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
1，工具类

/**
 * 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, > oauth2GetOpenid(String appid,String code,String appsecret) {
        String requestUrl = GetPageAccessTokenUrl.replace(\"APPID\", appid).replace(\"SECRET\", appsecret).replace(\"CODE\", code);  
        HttpClient client = null;  
        Map<String, > result =new HashMap<String, >();  
        try {     
            client = new DefaultHttpClient();  
            HttpGet httpget = new HttpGet(requestUrl);  
            ResponseHandler<String> responseHandler = new BasicResponseHandler();  
            String response = client.execute(httpget, responseHandler);  
            JSON  OpenidJSONO=JSON .from (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;  
    }  
}

2，接口

/**
     * 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
      GetOpenid(String 你的小程序APPID, String code, String 你的小程序对应秘钥) {
        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~

1，工具类

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_ \";

        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;
    }
}

2，接口

@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);
        JSON  json  = JSON .from (result);

        String openid = json .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

1，工具类

/**
 * 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);
            JSON  OpenidJSONO = JSON .from (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);
            JSON  OpenidJSONO = JSON .from (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;
    }
}

2，接口

/**
     * 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！
[这是我博客园地址](https://www.cnblogs.com/lxwt/p/10154540.html)