JAVA获取微信小程序openid和获取公众号openid，以及通过openid获取用户信息

一，首先说明下这个微信的openid

　　为了识别用户，每个用户针对每个公众号会产生一个安全的OpenID，如果需要在多公众号、移动应用之间做用户共通，则需前往微信开放平台，将这些公众号和应用绑定到一个开放平台账号下，绑定后，一个用户虽然对多个公众号和应用有多个不同的OpenID，但他对所有这些同一开放平台账号下的公众号和应用，只有一个UnionID

我用简单自己理解的话来说就是  这个  你在每个公众号 或者小程序  都是在这个小程序或者这个公众号下会有一个openid   你去别的公众号 或者 小程序 这个是会改变的  但是unionid是不管你在哪个小程序或者公众号是唯一不变的。

微信官方提供了 了一个  可以通过用户的openid来获取用户信息，前提是用户必须关注了你的公众号，这个好像要做的话需要关联一个需要三百块钱认证的那个啥来着。这个就先不说了吧，现在我们要说的问题是如何获取openid

二，小程序获取openid

 /**
  * 微信小程序获取openid
  * @author Mr.Lin
  */
 public class GetOpenIDUtil {
     // 网页授权接口
 //    public final static String GetPageAccessTokenUrl = "https://api.weixin.qq.com/sns/oauth2/access_token?appid=APPID&secret=SECRET&code=CODE&grant_type=authorization_code";//
 //    public final static String GetPageAccessTokenUrl = "https://api.weixin.qq.com/sns/jscode2session?appid=APPID&secret=SECRET&js_code=CODE&grant_type=authorization_code";
     public final static String GetPageAccessTokenUrl = "https://api.weixin.qq.com/sns/jscode2session?appid=APPID&secret=SECRET&js_code=CODE&grant_type=authorization_code";
     public  static Map<String,Object> oauth2GetOpenid(String appid,String code,String appsecret) {
         String requestUrl = GetPageAccessTokenUrl.replace("APPID", appid).replace("SECRET", appsecret).replace("CODE", code);
         HttpClient client = null;
         Map<String,Object> result =new HashMap<String,Object>();
         try {
             client = new DefaultHttpClient();
             HttpGet httpget = new HttpGet(requestUrl);
             ResponseHandler<String> responseHandler = new BasicResponseHandler();
             String response = client.execute(httpget, responseHandler);
             JSONObject OpenidJSONO=JSONObject.fromObject(response);
             String openid =String.valueOf(OpenidJSONO.get("openid"));
             String session_key=String.valueOf(OpenidJSONO.get("session_key"));
             String unionid=String.valueOf(OpenidJSONO.get("unionid"));
             String errcode=String.valueOf(OpenidJSONO.get("errcode"));
             String errmsg=String.valueOf(OpenidJSONO.get("errmsg"));

             result.put("openid", openid);
             result.put("sessionKey", session_key);
             result.put("unionid", unionid);
             result.put("errcode", errcode);
             result.put("errmsg", errmsg);
         } catch (Exception e) {
             e.printStackTrace();
         } finally {
             client.getConnectionManager().shutdown();
         }
         return result;
     }
 }

/**
     * 小程序换取openid
     *
     * @param code 识别得到用户id必须的一个值 得到网页授权凭证和用户id
     * @return
     */
    @RequestMapping("/get/openid")
    public @ResponseBody
    Object GetOpenid(String 你的小程序APPID, String code, String 你的小程序秘钥) {
        if (code == null || code.length() == 0) {
            throw new CustomException("code不能为空!");
        }
        return GetOpenIDUtil.oauth2GetOpenid(appid, code, appsecret);

    }
这个code的话我这个一般是前端生成比较好，所以你后台的话，把接口给前端，让他那边传个code，

　三，获取公众号openid~

 public class HttpGetUtil {
     public static String httpRequestToString(String url,
                                              Map<String,String> params) {
         String result = null;
         try {
             InputStream is = httpRequestToStream(url,  params);
             BufferedReader in = new BufferedReader(new InputStreamReader(is,
                     "UTF-8"));
             StringBuffer buffer = new StringBuffer();
             String line = "";
             while ((line = in.readLine()) != null) {
                 buffer.append(line);
             }
             result = buffer.toString();
         } catch (Exception e) {
             return null;
         }
         return result;
     }

     private static InputStream httpRequestToStream(String url,
                                                    Map<String, String> params) {
         InputStream is = null;
         try {
             String parameters = "";
             boolean hasParams = false;
             for(String key : params.keySet()){
                 String value = null;
                 try {
                     value = URLEncoder.encode(params.get(key), "UTF-8");
                 } catch (UnsupportedEncodingException e) {
                     e.printStackTrace();
                 }
                 parameters += key +"="+ value +"&";
                 hasParams = true;
             }
             if(hasParams){
                 parameters = parameters.substring(0, parameters.length()-1);
             }

             url += "?"+ parameters;

