java automate website login

code

1. class define

   1. ctor

       private HttpURLConnection conn;
      
       public Auth() {
           // make sure cookies is turn on
           CookieHandler.setDefault(new CookieManager());
       }
      

   2. send post

       /**
        * send post request
        * @param url url
        * @param params params
        * @return response
        * @throws Exception
        */
       public String sendPost(String url, String params) throws Exception {
      
           URL obj = new URL(url);
           conn = (HttpURLConnection) obj.openConnection();
      
           // Acts like a browser
           conn.setUseCaches(false);
           conn.setRequestMethod("POST");
           // conn.setRequestProperty("Host", "your.api.host");
           // conn.setRequestProperty("User-Agent", USER_AGENT);
           // conn.setRequestProperty("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8");
           // conn.setRequestProperty("Accept-Language", "en-US,en;q=0.5");
      
           // conn.setRequestProperty("Connection", "keep-alive");
           // conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
           // conn.setRequestProperty("Content-Length", Integer.toString(params.length()));
      
           conn.setDoOutput(true);
           conn.setDoInput(true);
      
           // Send post request
           DataOutputStream wr = new DataOutputStream(conn.getOutputStream());
           wr.writeBytes(params);
           wr.flush();
           wr.close();
      
           // int responseCode = conn.getResponseCode();
           // System.out.println("\nSending 'POST' request to URL : " + url);
           // System.out.println("Post parameters : " + params);
           // System.out.println("Response Code : " + responseCode);
      
           return getResponse();
       }
      

   3. send get

       /**
        * sent get request
        * @param url url
        * @param params params
        * @return response
        * @throws Exception
        */
       public String sendGet(String url, String params) throws Exception {
      
           URL obj = new URL(url);
           conn = (HttpURLConnection) obj.openConnection();
      
           // default is GET
           conn.setRequestMethod("GET");
      
           conn.setUseCaches(false);
      
           // act like a browser
           String USER_AGENT = "Mozilla/5.0";
           conn.setRequestProperty("User-Agent", USER_AGENT);
           conn.setRequestProperty("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8");
           conn.setRequestProperty("Accept-Language", "en-US,en;q=0.5");
      
           conn.setDoOutput(true);
           conn.setDoInput(true);
      
           // Send post request
           DataOutputStream wr = new DataOutputStream(conn.getOutputStream());
           wr.writeBytes(params);
           wr.flush();
           wr.close();
      
          return getResponse();
      
       }
      

   4. get response

       /**
        * get response
        * @return response
        * @throws IOException
        */
       private String getResponse() throws IOException {
           BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
           String line = br.readLine();
           StringBuilder sb = new StringBuilder();
           while (line != null) {
               sb.append(line);
               line = br.readLine();
           }
           return sb.toString();
       }
      

2. usage

    // 0. auth
    Auth auth = new Auth();
   
    // 1. login first
    String loginUrl = "http://...";
    String loginParams = "username=...&password=...";
    auth.sendPost(loginUrl, loginParams);
   
    // 2. post example
    String apiUrl = "http://...";
    String apiParams = "...";
    System.out.println(auth.sendPost(apiUrl, apiParams));
   
    // 3. get example
    apiUrl = "http://...";
    apiParams = "...";
    System.out.println(auth.sendGet(apiUrl, apiParams));
   

reference

1. how-to-automate-login-a-website-java-example