Making Http call from core java - different ways

There are many ways we make http calls to web server in many situation. We application server always receives requests in many forms and send back response in many forms.

Now a days there are a lots of framework, library available to kame http call easy to the web server like Spring, Struts, Ajax, etc.

 But if the requirement is simple and need just a simple and light weight http call to the server, you will not like to use these heavy library which comes will many extra functionality which you dont need. In this case the best way is to use the inbuild hava http functionality to get response data from the web server.

below are few example which will help you to understand batter

Using HttpConnect

conn = (HttpURLConnection) new URL(url).openConnection();
conn.setRequestMethod(method);
conn.setRequestProperty("X-DocuSign-Authentication", httpAuthHeader);
conn.setRequestProperty("Accept", "application/json");
if (method.equalsIgnoreCase("POST")) {
  conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
  conn.setRequestProperty("Content-Length", Integer.toString(body.length()));
            conn.setDoOutput(true);
}


status = conn.getResponseCode(); // triggers the request
if (status != 200) { //// 200 = OK 
    errorParse(conn, status);
    return;
}

InputStream is = conn.getInputStream();

Another way is using HttpPost

  try {
   // 1. create HttpClient
   HttpClient httpclient = new DefaultHttpClient();

   // 2. make POST request to the given URL
   HttpPost httpPost = new HttpPost(authUrl);

   String json = "";

   // 3. build jsonObject
   JSONObject jsonObject = new JSONObject();
   jsonObject.accumulate("phone", "phone");

   // 4. convert JSONObject to JSON to String
   json = jsonObject.toString();

   // 5. set json to StringEntity
   StringEntity se = new StringEntity(json);

   // 6. set httpPost Entity
   httpPost.setEntity(se);

   // 7. Set some headers to inform server about the type of the
   // content
   httpPost.addHeader("Accept", "application/json");
   httpPost.addHeader("Content-Type", "application/x-www-form-urlencoded");

   // 8. Execute
   HttpResponse httpResponse = httpclient.execute(httpPost);

   // 9. receive response as inputStream
   inputStream = httpResponse.getEntity().getContent();
   String response = getResponseBody(inputStream);
   
   System.out.println(response);

  } catch (ClientProtocolException e) {
   System.out.println("ClientProtocolException : " + e.getLocalizedMessage());
  } catch (IOException e) {
   System.out.println("IOException:" + e.getLocalizedMessage());
  } catch (Exception e) {
   System.out.println("Exception:" + e.getLocalizedMessage());
  }

Updating column 1 or column 2 with value of same column value or different column value of same table

Some time we need to change values of columns of same row of a table.

update  table_name set column1 = column2

you can also put some arithmetic calculation and update table as well. the above query will take the value of column2 and will store it in the column1 of the same row of same table.