             URL u = new URL(url);
             HttpURLConnection conn = (HttpURLConnection) u.openConnection();
             conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
             conn.setRequestProperty("Accept-Charset", "UTF-8");
             conn.setRequestProperty("contentType", "utf-8");
             conn.setConnectTimeout(50000);
             conn.setReadTimeout(50000);
             conn.setDoInput(true);
             //设置请求方式，默认为GET
             conn.setRequestMethod("GET");

             is = conn.getInputStream();
         } catch (UnsupportedEncodingException e) {
             e.printStackTrace();
         } catch (MalformedURLException e) {
             e.printStackTrace();
         } catch (IOException e) {
             e.printStackTrace();
         }
         return is;
     }

     public static String  GetCodeRequest1 = "https://open.weixin.qq.com/connect/oauth2/authorize?appid=APPID&redirect_uri=REDIRECT_URI&response_type=code&scope=SCOPE&state=STATE#wechat_redirect";
     public static String getCodeRequest(String appid){
         HttpClient client = null;
         String result = null;
         String appId = appid;
         String REDIRECT_URI= "";//回调请求地址
         String SCOPE="snsapi_base";

         GetCodeRequest1  = GetCodeRequest1.replace("APPID", urlEnodeUTF8(appId));
         GetCodeRequest1  = GetCodeRequest1.replace("REDIRECT_URI",urlEnodeUTF8(REDIRECT_URI));
         GetCodeRequest1 = GetCodeRequest1.replace("SCOPE", SCOPE);
         result = GetCodeRequest1;

         System.out.println(REDIRECT_URI);

         return result;
     }
     public static String urlEnodeUTF8(String str){
         String result = str;
         try {
             result = URLEncoder.encode(str,"UTF-8");
         } catch (Exception e) {
             e.printStackTrace();
         }
         return result;
     }
 }

@RequestMapping("/get/gzh/openid")
    public @ResponseBody
    String GetGZHOpenid(HttpServletRequest request, HttpServletResponse response) throws IOException {

        String code = request.getParameter("code");//获取code
        Map params = new HashMap();
        params.put("secret", 你的公众号秘钥);
        params.put("appid", 你的公众号APPID);
        params.put("grant_type", "authorization_code");
        params.put("code", code);
        String result = HttpGetUtil.httpRequestToString(
                "https://api.weixin.qq.com/sns/oauth2/access_token", params);
        JSONObject jsonObject = JSONObject.fromObject(result);

        String openid = jsonObject.get("openid").toString();
        LOGGER.debug("code------" + code);
        LOGGER.debug("得到的openid为:" + openid);
        return openid;

    }

四，通过微信获取的openid来获取用户信息

 /**
  * 获取accessToken
  *
  */
 public class GetAccessTokenUtil {
     // 网页授权接口
     public final static String GetPageAccessTokenUrl = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=APPID&secret=APPSECRET";
     public static Map<String, String> getAccessToken(String appid, String appsecret) {
         String requestUrl = GetPageAccessTokenUrl.replace("APPID", appid).replace("APPSECRET", appsecret);
         HttpClient client = null;
         Map<String, String> result = new HashMap<String, String>();
         String accessToken = null;
         try {
             client = new DefaultHttpClient();
             HttpGet httpget = new HttpGet(requestUrl);
             ResponseHandler<String> responseHandler = new BasicResponseHandler();
             String response = client.execute(httpget, responseHandler);
             JSONObject OpenidJSONO = JSONObject.fromObject(response);
             accessToken = String.valueOf(OpenidJSONO.get("access_token"));
             result.put("accessToken", accessToken);
         } catch (Exception e) {
             e.printStackTrace();
         } finally {
             client.getConnectionManager().shutdown();
         }
         return result;
     }
 }

