-------------------使用百度地图开发平台(lbs),根据经纬度查询商圈出现的问题----------------------

public class BusinessUtil {
    public static String getBusniss(String lonAndLat) throws Exception{
        // 计算sn跟参数对出现顺序有关，get请求请使用LinkedHashMap保存<key,value>，该方法根据key的插入顺序排序；post请使用TreeMap保存<key,value>，该方法会自动将key按照字母a-z顺序排序。所以get请求可自定义参数顺序（sn参数必须在最后）发送请求，但是post请求必须按照字母a-z顺序填充body（sn参数必须在最后）。以get请求为例：http://api.map.baidu.com/geocoder/v2/?address=百度大厦&output=json&ak=yourak，paramsMap中先放入address，再放output，然后放ak，放入顺序必须跟get请求中对应参数的出现顺序保持一致。
        Map paramsMap = new LinkedHashMap<String, String>();
        //paramsMap.put("address", "百度大厦");
        paramsMap.put("callback", "renderReverse");
        paramsMap.put("location", lonAndLat);
        paramsMap.put("output", "json");
        paramsMap.put("pois", "1");
        paramsMap.put("extensions_town", "true");
        paramsMap.put("ak", "写自己的ak");
        // 调用下面的toQueryString方法，对LinkedHashMap内所有value作utf8编码，拼接返回结果address=%E7%99%BE%E5%BA%A6%E5%A4%A7%E5%8E%A6&output=json&ak=yourak
        String paramsStr = toQueryString(paramsMap);
        // 对paramsStr前面拼接上/geocoder/v2/?，后面直接拼接yoursk得到/geocoder/v2/?address=%E7%99%BE%E5%BA%A6%E5%A4%A7%E5%8E%A6&output=json&ak=yourakyoursk
        String wholeStr = new String("/reverse_geocoding/v3/?" + paramsStr + "写自己的sk");
        // 对上面wholeStr再作utf8编码
        String tempStr = URLEncoder.encode(wholeStr, "UTF-8");
        String sn = MD5(tempStr);
        //String url = "http://api.map.baidu.com"+ tempStr + "&sn="+ sn;
        String url = "http://api.map.baidu.com/reverse_geocoding/v3/?"+paramsStr + "&sn=" + sn;
        //调用HttpClient访问Baidu LBS 百度地图开放平台
        HttpClient httpClient = new HttpClient();
        GetMethod get = new GetMethod(url);
        int status = httpClient.executeMethod(get);
        String business = "";
        if(status == 200){
            String response = get.getResponseBodyAsString();
            response = response.replaceAll("renderReverse&&renderReverse\(","");
            response = response.substring(0,response.length()-1);
            JSONObject jo = JSON.parseObject(response);
            JSONObject result = jo.getJSONObject("result");
            //获取商圈
            business = result.getString("business");
            //如果商圈为空,获取具体的地址最小到镇
            if(StringUtils.isEmpty(business)){
                StringBuffer buffer = new StringBuffer();
                JSONObject addr = result.getJSONObject("addressComponent");
                String province = addr.getString("province");
                String city = addr.getString("city");
                String district = addr.getString("district");
                String town = addr.getString("town");
                if(StringUtils.isNotEmpty(province)){
                    buffer.append(province+";");
                }
                if(StringUtils.isNotEmpty(province)){
                    buffer.append(city+";");
                }
                if(StringUtils.isNotEmpty(province)){
                    buffer.append(district+";");
                }
                if(StringUtils.isNotEmpty(province)){
                    buffer.append(town);
                }
                business = buffer.toString();
            }
        }
        return business;
    }

    // 对Map内所有value作utf8编码，拼接返回结果
    public static  String toQueryString(Map<?, ?> data)
            throws UnsupportedEncodingException {
        StringBuffer queryString = new StringBuffer();
        for (Map.Entry<?, ?> pair : data.entrySet()) {
            queryString.append(pair.getKey() + "=");
            queryString.append(URLEncoder.encode((String) pair.getValue(),
                    "UTF-8") + "&");
        }
        if (queryString.length() > 0) {
            queryString.deleteCharAt(queryString.length() - 1);
        }
        return queryString.toString();
    }

    // 来自stackoverflow的MD5计算方法，调用了MessageDigest库函数，并把byte数组结果转换成16进制
    public static String MD5(String md5) {
        try {
            java.security.MessageDigest md = java.security.MessageDigest
                    .getInstance("MD5");
            byte[] array = md.digest(md5.getBytes());
            StringBuffer sb = new StringBuffer();
            for (int i = 0; i < array.length; ++i) {
                sb.append(Integer.toHexString((array[i] & 0xFF) | 0x100)
                        .substring(1, 3));
            }
            return sb.toString();
        } catch (java.security.NoSuchAlgorithmException e) {
        }
        return null;
    }

    public static void main(String[] args) throws  Exception{
        System.out.println(BusinessUtil.getBusniss("40.499603,116.420812"));
        //打印结果
        //北京市;北京市;延庆区;四海镇
    }
}

 上面代码出现问题的解决方法：