2. JSP 활용 - EL Tag

1. EL Tag 기본

<!-- quiz.jsp -->
<form action="quiz1-result.jsp">
	<p><input type="text" name="userid" placeholder="ID"></p>
	<p><input type="password" name="pw1" placeholder="Password"></p>
	<p><input type="password" name="pw2" placeholder="Password 확인"></p>
	<p><input type="text" name="name" placeholder="이름"></p>
	<p><input type="number" name="yyyy" placeholder="출생년도"></p>
	
	<p>
		<select name="mm">
			<%for (int i = 1; i <= 12; i++) { %>
			<option><%=i %></option>
			<% } %>
		</select>
	</p>
	<p><input type="number" name="dd" min="1" max="31" placeholder="출생일"></p>
	<p><input type="submit" name="" placeholder="가입신청"></p>
</form>





<!-- quiz.result -->

<jsp:useBean id="join" class="quiz.Quiz1DTO" />
<jsp:setProperty property="*" name="join"/>

<%
	request.setCharacterEncoding("UTF-8");

	// POST방식의 요청이 아니라면  quiz1.jsp로 보내기
	if (request.getMethod().equals("POST") == false) {
		response.sendRedirect("quiz1.jsp");
	}
%>

	<table>
		<tr>
			<th>id</th>
			<th>이름</th>
			<th>비밀번호</th>
			<th>생년월일</th>
		</tr>
		<tr>
			<td>${join.id }</td>
			<td>${join.name }</td>
			<td>********</td>
			<td>${join.yyyy }-${join.mm }-${join.dd }</td>
		</tr>
	</table>

<※ 결과는 다음과 같습니다.>

public class Circle {
	private double radius;
	private double length;
	private double square;
	
	@Override
	public String toString() {
		String format = "반지름 : %.2f\n, 둘레 : %.2f\n, 넓이 : %.2f\n";
		return String.format(format, radius, length, square);
	}
	
	
	public void calc() {
		if(radius != 0) {
			length = 2 * 3.14 * radius;
			square = radius * radius * 3.14;
		}
	}
	
	
	public double getRadius() {
		return radius;
	}
	public void setRadius(double radius) {
		this.radius = radius;
	}
	public double getLength() {
		return length;
	}
	public void setLength(double length) {
		this.length = length;
	}
	public double getSquare() {
		return square;
	}
	public void setSquare(double square) {
		this.square = square;
	}	
}

<jsp:useBean id="test" class="velog.Circle" />
<jsp:setProperty property="radius" name="test" value="50.7"/>
${test.calc() }
<h3>\${test } : ${test }</h3>
<h3>\${pageSope.test } : ${pageSope.test }</h3>
<h3>\${requestScope.test } : ${requestScope.test }</h3>
<h3>\${sessionScope.test } : ${sessionScope.test }</h3>
<h3>\${applicationScope.test } : ${applicationScope.test }</h3>

<%
	String[] arr = {"짱구", "맹구", "훈이", "유리", "철수"};
	pageContext.setAttribute("arr", arr);
	
	List<String> list = Arrays.asList(arr);
	pageContext.setAttribute("list", list);
	
	HashMap<String, Integer> map = new HashMap<>();
	map.put("나단비", 5);
	map.put("john", 20);	
	pageContext.setAttribute("map", map);
%>

<h3>배열/리스트/맵 접근</h3>
<!-- 배열에서는 자료형을 컬렉션에서는 제네릭 타입을 맞춰주면서 출력 -->
<h3><%=((String[])pageContext.getAttribute("arr"))[1] %></h3>
<h3>\${arr[1] } : ${arr[1] }</h3>
<br>
<h3><%=((List<String>)pageContext.getAttribute("list")).get(2) %></h3>
<h3>\${list[2] } : ${list[2] }</h3>
<br>

<h3><%=((HashMap<String, Integer>)pageContext.getAttribute("map")).get("이지은") %> 살</h3>
<h3>\${map['이지은'] } : ${map['이지은'] }살</h3>
<h3>\${map.john } : ${map.john }살</h3>

<※ 결과는 다음과 같습니다.>

2. EL Tag 연산자