Weather report

        对于大多数的Android手机，天气app都是系统必备的，对于天气预报的功能的实现，最近也做了研究，其实也不是太复杂，主要用到了网络请求以及数据解析方面的内容。下面就来详细介绍下如何在android中实现天气appj基本功能的开发。
1.网络请求，在android系统中，网络请求主要有两种实现方式，URLConnection和httpClient,这两种方式都可以实现网络请求。
（1）URLConnection

        URL url = new URL(path);        URLConnection conn = url.openConnection();        conn.connect();        InputStream in = conn.getInputStream();        BufferedReader buffer = new BufferedReader(new InputStreamReader(in));        String list = buffer.readLine();        while (list != null) {            xml += list;            list = buffer.readLine();        }

        这里的path就是我们要访问的网址，这样我们就可以将网页上的内容按照字符形式读取下来。存到list这个字符串中。（别忘了还要在注册文件中添加访问网络权限）
（2）HttpClient

        HttpClient client = new DefaultHttpClient();        HttpGet get = new HttpGet(path);        HttpResponse response = client.execute(get);        int code = response.getStatusLine().getStatusCode();        if (code == 200) {            InputStream reader = response.getEntity().getContent();            BufferedReader buffer = new BufferedReader(new InputStreamReader(reader));            String list = buffer.readLine();            while (list != null) {                xml += list;                list = buffer.readLine();            }        }

        这里的path同样是网络地址，code是服务器给我们返回的一个值，如果是200，就说明访问成功，404就表示客户端异常，505就表示服务器端异常。不过用这种方式请求的话需要导入两个包httpclient和httpcore,这两个包都在studio文件夹的bin目录下，复制到你项目的libs目录下，还要进行导入，File-project structure-app-dependencies-'+'-File dependency,按照顺序然后选中你要导入的包，确认，就可以了。在导入这两个包后可能还要在build-grade目录下加入以下内容

packagingOptions {        exclude 'META-INF/DEPENDENCIES.txt'        exclude 'META-INF/LICENSE.txt'        exclude 'META-INF/NOTICE.txt'exclude 'META-INF/NOTICE'exclude 'META-INF/LICENSE'exclude 'META-INF/DEPENDENCIES'exclude 'META-INF/notice.txt'exclude 'META-INF/license.txt'exclude 'META-INF/dependencies.txt'exclude 'META-INF/LGPL2.1'}

        这样我们就可以访问网络上的资源了。对于免费的天气api,网上有很多，我用的是这个:http://www.k780.com/api/weather.future,很好用，提供的数据也很全面，实时天气，未来5-7天的，PM2.5和空气指数都有提供，我们只需要对需要的数据进行访问然后获取，接下来就是取出我们所需要的数据了，也就是JSON解析。
2.JSON解析
        JSON类型数据是很常见的数据类型，它比起XML来方便很多，它是以键值对的形式来存储数据的，所以很常用。解析起来非常容易，实例化一个JSONObject类，读取到网页上的内容，也就是上边的list传进去，即JSONObject json = new JSONObject(list),然后直接调用getString()把你需要的信息的键传进去，就能得到对应的值了，很容易。这就是我们实现天气预报的基本过程。下面是博主的一个小小的例子。

