public class callout {

public static void calloutMethod(){
	Settings__c ts = [SELECT Name, Client_Secret__c, ConsumerKey__c, Password__c, SecurityToken__c,Username__c from Settings__c];



    String clientId = ts.ConsumerKey__c;
    String clientSecret = ts.Client_Secret__c;
    String username=ts.Username__c;
    String password=ts.Password__c+ts.SecurityToken__c; 
    
    String reqbody = 'grant_type=password&client_id='+clientId+'&client_secret='+clientSecret+'&username='+username+'&password='+password;
    
    Http h = new Http ();
    HttpRequest req = new HttpRequest ();
    req.setBody(reqbody);
    req.setMethod('POST');
    req.setEndpoint(ts.URL__c+'/services/oauth2/token');
    
    HttpResponse res = h.send(req);
    OAuth2 objAuthenticationInfo = (OAuth2)JSON.deserialize(res.getbody(), OAuth2.class);
    RequestWrapper reqst=new RequestWrapper();
    if(objAuthenticationInfo.access_token!=null){
    Http h1 = new Http();
    HttpRequest req1 = new HttpRequest();
    
    req1.setHeader('Authorization','Bearer '+objAuthenticationInfo.access_token);
    req1.setHeader('Content-Type','application/json');
    req1.setHeader('accept','application/json');
    req1.setBody(jsonstr);//Send JSON body
    req1.setMethod('POST');
    req1.setEndpoint(ts.URL__c+URL);
    HttpResponse res1 = h1.send(req1);
    system.debug('RESPONSE_BODY'+res1 .getbody());
    }
}
}