[JSP] 환율 계산기 만들기[서블릿(Servlet)을 이용한 환율 계산기 만들기]

1. 환율 계산기 만들기

- CalServlet.java

package ex01;

import java.io.IOException;
import java.io.PrintWriter;

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

@WebServlet("/calc")
public class CalServlet extends HttpServlet{
	private static final float USD_RATE = 0.00081f;
	private static final float JPY_RATE = 0.095f;
	private static final float CNY_RATE = 0.0051f;
	private static final float GBP_RATE = 0.00062f;
	private static final float EUR_RATE = 0.00074f;
	
	@Override
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		request.setCharacterEncoding("utf-8");
		response.setContentType("text/html; charset=utf-8");
		PrintWriter pw = response.getWriter();
		
		String command = request.getParameter("command");
		String won = request.getParameter("won");
		String operator = request.getParameter("operator");
		
		if(command != null && command.equals("calculate")) {
			String result = calculate(Float.parseFloat(won), operator);
			pw.print("<html><font size=10>변환 결과</font><br>");
			pw.print("<font size=10>" + result + "</font><br>");
			pw.print("<a href ='calc'>환율 계산기</a>");
		}
		else {
			pw.print("<html><title>환율 계산기</title>");
			pw.print("<font size=5>환율 계산기</font><br>");
			pw.print("<form name='frmCalc' method='get' action='calc'>");
			pw.print("원화 : <input type='text' name='won' size=10 />");
			pw.print("<select name='operator' >");
			pw.print("<option value='dollar'>달러</option>");
			pw.print("<option value='en'>엔화</option>");
			pw.print("<option value='wian'>위안</option>");
			pw.print("<option value='pound'>파운드</option>");
			pw.print("<option value='euro'>유로</option>");
			pw.print("</select>");
			pw.print("<input type='hidden' name='command' value='calculate' />");
			pw.println("<input type='submit' value='변환' />");
			pw.println("</form>");
			pw.print("</html>");
			pw.close();
		}
	}
	
	private static String calculate(float won, String operator) {
		String result = null;
		
		if(operator.equals("dollar")) {
			result = String.format("%.6f", won * USD_RATE);
		} else if(operator.equals("en")) {
			result = String.format("%.6f", won * JPY_RATE);
		} else if(operator.equals("wian")) {
			result = String.format("%.6f", won * CNY_RATE);
		} else if(operator.equals("pound")) {
			result = String.format("%.6f", won * GBP_RATE);
		} else if(operator.equals("euro")) {
			result = String.format("%.6f", won * EUR_RATE);
		}
		return result;
	}
}