JSP | Servlet 사용 예제 | 환율계산기 | 구구단 | P 로그인 (관리자 계정) | 서블릿 초기화 파라미터 | 데이터 공유

환율 계산기 만들기 html 파일 없이 Servlet만 이용

package kr.gov.httpservlet2;

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 CalcServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
	private static float USD_RATE = 1100.91F; //달러
	private static float JPY_RATE = 10.62F;	  //엔화
	private static float CNY_RATE = 168.59F;  //위안
	private static float GBP_RATE = 1493.58F; //파운드
	private static float EUR_RATE = 1343.59F; //유로

    public CalcServlet() {
     
    }

	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();
		writer.println("<html><title>환율 계산기</title>");
		writer.println("<font size=5>환율 계산기</font><br/> ");
		writer.println("<form name='frmCalc' method='get' action='Calc' >");
		writer.println("원화 : <input type='text' name='won' size=10 />");
		writer.println("<select name='operator' >");
		writer.println("<option value='doller' >달러</option>");
		writer.println("<option value='en' >엔화</option>");
		writer.println("<option value='wian' >위안</option>");
		writer.println("<option value='pound' >파운드</option>");
		writer.println("<option value='euro' >유로</option>");
		writer.println("</select>");
		
		writer.println("<input type='hidden' name='command' value='calculate'>");
		writer.println("<input type='submit' value='변환' />");
		writer.println("</form></html>");
		
		String command = request.getParameter("command");
		String won = request.getParameter("won");
		String operator = request.getParameter("operator");
		
		//환율 계산결과 출력
		if(command != null && command.equals("calculate")){
			String result = calculate(Float.parseFloat(won), operator);
			
			writer.println("<html><font size=10>변환 결과</font></br>");
			writer.println("<font size=10>" +result+ "</font></br>");
			writer.println("<a href='Calc'>환율 계산기</a>");
			
			return;
		}
		
		writer.close();
	}
	
	//환율 계산하는 메서드
	private static String calculate(float won, String operator) {
		String result = null;
		
		if(operator.equals("doller")) {
			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;
	}
	
	
	
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	
	}

}

Float.parseFloat => 값을 실수 값으로 파싱

디버깅 코드 더블클릭 후 F11키 디버깅

구구단 출력

<!DOCTYPE html>
<html>
<head>
	<meta charset="UTF-8">
	<title>구구단</title>
</head>
<body>
	<h1>출력할 구구단의 수 입력해 주세요.</h1>
	<form action="gugu" method="get">
		출력할 구구단 : <input type="text" name="number" /><br/>
		<input type="submit" value="구구단 출력">
	</form>
</body>
</html>

package kr.gov.httpservlet3;

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;

/**
 * Servlet implementation class GuguServlet
 */
@WebServlet("/gugu")
public class GuguServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public GuguServlet() {
    	
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
		System.out.println("doGet() 호출");
		
		request.setCharacterEncoding("UTF-8");
		response.setContentType("text/html; charset=UTF-8");
		PrintWriter writer = response.getWriter();
		
		int number = Integer.parseInt(request.getParameter("number"));
		
		//예외를 처리하는 코드 추가
		if(number < 1 || number > 9) {
			writer.print("<html><head></head><body>");
			writer.print("<h1>구구단은 2~9단 사이입니다.</h1>");
			writer.print("</body></html>");
			return;
		}
		
		writer.print("<table border=1 width=800 align=center>");
		writer.print("<tr align=center bgcolor='#ffff66'>");
		writer.print("<td colspan=4>"+number+ "단 출력 </td>" );
		
		for (int i = 1; i < 10; i++) {
			//홀수하고 짝수에 따라서 배경색을 바꿔준다.
			if(i % 2 == 0) {
				writer.print("<tr align=center bgcolor='#ACFAS8'>");
			}else {
				writer.print("<tr align=center bgcolor='#81BEF7'>");
			}
			writer.print("<td width=200>" +number+ "</td>");
			writer.print("<td width=200>" +i+ "</td>");
			writer.print("<td width=200>" +number+ "*" +i+ "</td>");
			writer.print("<td width=200>" +number * i+  "</td>");
			writer.print("</tr>");
		}
		writer.print("</table>");
		writer.close();
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

	}

}

예외처리 화면

자바스크립트로 서블릿에 요청하기

로그인 예외처리 자바스크립트

<!DOCTYPE html>
<html>
<head>
	<meta charset="UTF-8">
	<title>로그인 화면</title>
</head>
<body>
	<form name="frmLogin" action="login" method="post" enctype="UTF-8">
		아이디 : <input type="text" name="user_id" /><br/>
		비밀번호 : <input type="password" name="user_pw" /><br/>
		<input type="button" onclick="func_validate()" value="로그인" />
		<input type="reset" value="재입력" />
		<!-- hidden 속성 : 클라이언트에게 숨겨진 내용으로 서버에 전송하고자 할 때 사용함.(로그인 시간, IP 등등) -->
		<input type="hidden" name="user_address" value="구미시 원평동" /> 
	</form>
	<script type="text/javascript">
		function func_validate() {
			 /* frmLogin 변수 : documnet(웹페이지 화면)객체에 아래에 있는
			 frmLogin 테그 이름을 대입함.*/
			var frmLogin = document.frmLogin;
			var user_id = frmLogin.user_id.value;
			var user_pw = frmLogin.user_pw.value;
			
			if( (user_id.length == 0) || (user_id == "") || 
					(user_pw.length == 0) || (user_pw == "") ){
				alert("아이디와 비밀번호는 필수 사항입니다.");
			}
			else {
				frmLogin.method = "post";
				frmLogin.action = "login";
				frmLogin.submit();
			}
				
