[SalesForce] oAuth – how to acquire an access token from another org via an Apex callout

I want to actually connect to a salesforce environment in the background and retrieve information there. I don't want to be redirected anywhere with a token in the url. I want to be able to get the token in my webservice like this :

public with sharing class AP_SandboxRefreshInitSetup {
   public String domain;
   public string endpoint;
   String username;
   String password;
   String clientId = 'my client id';
   String clientSecret = 'my secret'; 

   public AP_SandboxRefreshInitSetup(String domain,string username, string pwd){
      this.domain = (domain != null ? domain : 'https:test.salesforce.com'); 
      this.username = username;
      this.password = pwd;       
   }    
   public void getToken1(){
      String Access_Token;
      Http httpCls = new Http();
      HttpRequest request = new HttpRequest();
      request.setEndpoint(domain + '/services/oauth2/authorize');
      request.setMethod('POST');

      request.setHeader('Content-Type','application/x-www-form-urlencoded');        
      request.setBody('response_type=code' + 
                    '&client_id=' + clientId + 
                    '&redirect_uri=https://127.0.0.1/' + 
                    '&username=' + username +
                    '&password=' + password);        

      //sending the json to the request body
      httpResponse response = httpCls.send(request); 
      system.debug('## response:' + response);

       if(response.getStatusCode() == 200){            
         system.debug('## response message :' + response.getBody()); 
         JSONParser parser = JSON.createParser(response.getBody());

         while (parser.nextToken() != null) {
            if ((parser.getCurrentToken() == JSONToken.FIELD_NAME) && 
             (parser.getText() == 'access_token')) 
            {
                parser.nextToken();
                Access_Token = parser.getText();    
            }
            system.debug('## Access_Token :' + Access_Token);
          } 
       }
       else{
          system.debug('## response status :' + response.getStatus()); 
          system.debug('## response message :' + response.getBody()); 
       }
    }
}

I Keep getting status found, with status code 302.

My redirectUri, clientid and client secret is correct.