목차
웹 계산기 서블릿 하나로 합치기
- doGet, doPost를 이용
package com.web;
import java.io.IOException;
import java.io.PrintWriter;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/calculator")
public class Calculator extends HttpServlet{
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
Cookie[] cookies = request.getCookies();
String exp = "0";
if(cookies != null) {
for(Cookie c: cookies) {
if(c.getName().equals("exp")) {
exp = c.getValue();
break;
}
}
}
response.setCharacterEncoding("UTF-8");
response.setContentType("text/html; charset=utf-8");
PrintWriter out = response.getWriter();
out.write("<!DOCTYPE html>");
out.write("<html>");
out.write("<head>");
out.write("<meta charset=\"UTF-8\">");
out.write("<title>Insert title here</title>");
out.write("<style>");
out.write("input {");
out.write("width : 50px;");
out.write("height: 50px;");
out.write("}");
out.write(".output {");
out.write("height: 50px;");
out.write("background: #e9e9e9;");
out.write("font-size: 24px;");
out.write("font-weight: bold;");
out.write("text-align:right;");
out.write("padding: 0px 5px;");
out.write("}");
out.write("</style>");
out.write("</head>");
out.write("<body>");
out.write("<form method=\"post\">");
out.write("<table>");
out.write("<tr>");
out.printf("<td class=\"output\" colspan=\"4\">%s</td>", exp);
out.write("</tr>");
out.write("<tr>");
out.write("<td><input type=\"submit\" name=\"operator\" value=\"CE\"></td>");
out.write("<td><input type=\"submit\" name=\"operator\" value=\"C\"></td>");
out.write("<td><input type=\"submit\" name=\"operator\" value=\"BS\"></td>");
out.write("<td><input type=\"submit\" name=\"operator\" value=\"/\"></td>");
out.write("</tr>");
out.write("<tr>");
out.write("<td><input type=\"submit\" name=\"value\" value=\"7\"></td>");
out.write("<td><input type=\"submit\" name=\"value\" value=\"8\"></td>");
out.write("<td><input type=\"submit\" name=\"value\" value=\"9\"></td>");
out.write("<td><input type=\"submit\" name=\"operator\" value=\"*\"></td>");
out.write("</tr>");
out.write("<tr>");
out.write("<td><input type=\"submit\" name=\"value\" value=\"4\"></td>");
out.write("<td><input type=\"submit\" name=\"value\" value=\"5\"></td>");
out.write("<td><input type=\"submit\" name=\"value\" value=\"6\"></td>");
out.write("<td><input type=\"submit\" name=\"operator\" value=\"-\"></td>");
out.write("</tr>");
out.write("<tr>");
out.write("<td><input type=\"submit\" name=\"value\" value=\"1\"></td>");
out.write("<td><input type=\"submit\" name=\"value\" value=\"2\"></td>");
out.write("<td><input type=\"submit\" name=\"value\" value=\"3\"></td>");
out.write("<td><input type=\"submit\" name=\"operator\" value=\"+\"></td>");
out.write("</tr>");
out.write("<tr>");
out.write("<td></td>");
out.write("<td><input type=\"submit\" name=\"value\" value=\"0\"></td>");
out.write("<td><input type=\"submit\" name=\"dot\" value=\".\"></td>");
out.write("<td><input type=\"submit\" name=\"operator\" value=\"=\"></td>");
out.write("</tr>");
out.write("</table>");
out.write("</form>");
out.write("</body>");
out.write("</html>");
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// ServletContext app = getServletContext();
// HttpSession session = request.getSession();
Cookie[] cookies = request.getCookies();
String value = request.getParameter("value");
String operator = request.getParameter("operator");
String dot = request.getParameter("dot");
String exp = "";
if(cookies != null) {
for(Cookie c: cookies) {
if(c.getName().equals("exp")) {
exp = c.getValue();
break;
}
}
}
if(operator != null && operator.equals("=")) {
/* 자바 스크립트 엔진 */
ScriptEngine engine = new ScriptEngineManager().getEngineByName("nashorn");
try {
exp = String.valueOf(engine.eval(exp)); // 지정된 스크립트를 실행
} catch (ScriptException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} else {
exp += (value == null) ? "" : value;
exp += (operator == null) ? "" : operator;
exp += (dot == null) ? "" : dot;
}
Cookie expCookie = new Cookie("exp", exp);
/* 쿠키 삭제 */
if(operator != null && operator.equals("C")) {
expCookie.setMaxAge(0);
}
expCookie.setPath("/calculator");
response.addCookie(expCookie);
response.sendRedirect("calculator");
}
}References
- 뉴렉처:
Servlet / JSP - 🎈vscode 정리
- 🎈2020.12.28
안녕하세요:)