public static String request(String httpUrl, String httpArg) {

        BufferedReader reader = null;

        String result = null;

        StringBuffer sbf = new StringBuffer();

        httpUrl = httpUrl + "?" + httpArg;

        try {

            URL url = new URL(httpUrl);

            HttpURLConnection connection = (HttpURLConnection) url

                    .openConnection();

            connection.setRequestMethod("GET");

            /**setRequestProperty（key,value）

             * Sets the general request property. If a property with the key already

             * exists, overwrite its value with the new value.

             *  设置通用的请求属性。如果该key对应的的属性值已经存在，那么新值将覆盖以前的值

             * <p> NOTE: HTTP requires all request properties which can

             * legally have multiple instances with the same key

             * to use a comma-seperated list syntax which enables multiple

             * properties to be appended into a single property.

             *提示：HTTP要求拥有相同key值的多个实例的所有请求属性，可以使用逗号分隔的列表语法，这样就可以将多个属性附加到单个属性中

             * @param   key     the keyword by which the request is known

             *                  (e.g., "<code>Accept</code>").

             * @param   value   the value associated with it.

             * @throws IllegalStateException if already connected

             * @throws NullPointerException if key is <CODE>null</CODE>

             * @see #getRequestProperty(java.lang.String)

             */

            connection.setRequestProperty("apikey",  "71e4b699*********cf44ebb02cd2");

            connection.connect();

            InputStream is = connection.getInputStream();

            reader = new BufferedReader(new InputStreamReader(is, "UTF-8"));

            String strRead = null;

            while ((strRead = reader.readLine()) != null) {

                sbf.append(strRead);

                sbf.append("\r\n");

            }

            reader.close();

            result = sbf.toString();

        } catch (Exception e) {

            e.printStackTrace();

        }

        return result;

    }

String httpUrl = "http://apis.baidu.com/heweather/weather/free";

String httpArg = "city=wuhan";

String jsonResult = request(httpUrl, httpArg);

JSONObject obj = JSONObject.fromObject(jsonResult);

String result = obj.getString("HeWeather data service 3.0");

JSONArray arr = JSONArray.fromObject(result);

obj = arr.getJSONObject(0);

result = obj.getString("now");