Java սերվիլետ՝ օգտագործելով JSON - տվյալների բազայի միացում և մուտքի վավերացում

package BL;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
 * Servlet implementation class BLServlet
 */
@WebServlet("/BLServlet/*")
public class BLServlet extends HttpServlet {

	enum BLServlet_Request {
		Unknown,
		User
	};

	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public BLServlet() {
        super();
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    	dispatchRequest(request, response);
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	}

	
    private int dispatchRequest(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
        int rc = 0;
        
        HttpSession _HttpSession = request.getSession();
        
        String s_RequestURL = request.getRequestURL().toString();
        String s_RequestURI = request.getRequestURI();
        String s_ContextPath = request.getContextPath();

        String s_Request_Prefix = s_ContextPath;
        String s_Request = s_RequestURI.substring(s_Request_Prefix.length(), s_RequestURI.length());
        if (!s_Request.startsWith("/")) {
            s_Request = "/" + s_Request;
        }
        
        BLServlet_Request _CurrentRequest = requestFromURI(s_Request);
        
        System.out.println("BL servlet Context: " + s_ContextPath + " request URL: " + s_RequestURL + " URI: " + s_RequestURI + " Request: " + s_Request);
        
    	switch (_CurrentRequest) {
			case User:
				rc = new BLRequestUser().handle(request, response);
				break;
			case Unknown:
		        System.out.println("BL servlet Context: received unknown request [" + s_Request + "]");
				break;
    	}
    	
    	return rc;
    }
	

    static BLServlet_Request requestFromURI(final String _uri) {
    	if (_uri.equals("/BLServlet/User")) {
    		return BLServlet_Request.User;
    	}    		
		return BLServlet_Request.Unknown;
    }

    
    static String requestAsString(final BLServlet_Request _request) {
    	switch (_request) {
    		case User:
    			return "User";
    		case Unknown:
    			return "Unknown";
    	}
		return "Unknown";
    }
        	
	
}

package BL;

import java.io.IOException;

import javax.json.Json;
import javax.json.stream.JsonGenerator;
import javax.servlet.http.HttpServletResponse;

public class BLUser {
	
	private String Id = "";
	private String Surname = "";

	public BLUser(String s_Id) {
		Id = s_Id;
		if (s_Id.equals("1")) {
			Surname = "Doe";
		}
	}
	
	public void toJson(HttpServletResponse response) throws IOException {
		JsonGenerator _JsonGenerator = Json.createGenerator(response.getWriter());
		
		_JsonGenerator
			.writeStartObject()
				.write("id", Id)
				.write("surname", Surname)
			.writeEnd();
		_JsonGenerator.close();
	}
}

package BL;

import java.io.IOException;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class BLRequestUser {

	public BLRequestUser() {
	}
	
	public int handle(HttpServletRequest request, HttpServletResponse response) throws IOException {
		String s_UserId = request.getParameter("id");
		if (s_UserId == null) {
			response.setStatus(400);
		}
		else {
			response.setStatus(200);
			response.setContentType("application/json");
			BLUser _BLUser = new BLUser(s_UserId);
			_BLUser.toJson(response);
		}
		
		return 0;
	}
}