import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;

public static String sendGet(String url, String charset, int timeout) {
        String result = "";
        try {
            URL u = new URL(url);
            try {
                URLConnection conn = u.openConnection();
                conn.connect();
                conn.setConnectTimeout(timeout);
                BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream(), charset));
                String line = "";
                while ((line = in.readLine()) != null) {

                    result = result + line;
                }
                in.close();
            } catch (IOException e) {
                return result;
            }
        } catch (MalformedURLException e) {
            return result;
        }

        return result;
    }

//address
 public static final String TOKEN_URL = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=APP_ID&secret=SECRET";

import net.sf.json.JSONObject; 
public static String getAccessToken(String appId, String secret) {
        String backData = sendGet(TOKEN_URL.replace("APP_ID", appId).replace("SECRET", secret), "utf-8", 10000);
        log.info("============>Obtain accessToken{}", JSON.toJSONString(backData));
        String accessToken = (String) JSONObject.fromObject(backData).get("access_token");
        return accessToken;
    }

• maven configuration

  
  <!-- https://mvnrepository.com/artifact/net.sf.json-lib/json-lib-ext-spring -->
          <dependency>
              <groupId>net.sf.json-lib</groupId>
              <artifactId>json-lib-ext-spring</artifactId>
              <version>1.0.2</version>
          </dependency>

Get ticket

 public static String getJSApiTicket(String acessToken) {
        //Get token
        String urlStr = "https://api.weixin.qq.com/cgi-bin/ticket/getticket?access_token=" + acessToken + "&type=jsapi";
        String backData = sendGet(urlStr, "utf-8", 10000);
        String ticket = (String) JSONObject.fromObject(backData).get("ticket");
        return ticket;
    }

Get public number openid

//Write your own app ID and SECRET
public static final String PUBLIC_NUMBER_OPEN_ID_URL = "https://api.weixin.qq.com/sns/oauth2/access_token?appid=APP_ID&secret=SECRET&code=CODE&grant_type=authorization_code";

public static Map<String, Object> getPublicNumberOpenId(String code) {
        Map<String, Object> returnMap = new HashMap<>();
        //Get token
        log.info("==========>Obtain unionID,code Yes," + code);
        String backData = sendGet(PUBLIC_NUMBER_OPEN_ID_URL.replace("CODE", code), "utf-8", 10000);
        log.info("==========>Obtain openID: " + backData);
        String openId = (String) JSONObject.fromObject(backData).get("openid");
        returnMap.put("openId", openId);
        return returnMap;
    }

Get small program openid

//Change app ID and SECRET to their own
public static final String SMALL_PROGRAM_OPEN_ID_URL = "https://api.weixin.qq.com/sns/jscode2session?appid=APP_ID&secret=SECRET&js_code=CODE&grant_type=authorization_code";

public static Map<String, Object> getSmallProgramOpenId(String code) {
        Map<String, Object> returnMap = new HashMap<>();
        //Get token
        log.info("==========>Obtain unionID,code Yes," + code);
        String backData = sendGet(SMALL_PROGRAM_OPEN_ID_URL.replace("CODE", code), "utf-8", 10000);
        log.info("==========>Obtain openID: " + backData);
        String openId = (String) JSONObject.fromObject(backData).get("openid");
        returnMap.put("openId", openId);
        return returnMap;
    }

In the next section, I will write about the function of custom message reply