[Jsp] 계산기(Calculator) 만들기 예제 (Redirect, Dispatch 방식 포함)
- BACKEND/Servlet&JSP
- 2017. 5. 10. 12:50
o목록
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web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" version="3.1">
<display-name>calculatorWeb</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
</welcome-file-list>
<servlet>
<servlet-name>CalculatorServlet</servlet-name>
<servlet-class>calc.controller.CalculatorServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>CalculatorServlet</servlet-name>
<url-pattern>/calc</url-pattern>
</servlet-mapping>
</web-app>
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CalculatorServlet.java
package calc.controller;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import calc.service.CalculatorService;
public class CalculatorServlet extends HttpServlet {
@Override
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//1. 요청파라미터 조회
request.setCharacterEncoding("UTF-8");//요청파라미터 한글처리.
//피연산자 2
String op1 = request.getParameter("op1");
String op2 = request.getParameter("op2");
//연산자
String operator = request.getParameter("operator");
String result = null;//처리결과를 저장할 변수(성공/실패 메세지)
try{
int operand1 = Integer.parseInt(op1);
int operand2 = Integer.parseInt(op2);
//2. Business Logic 처리(계산) - 연산자 조건에 따라 계산 처리 (조건-if/switch(문자열 비교는 jdk7부터))
CalculatorService service = CalculatorService.getInstance();
result = service.calculate(operand1, operand2, operator);
/*
if(operator.equals("+")){
result = String.format("결과 : %d %s %d = %d", operand1, operator, operand2, operand1+operand2);
}else if(operator.equals("-")){
result = String.format("결과 : %d %s %d = %d", operand1, operator, operand2, operand1-operand2);
}else if(operator.equals("*")){
result = String.format("결과 : %d %s %d = %d", operand1, operator, operand2, operand1*operand2);
}else if(operator.equals("/")){
result = String.format("결과 : %d %s %d = %d", operand1, operator, operand2, operand1/operand2);
}
*/
}catch(NumberFormatException e){
result = "피연산자는 숫자만 입력하십시요.";
}
//3. 처리결과 응답
// calc_result.jsp 호출(이동) - result값을 전달
//Redirect방식으로 수행을 이동. -> jsp로 보내야 하는 값이 있는 경우 => query string으로 전송
// -> 영문/숫자 코드값 전송.
//response.sendRedirect("/calculatorWeb/calc_result.jsp?result="+result);
//요청 디스패치 방식 호출(이동) -> jsp로 보내야 하는 값이 있는 경우. 속성을 이용한다.
request.setAttribute("result", result);
RequestDispatcher rdp = // request.getRequestDispatcher("/calc_result.jsp"); // / -> application의 root 경로
request.getRequestDispatcher("/WEB-INF/view/calc_result.jsp");
rdp.forward(request, response);
/*
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
out.print("<!doctype html>");
out.print("<html><head><title>계산 결과</title></head>");
out.print("<body>");
out.print(result);
out.print("<p><a href='/calculatorWeb/Calculator-form.html'>계산폼</a>");
out.print("</body></html>");
*/
}
}
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Calculator-form.html
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="/calculatorWeb/calc" method="post">
피연산자1 : <input type = "text" name="op1" width="200" size="5"><br>
연산자 : <select name="operator">
<option value="+"> 덧셈 </option>
<option value="-">뺏셈 </option>
<option value="*"> 곱하기 </option>
<option value="/"> 나누기 </option>
</select><br>
피연산자2 : <input type = "text" name="op2" width="200" size="5"><br>
<input type="submit" value="계산" name="b1">
<input type="reset" value="재입력" name="b2">
</form>
</body>
</html>
o결과
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calc_result.jsp
<%@ page contentType="text/html;charset=UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<h2>계산 결과</h2>
<p>
Redirect로 이동 : <%= request.getParameter("result") %><br> <!-- 웹브라우저 상에 출력해라. -->
요청디스패치 이동 : <%=request.getAttribute("result") %> <!-- request.getAttribute("이름") Request객체에 저장된 속성중 이름이 "이름" 인속성 조회 -->
</p>
<a href="/calculatorWeb/Calculator-form.html">계산 폼</a>
</body>
</html>
o결과
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