditText) findViewById(R.id.editText2);
		temperature = (EditText) findViewById(R.id.editText3);
		humidity = (EditText) findViewById(R.id.editText4);
		pressure = (EditText) findViewById(R.id.editText5);
	}

	public void open(View view) {

		try {
			URL url = new URL(url1 + location.getText().toString());
			System.out.println(url);
			WeatherBean weatherBean = JSONUtil.getWeatherBean(url);
			country.setText(weatherBean.getCountry());
			humidity.setText(weatherBean.getHumidity() + "");
			pressure.setText(weatherBean.getPressure() + "");
			temperature.setText(weatherBean.getTemperature() + "");
			System.out.println("test2");

		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}