//通过openid获取用户的信息，这个看你需要获取用户的哪些信息,
//  https://mp.weixin.qq.com/wiki?t=resource/res_main&id=mp1421140839   这个是微信官方的获取unionid机制  用户信息
public class GetBasicInformation {
    // 网页授权接口
    public final static String GetPageAccessTokenUrl = "https://api.weixin.qq.com/cgi-bin/user/info?access_token=ACCESS_TOKEN&openid=OPENID&lang=zh_CN";

    public static Map<String, String> getAccessToken(String access_token, String openid) {
        String requestUrl = GetPageAccessTokenUrl.replace("ACCESS_TOKEN", access_token).replace("OPENID", openid);
        HttpClient client = null;
        Map<String, String> result = new HashMap<String, String>();
        try {
            client = new DefaultHttpClient();
            HttpGet httpget = new HttpGet(requestUrl);
            ResponseHandler<String> responseHandler = new BasicResponseHandler();
            String response = client.execute(httpget, responseHandler);
            JSONObject OpenidJSONO = JSONObject.fromObject(response);

//            String accessToken = String.valueOf(OpenidJSONO.get("access_token"));
            String subscribe = String.valueOf(OpenidJSONO.get("subscribe"));
            String nickname = new String(String.valueOf(OpenidJSONO.get("nickname")).getBytes("ISO8859-1"),"UTF-8");
            String sex = String.valueOf(OpenidJSONO.get("sex"));
            String language = String.valueOf(OpenidJSONO.get("language"));
            String city = new String(String.valueOf(OpenidJSONO.get("city")).getBytes("ISO8859-1"),"UTF-8");
            String province = new String(String.valueOf(OpenidJSONO.get("province")).getBytes("ISO8859-1"),"UTF-8");
            String country = new String(String.valueOf(OpenidJSONO.get("country")).getBytes("ISO8859-1"),"UTF-8");
            String headimgurl = String.valueOf(OpenidJSONO.get("headimgurl"));
            String subscribeTime = String.valueOf(OpenidJSONO.get("subscribe_time"));
            String unionid = String.valueOf(OpenidJSONO.get("unionid"));
//            String accessToken =new String(String.valueOf(OpenidJSONO.get("access_token")).getBytes("ISO8859-1"),"UTF-8");
//            String openid =new String(String.valueOf(OpenidJSONO.get("openid")).getBytes("ISO8859-1"),"UTF-8");
//            String openid =new String(String.valueOf(OpenidJSONO.get("openid")).getBytes("ISO8859-1"),"UTF-8");
//            String openid =new String(String.valueOf(OpenidJSONO.get("openid")).getBytes("ISO8859-1"),"UTF-8");
//            String openid =new String(String.valueOf(OpenidJSONO.get("openid")).getBytes("ISO8859-1"),"UTF-8");
//            String openid =new String(String.valueOf(OpenidJSONO.get("openid")).getBytes("ISO8859-1"),"UTF-8");
//            String openid =new String(String.valueOf(OpenidJSONO.get("openid")).getBytes("ISO8859-1"),"UTF-8");
//            String openid =new String(String.valueOf(OpenidJSONO.get("openid")).getBytes("ISO8859-1"),"UTF-8");
//            String openid =new String(String.valueOf(OpenidJSONO.get("openid")).getBytes("ISO8859-1"),"UTF-8");
//            String openid =new String(String.valueOf(OpenidJSONO.get("openid")).getBytes("ISO8859-1"),"UTF-8");
//            String openid =new String(String.valueOf(OpenidJSONO.get("openid")).getBytes("ISO8859-1"),"UTF-8");

//            String openid = String.valueOf(OpenidJSONO.get("openid"));
//            result.put("accessToken", accessToken);
            result.put("subscribe", subscribe);
            result.put("nickname", nickname);
            result.put("sex", sex);
            result.put("language", language);
            result.put("city", city);
            result.put("province", province);
            result.put("country", country);
            result.put("headimgurl", headimgurl);
            result.put("subscribeTime", subscribeTime);
            result.put("unionid", unionid);

//            System.out.println(accessToken+"==================="+unionid);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            client.getConnectionManager().shutdown();
        }
        return result;
    }
}

 /**
      * 微信公众号获取微信unionid和其他个人信息   需要关注公众号
      *
      * @param openid
      * @return
      */
     @RequestMapping("/basic/Information")
     public @ResponseBody
     Map basicInformation(String openid) {
         //得到access_token
         String accessToken = GetAccessTokenUtil.getAccessToken(你的公众号APPID, 你的公众号APPID对应的秘钥).get("accessToken");
         LOGGER.debug("accessToken------" + accessToken);
         return GetBasicInformation.getAccessToken(accessToken, openid);
     }

总结：这个就是微信小程序和微信公众号获取openid  以及通过openid获取unionid以及用户信息的代码，微信开发文档上面看感觉功力不深厚是很难看懂的，这个我也是通过网上或者同事慢慢总结出来的。  请大家多多指教，谢谢！