java通过ip地址获取地理位置信息

第一步，要先获取到客户端的ip地址(百度一大堆，在这就不多说了了，想了解的可以自行百度)：
这里需要注意的是本地开启apache服务的时候，当你调用这个方法的时候(包括访问jsp或者是html进行异步请求)，获取到的ip还是内网的ip,并不是真实ip。不过没关系，当项目上生产、放服务器上的时候是可以获取到真实的ip的。

 public static  String getIp(HttpServletRequest request){
             String ipAddress = request.getHeader("x-forwarded-for"); 
                if(ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress)) {  
                    ipAddress = request.getHeader("Proxy-Client-IP"); 
                }  
                if(ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress)) {  
                    ipAddress = request.getHeader("WL-Proxy-Client-IP"); 
                }  
                if(ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress)) {  
                    ipAddress = request.getRemoteAddr(); 
                    if(ipAddress.equals("127.0.0.1") || ipAddress.equals("0:0:0:0:0:0:0:1")){  
                        //根据网卡取本机配置的IP  
                        InetAddress inet=null; 
                        try {  
                            inet = InetAddress.getLocalHost(); 
                        } catch (UnknownHostException e) {  
                            e.printStackTrace(); 
                        }  
                        ipAddress= inet.getHostAddress(); 
                    }  
                }  
                //对于通过多个代理的情况，第一个IP为客户端真实IP,多个IP按照','分割  
                if(ipAddress!=null && ipAddress.length()>15){ //"***.***.***.***".length() = 15  
                    if(ipAddress.indexOf(",")>0){  
                        ipAddress = ipAddress.substring(0,ipAddress.indexOf(",")); 
                    }  
                }  
                return ipAddress; 
        }

第二步，ip到手了，找个第三方的接口吧，百度，高德的都可以，高德返回的json比较好解析。
在这之前要创建链接

/** * 读取 * @param rd * @return * @throws IOException */
     private static String readAll(Reader rd) throws IOException {
            StringBuilder sb = new StringBuilder();
            int cp;
            while ((cp = rd.read()) != -1) {
                sb.append((char) cp);
            }
            return sb.toString();
        }

        /** * 创建链接 * @param url * @return * @throws IOException * @throws JSONException */
        private static JSONObject readJsonFromUrl(String url) throws IOException, JSONException {
            InputStream is = new URL(url).openStream();
            try {
                BufferedReader rd = new BufferedReader(new InputStreamReader(is, Charset.forName("UTF-8")));
                String jsonText = readAll(rd);
                JSONObject json = new JSONObject(jsonText);
                return json;
            } finally {
                is.close();
            }
        }

 /** * 百度获取城市信息 * @param ip * @return * @throws JSONException * @throws IOException */
 public static String baiduGetCityCode() throws JSONException, IOException{

             String ip="";
             //百度ak，自己去申请就可以
             String ak="";
             //这里调用百度的ip定位api服务 详见 http://api.map.baidu.com/lbsapi/cloud/ip-location-api.htm
             JSONObject json = readJsonFromUrl("http://api.map.baidu.com/location/ip?ip="+ip+"&ak="+ak+"&coor=bd09ll");
             Object obj = ((JSONObject) json.get("content")).get("address_detail");
             String s=obj.toString();           
             JSONObject j = new JSONObject(s);
             int city_code=(int) j.get("city_code");
             String code=String.valueOf(city_code);
             return code;
        }

  /** * 高德获取城市信息 * @return * @throws JSONException * @throws IOException */
        public static String guideGetCityCode() throws JSONException, IOException{

             String ip="";
             //高德key
             String key="";
             JSONObject json = readJsonFromUrl("http://restapi.amap.com/v3/ip?ip="+ip+"&key="+key+"");
             //String province = (String) json.get("province");
            // String city = (String) json.get("city");
             String adcode = (String) json.get("adcode");
             return adcode;
          }