package demo;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.List;

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

public class checkUser extends HttpServlet {

	public checkUser() {
		super();
	}

	public void destroy() {
		super.destroy(); // Just puts "destroy" string in log
		// Put your code here
	}

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		this.doPost(request, response);
	}

	
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		request.setCharacterEncoding("utf-8");
		response.setCharacterEncoding("utf-8");
	
		List<String> userNames = Arrays.asList("AAA","BBB","CCC");//假設這幾個使用者名稱已被使用 
		
		String username =  request.getParameter("username");  
		PrintWriter out = response.getWriter();
	
		if(userNames.contains(username)){  //返回標誌判斷使用者名稱是否存在
			out.print("yes");  //該使用者名稱已存在
		}
		else{
			out.print("no");  //該使用者名稱不存在
		}
		
	}

	public void init() throws ServletException {
		// Put your code here
	}

}