java interface call

This kind of problem has been encountered in production, and the interface call problem of java is recorded.

One is the json method;

 public static String sendPost(String url, JSONObject obj)throws IOException{
                   OutputStreamWriter out = null;
                   BufferedReader reader = null;
                   String response="";
                   
/*                   String paramStr = "";
                if (null != param) { // Traverse the parameter Map and add it to the collection
                    Set<String> keySet = param.keySet();
                    for (String key : keySet) {
                        paramStr = paramStr + key + ":" + param.get(key) + "&";
                    }
                }
                int lastAndIndex = paramStr.lastIndexOf("&");
                if (lastAndIndex != -1) {
                    paramStr = paramStr.substring(0, lastAndIndex);
                }
                
                System.out.println("地址===" + url);
                System.out.println("入参===" + paramStr);*/
                
                   try {
                       URL httpUrl = null ; // HTTP URL class uses this class to create connections
                        // create URL 
                       httpUrl = new URL(url);
                        // establish connection 
                       HttpURLConnection conn = (HttpURLConnection) httpUrl.openConnection();
                       conn.setRequestProperty( "accept", "*/*"); // Set common request properties 
                       conn.setRequestProperty("Charset", "UTF-8" );
                       conn.setRequestMethod("POST");
                       conn.setRequestProperty("Content-Type", "application/json");
                       conn.setRequestProperty("connection", "keep-alive");
                       conn.setUseCaches( false ); // Set not to cache 
                       conn.setInstanceFollowRedirects( true );
                       conn.setDoOutput(true);
                       conn.setDoInput(true);
                       conn.connect();
                       //POST请求
                       out = new OutputStreamWriter(
                               conn.getOutputStream());
                       out.write(obj.toJSONString());
                       out.flush();
                       // Read response 
                       reader = new BufferedReader( new InputStreamReader(
                               conn.getInputStream()));
                       String lines;
                       while ((lines = reader.readLine()) != null) {
                           lines = new String(lines.getBytes(), "utf-8");
                           response+=lines;
                       }
                       reader.close();
                       // Disconnect 
                       conn.disconnect();
                   } catch (Exception e) {
                   System.out.println( "Exception sending POST request!"+ e);
                   e.printStackTrace ();
                   }
                   // Use finally block to close output stream, input stream 
                   finally {
                    try {
                        if (out!= null ){
                           out.close();
                       }
                       if(reader!=null){
                           reader.close();
                       }
                   }
                   catch(IOException ex){
                       ex.printStackTrace();
                   }
               }
           
                   return response;
               }

Another common str call interface;

    /**
     * Send a POST request to the specified URL
     * @param url the URL to send the request to
     * @param param Request parameter, the request parameter should be in the form of name1=value1&name2=value2.
     * The response result of the remote resource represented by
      @return */ public static String sendPostWebReq(String url, Map<String, Object> param, int i) throws Exception {
     
        String paramStr = "" ;
         if ( null != param) { // Traverse the parameter Map and add it to the collection 
            Set<String> keySet = param.keySet();
             for (String key : keySet) {
                paramStr = paramStr + key + "=" + param.get(key) + "&";
            }
        }
        int lastAndIndex = paramStr.lastIndexOf("&");
        if (lastAndIndex != -1) {
            paramStr = paramStr.substring(0, lastAndIndex);
        }
        
        System.out.println("地址===" + url);
        System.out.println("入参===" + paramStr);
        
        PrintWriter out = null;
        BufferedReader in = null;
        String result = "";
        try {
            URL realUrl = new URL (url);
            HttpURLConnection conn = (HttpURLConnection) realUrl.openConnection(); // Open the connection with the URL 
            conn.setRequestProperty("accept", "*/*"); // Set the general request property 
            conn.setRequestProperty("Content- Type", "application/json" );
            conn.setRequestProperty("connection", "Keep-Alive");
            conn.setRequestProperty("Charset", "UTF-8");
            conn.setDoOutput( true ); // The following two lines must be set to send a POST request 
            conn.setDoInput( true ); // Get the output stream corresponding to the URLConnection object 
            out = new PrintWriter( new OutputStreamWriter(conn.getOutputStream(), "UTF- 8")); // Send request parameters 
            out.print(paramStr); // flush the buffer of the output stream 
            out.flush();
            in = new BufferedReader( new InputStreamReader(conn.getInputStream(), "UTF-8")); // Define BufferedReader input stream to read URL response 
            String line;
             while ((line = in.readLine()) != null ) {
                result += line;
            }
        } catch (Exception e) {
            System.out.println( "An exception occurred when sending POST request!" + e);
             throw e;
        } finally { // Use finally block to close output stream, input stream 
            try {
                 if (in != null ) in.close();
            } catch (IOException ex) { }
            if (out != null) out.close();
        }
        return result;
    }