How to expose a salesforce apex class as Rest API

salesforce lightning,

1. Create connected app and generate user secret and key
2. Give Full access for this project under connected app permission
3. Create your apex class and test in  workbench://use this url to call from workbench /services/apexrest/GetCase2/5009000001NxD87
Apex code

@RestResource(urlMapping='/GetCase2/*')
global with sharing class RestCaseCreatorurl {

    @HttpGet
    global static Case getCaseById() {
        RestRequest request = RestContext.request;
        // grab the caseId from the end of the URL
        String caseId = request.requestURI.substring(request.requestURI.lastIndexOf('/')+1);
       Case result =  [SELECT CaseNumber,Subject,Status,Origin,Priority FROM Case WHERE Id = :caseId];
        return result;
     
        }
   
    @HttpPost
    global static  String createcase1(String status, String origin){
       
        Case cs = new Case();
        cs.Status = status;
        cs.Origin = origin;
        insert cs;
        return cs.id;
    }
   
   
}

4. JAva code
       /*Java code to access
       package sfdc_rest;
import java.io.IOException;
import java.io.InputStream;
import java.net.URISyntaxException;

import org.apache.http.client.methods.*;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
import org.apache.http.ParseException;
import org.apache.http.util.EntityUtils;
import org.apache.http.client.utils.URIBuilder;
import org.apache.http.client.ClientProtocolException;
import org.json.JSONObject;
import org.json.JSONTokener;
import org.json.JSONException;
public class Main {
static final String USERNAME = "narenrr@yahoo.com";
static final String PASSWORD = "pwdWHVAUUcVWbxXMmKFQDEl1sgK0";
static final String LOGINURL = "https://login.salesforce.com";
static final String GRANTSERVICE =
"/services/oauth2/token?grant_type=password";
static final String CLIENTID = "3MVG9Y6d_Btp4xp7zpH04V6xgnCGIjiRvaGyUe3CIaIwVd5KmnEfStMNlYeql3EN3UugSvGlQ2pUh0QfkK4lj";
static final String CLIENTSECRET = "2948595789758136914";
public static void main(String[] args) {
DefaultHttpClient httpclient = new DefaultHttpClient();
// Assemble the login request URL
String loginURL = LOGINURL +
GRANTSERVICE +
"&client_id=" + CLIENTID +
"&client_secret=" + CLIENTSECRET +
"&username=" + USERNAME +
"&password=" + PASSWORD;
// Login requests must be POSTs
HttpPost httpPost = new HttpPost(loginURL);
HttpResponse response = null;
try {
// Execute the login POST request
response = httpclient.execute(httpPost);
} catch (ClientProtocolException cpException) {
// Handle protocol exception
} catch (IOException ioException) {
// Handle system IO exception
}
// verify response is HTTP OK
final int statusCode =response.getStatusLine().getStatusCode();
if (statusCode != HttpStatus.SC_OK) {
System.out.println("Error authenticating to Force.com:"+statusCode);
// Error is in EntityUtils.toString(response.getEntity())
return;
}
String getResult = null;
try {
getResult = EntityUtils.toString(response.getEntity());
} catch (IOException ioException) {
// Handle system IO exception
}
JSONObject jsonObject = null;
String loginAccessToken = null;
String loginInstanceUrl = null;
try {
jsonObject = (JSONObject) new JSONTokener(getResult).nextValue();
loginAccessToken = jsonObject.getString("access_token");
loginInstanceUrl = jsonObject.getString("instance_url");
} catch (JSONException jsonException) {
// Handle JSON exception
}
System.out.println(response.getStatusLine());
System.out.println("Successful login");
System.out.println(" instance URL: "+loginInstanceUrl);
System.out.println(" access token/session ID:"+loginAccessToken);
// release connection

HttpGet httpget = new HttpGet();//loginInstanceUrl +  "/services/data/v30.0/sobjects/GetCase/5009000001NxD81");
httpget.addHeader("Authorization", "OAuth " + loginAccessToken);
HttpResponse response1 = null;
URIBuilder builder;
try {
    builder = new URIBuilder(loginInstanceUrl + "/services/apexrest/devlight1973/GetCase/5009000001NxD81");

            httpget.setURI(builder.build());
        } catch (URISyntaxException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }

String getResult1 = null;
    try{
    response1 =httpclient.execute(httpget);
    }catch(Exception e){
        System.out.println("error");
    }
System.out.println(response1.getStatusLine().getStatusCode() );
    if (response1.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                        try {
   
                            // Do the needful with entity.
                         
                            try {
                                getResult1 = EntityUtils.toString(response1.getEntity());
                            } catch (ParseException e) {
                                // TODO Auto-generated catch block
                                System.out.println(e.getMessage());
                            } catch (IOException e) {
                                // TODO Auto-generated catch bloc=
                                e.printStackTrace();
                                System.out.println(e.getMessage());
                            }
       
                            jsonObject = (JSONObject) new JSONTokener(getResult1).nextValue();
                           
   
                            System.out.println("Query response: " + jsonObject);
                        }catch(JSONException e){
                                       
                           
                        }

                                httpPost.releaseConnection();
}
}}
       */