[Servlet] getParameter / 아주아주 간단한 회원가입, 환율계산, 구구단출력, 로그인 페이지
28 Oct 2021 -
4 minute read
사용자가 입력한 데이터 가져오기 - getParameter()
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<form><input type="submit"...></form>를 사용해 데이터를 서버로 전송하면 해당 Servlet 파일에서 HttpServletRequest 객체를 이용해 Parameter 값을 얻을 수 있다. -
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getParameter(name) : 해당 name의 value를 리턴, 항상 String 형태로 반환
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getParameterValues(name) : 해당 name의 value를 리턴, 값이 여러개인 것 ex) 체크박스
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getParameterNames() : form태그에서 넘어온 name값들을 전부 배열로 리턴
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회원가입 페이지 만들기
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Join.html
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>회원가입</title> </head> <body> <form action="join" method="post"> 이름 : <input type="text" name="name" size=10> <br><br> 아이디 : <input type="text" name="id" size=10> <br><br> 비밀번호 : <input type="password" name="pw" size=10> <br><br> 관심 언어 : <input type="checkbox" name="interest" value="java">JAVA <input type="checkbox" name="interest" value="python">Python <input type="checkbox" name="interest" value="js">JavaScript <input type="checkbox" name="interest" value="c">C <br><br> 이메일 수신 여부 : <input type="radio" name="email" value="y" checked="checked">예 <input type="radio" name="email" value="y">아니오 <br><br> <select name="route"> <option value="opt1">주위의 소개</option> <option value="opt2" selected="selected">인터넷 검색</option> <option value="opt3">기타</option> </select> <br><br> <input type="submit" value="가입하기"> <input type="reset" value="다시 입력하기"> </form> </body> </html> -
Join.java
import java.io.IOException; import java.io.PrintWriter; import java.util.Arrays; 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("/join") public class Join extends HttpServlet { private static final long serialVersionUID = 1L; public Join() { } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("UTF-8"); String name = request.getParameter("name"); String id = request.getParameter("id"); String pw = request.getParameter("pw"); String[] interest = request.getParameterValues("interest"); String email = request.getParameter("email"); String route = request.getParameter("route"); response.setContentType("text/html; charset=UTF-8"); PrintWriter printWriter = response.getWriter(); printWriter.println("<html><head></head><body>"); printWriter.println("이름 : " + name + "<br>"); printWriter.println("아이디 : " + id + "<br>"); printWriter.println("비밀번호 : " + pw + "<br>"); printWriter.println("관심언어 : " + Arrays.toString(interest) + "<br>"); printWriter.println("이메일 수신 여부 : " + email + "<br>"); printWriter.println("가입 경로 : " + route + "<br>"); printWriter.println("</body></html>"); printWriter.close(); } } -
실행결과
환율 계산기 만들기
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ServletCalc.java
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 ServletCalc extends HttpServlet { private static final long serialVersionUID = 1L; private static double EUR_RATE = 1356.40; private static double USD_RATE = 1167.00; private static double JPY_RATE = 1023.55; private static double CNY_RATE = 183.02; public ServletCalc() { super(); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("UTF-8"); response.setContentType("text/html; charset=UTF-8"); PrintWriter writer = response.getWriter(); String won = request.getParameter("won"); String operator = request.getParameter("operator"); String command = request.getParameter("command"); if (command != null && command.equals("calculate")) { String res = calculate(Double.parseDouble(won), operator); writer.println("<html><h3>" + res + "</h3>"); writer.println("<br><a href='calc'>다시 조회하기</a></html>"); return; } writer.println("<html><head><title>환율 계산</title></head>"); writer.println("<body><form name='calc' method='get' action='calc'>"); writer.println("원화 : <input type='text' name='won' size=10>"); writer.println("<select name='operator'>"); writer.println("<option value='eur'>유로</option>"); writer.println("<option value='usd'>달러</option>"); writer.println("<option value='jpy'>엔</option>"); writer.println("<option value='cny'>위안</option>"); writer.println("</select>"); writer.println("<input type='hidden' name='command' value='calculate'>"); writer.println("<input type='submit' value='환율조회'>"); writer.println("</form></body></html>"); } private static String calculate(double won, String operator) { String res = null; if (operator.equals("eur")) { res = String.format("%.2f", won / EUR_RATE); } else if (operator.equals("usd")) { res = String.format("%.2f", won / USD_RATE); } else if (operator.equals("jpy")) { res = String.format("%.2f", won / JPY_RATE); } else if (operator.equals("cny")) { res = String.format("%.2f", won / CNY_RATE); } return res; } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { } } -
실행결과
구구단 출력 페이지 만들기
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Gugudan.html
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>구구단</title> </head> <body> <h3>구구단 출력하기</h3> <form action="gugudan" method="get"> <input type="text" name="num" size=2>단 출력 <br> <br> <input type="submit" value="출력하기"> </form> </body> </html> -
ServletGugudan.java
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("/gugudan") public class ServletGugudan extends HttpServlet { private static final long serialVersionUID = 1L; public ServletGugudan() { super(); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("UTF-8"); response.setContentType("text/html; charset=UTF-8"); PrintWriter writer = response.getWriter(); // getParameter() : 리턴 타입 String int num = Integer.parseInt(request.getParameter("num")); if (num<2 || num>9) { return; } writer.println("<table width=100>"); writer.println("<tr align=center><td colspan=2>" + num + "단</td>"); for (int i = 2; i < 10; i++) { if (i % 2 == 0) { writer.println("<tr bgcolor='#F6EABE'>"); } else { writer.println("<tr bgcolor='#FEF5ED'>"); } writer.println("<td width=50>" + num + "*" + i + "</td>"); writer.println("<td width=50>" + num*i + "</td>"); writer.println("</tr>"); } writer.println("</table>"); writer.close(); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { } } -
실행결과
자바스크립트를 사용해 로그인 페이지 만들기
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login.html
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>로그인</title> </head> <body> <form name="loginForm" action="login" method="post" enctype="UTF-8"> 아이디 : <input type="text" name="uid"> <br><br> 비밀번호 : <input type="password" name="upw"> <br><br> <input type="button" onclick="fnValidate()" value="로그인"> <input type="reset" value="다시입력하기"> </form> <script src="loginVal.js"></script> </body> </html> -
loginVal.js
function fnValidate(){ let loginForm = document.loginForm; let uid = loginForm.uid.value; let upw = loginForm.upw.value; if((uid.length == 0) || uid == ""){ alert("아이디를 입력해주세요."); } else if((upw.length == 0) || upw == ""){ alert("비밀번호를 입력해주세요."); } else { loginForm.submit(); } }; -
ServletLogin.java
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("/login") public class ServletLogin extends HttpServlet { private static final long serialVersionUID = 1L; public ServletLogin() { super(); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("UTF-8"); response.setContentType("text/html; charset=UTF-8"); PrintWriter out = response.getWriter(); out.print("<h1>로그인 성공! 🎉</h1>"); out.close(); } } -
실행결과