public class MainActivity extends Activity {    private TextView temperature;    private TextView weather;    private TextView aqi;    private TextView humidity;    private TextView degree;    private TextView location;    private Button add;    private Message msg;    public  static Handler handler;    public  static String position = "";    public  static  boolean start = false;    LocationClient locationClient = null;    BDLocationListener myListener = new MyLocationListener();    SwipeRefreshLayout swipeRefreshLayout;    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        requestWindowFeature(Window.FEATURE_NO_TITLE);        setContentView(R.layout.activity_main);        add = (Button) findViewById(R.id.buttonId);        temperature = (TextView) findViewById(R.id.tempId);        weather = (TextView) findViewById(R.id.weatherId);        aqi = (TextView) findViewById(R.id.aqiId);        humidity = (TextView) findViewById(R.id.humidityId);        degree = (TextView) findViewById(R.id.degreeId);        location = (TextView) findViewById(R.id.city);        add.setOnClickListener(new ButtonListener());        handler = new Myhandler();        swipeRefreshLayout = (SwipeRefreshLayout) findViewById(R.id.swipeRefresh);        swipeRefreshLayout.setColorSchemeColors(android.R.color.background_light);        swipeRefreshLayout.setSize(10);        swipeRefreshLayout.setProgressBackgroundColor(android.R.color.white);        swipeRefreshLayout.setOnRefreshListener(new reFreshListener());        getLocationThread g = new getLocationThread();                thread t = new thread();                Thread T = new Thread(t, "Refresh");                T.start();       }    public static String getURLConnection(String path) {        String xml = "";        try {            HttpClient client = new DefaultHttpClient();            HttpGet get = new HttpGet(path);            HttpResponse response = client.execute(get);            int code = response.getStatusLine().getStatusCode();            if (code == 200) {                InputStream reader = response.getEntity().getContent();                BufferedReader buffer = new BufferedReader(new InputStreamReader(reader));                String list = buffer.readLine();                while (list != null) {                    xml += list;                    list = buffer.readLine();                }            }        } catch (Exception e) {            e.printStackTrace();        }        return xml;    }    public class reFreshListener implements SwipeRefreshLayout.OnRefreshListener {<span>        @Override        public void onRefresh() {            thread t = new thread();            Thread T = new Thread(t, "Refresh");            T.start();<span style="white-space:pre">        }    }    private class thread implements Runnable {                                                              @Override        public void run() {            String todayXML = "http://api.k780.com:88/?app=weather.today&weaid=";                               String aqiXMl = "http://api.k780.com:88/?app=weather.pm25&weaid=";                                        String futureXML = "http://api.k780.com:88/?app=weather.future&weaid=";                                     String suffixXML = "&&appkey=10003&sign=b59bc3ef6191eb9f747dd4e83c99f2a4&format=json";            String todayWeather = getURLConnection(todayXML + position + suffixXML);            String todayAqi = getURLConnection(aqiXMl + position + suffixXML);            Message msg = new Message();            Bundle bundle = new Bundle();            bundle.putString("todayWeather", todayWeather);            bundle.putString("todayAqi", todayAqi);            msg.setData(bundle);            try {                Thread.sleep(1000);                handler.sendMessage(msg);            } catch (InterruptedException e) {                e.printStackTrace();            }        }    }    public class Myhandler extends Handler {        public void handleMessage(Message msg) {            swipeRefreshLayout.setRefreshing(false);            String todayWeather = msg.getData().getString("todayWeather");            if (todayWeather != null) {                try {                    todayWeather = String.valueOf(new JSONObject(todayWeather).getJSONObject("result"));                    JSONObject json = new JSONObject(todayWeather);                    location.setText(json.getString("citynm"));                    String temp = json.getString("temp_curr");                    final float scale = getApplicationContext().getResources().getDisplayMetrics().density;                    if (temp.length() == 2) {                        temperature.setWidth((int) (84 * scale + 0.5f));                        System.out.println((int) (84 * scale + 0.5f));                    } else if (temp.length() == 3) {                        temperature.setWidth((int) (140 * scale + 0.5f));                    }                    temperature.setText(temp);                    degree.setText("o");                    weather.setText(json.getString("weather"));                    humidity.setText("湿度" + json.getString("humidity") + " " + json.getString("wind") + json.getString("winp"));                } catch (Exception e) {                    e.printStackTrace();                }            }            String todayAqi = msg.getData().getString("todayAqi");            if (todayAqi != null) {                try {                    todayAqi = String.valueOf(new JSONObject(todayAqi).getJSONObject("result"));                    JSONObject json = new JSONObject(todayAqi);                    aqi.setText("空气指数" + json.getString("aqi") + " " + json.getString("aqi_levnm") + "  " + json.getString("aqi_remark"));                } catch (JSONException e) {                    e.printStackTrace();                }            }        }    }

        上面就是实现获取实时天气的主要内容，其实很容易，但是要想实现更全面的功能就比较复杂了，本来我还想做一下定位功能，结果由于阅码能力太渣，读不懂大神们的代码，所以暂时没有实现这个功能，后续会跟进。不过关于定位大家可以用百度地图API，http://developer.baidu.com/map/index.php?title=android-locsdk上面有详细介绍，也可以下载它的Demo来仔细研读。