		};
	</script>
</body>
</html>

package kr.gov.httpservlet;

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;

/**
 * Servlet implementation class LoginServlet
 */
@WebServlet("/login")
public class LoginServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public LoginServlet() {

    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		System.out.println("doPost()호출");
		
		request.setCharacterEncoding("UTF-8");
		response.setContentType("text/html; charset=UTF-8");
		
		PrintWriter out = response.getWriter();
		
		String id = request.getParameter("user_id");
		String pw = request.getParameter("user_pw");
		String address = request.getParameter("user_address");
		
		System.out.println("아이디 : " + id);
		System.out.println("비밀번호 : " + pw);
		System.out.println("주소 : " + address);
		
		String data = "<html><body>";
		data += "아이디 : " +id+ "<br/>";
		data += "비밀번호 : " +pw+ "<br/>";
		data += "주소 : " +address+ "<br/>";
		data += "</html></body>";
		
		out.print(data);
	}

}

서블릿 초기화 파라미터 ServletConfig

web.xml

톰켓 서버자체에 특정 파라미터 설정한 것을 사용함. => 우선순위가 높음 둘 다 있을 경우.

특정 서블릿에서만 매개변수를 사용하는 용도로 web.xml에 추가

<?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" id="WebApp_ID" version="3.1">
  <display-name>Chap04_Servlet-3</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>
  
  <!-- 첫번째 방법 -->
  <servlet>
  	<!-- 특정 서블릿을 지정하는 코드 -->
  	<servlet-name>initParam</servlet-name>
  	<servlet-class>kr.gov.httpservlet2.InitParam</servlet-class>
  	
  	<!-- 특정서블릿(kr.gov.httpservlet2.InitParam)에만 적용된는 부분이다. 
  		 초기화 파라미터를 init-param테그를 이용하여 지정한다. -->
  	<init-param>
  		<param-name>id</param-name>
  		<param-value>admin</param-value>
  	</init-param>
  	
  	<init-param>
  		<param-name>pw</param-name>
  		<param-value>0217</param-value>
  	</init-param>
	
	<init-param>
  		<param-name>path</param-name>
  		<param-value>C:\\workspace-jsp</param-value>
  	</init-param>
  	
  </servlet>
  <!-- 서블릿 매핑코드 -->
  <servlet-mapping>
  	<servlet-name>initParam</servlet-name>
  	<url-pattern>/InitP</url-pattern>
  </servlet-mapping>
  
</web-app>

package kr.gov.httpservlet2;

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;

/**
 * Servlet implementation class InitParam
 */
//@WebServlet("/InitParam")
public class InitParam extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public InitParam() {
      
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		System.out.println("doGet 호출");
		
		String id = this.getInitParameter("id");
		String pw = this.getInitParameter("pw");
		String path = this.getInitParameter("path");
		
		response.setContentType("text/html; charset=UTF-8");
		PrintWriter out = response.getWriter();
		out.println("<html><head></head><body>");
		out.println("아이디 : " +id+ "<br/>");
		out.println("비밀번호 : " +pw+ "<br/>");
		out.println("경로 : " +path+ "<br/>");
		out.println("</body></html>");
		
		out.close();
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	
	}

}

서블릿 초기화 파라미터 ServletConfig 다른 방법

어노테이션 이용 (관리자 계정에 사용)

package kr.gov.httpservlet2;

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

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

/**
 * 아래와 같이 어노테이션을 적용하기 위해서는 web.xml에 기술되어 있는 부분
 * 일단 주석처리함.
 * 주석처리를 해야 아래코드가 적용됨.
 * 어노테이션을 이용해서 직접 초기화 파라미터 값을 지정
 */
/*
 * 소결론 : 초기화 파라미터를 사용하는 곳은, 보통 관리자 계정을 많이 사용하고,
 * 보통은 web.xml파일에 기술하는것이 바람직함.
 */
//두번째 방법
@WebServlet(urlPatterns = {"/InitP"},
			initParams = {
					@WebInitParam(name = "id", value = "scott"),
					@WebInitParam(name = "pw", value = "tiger"),
					@WebInitParam(name = "path", value = "C:\\workspace-jsp")
			}
		
		)
public class InitParam extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public InitParam() {
      
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		System.out.println("doGet 호출");
		
		String id = this.getInitParameter("id");
		String pw = this.getInitParameter("pw");
		String path = this.getInitParameter("path");
		
		response.setContentType("text/html; charset=UTF-8");
		PrintWriter out = response.getWriter();
		out.println("<html><head></head><body>");
		out.println("아이디 : " +id+ "<br/>");
		out.println("비밀번호 : " +pw+ "<br/>");
		out.println("경로 : " +path+ "<br/>");
		out.println("</body></html>");
		
		out.close();
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	
	}

}

데이터 공유 Servlet Context

하나의 프로젝트 안에 여러 서블릿 파일에서 함께 공유하면서 사용할 수 있도록
context-param태그를 이용해서 파라미터 값을 설정한다.
특정 서블릿 매핑하는 코드가 없는 것을 알 수 있다.

<?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" id="WebApp_ID" version="3.1">
  <display-name>Chap04_Servlet-3</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>
  
  <!-- 첫번째 방법 -->
<!--   <servlet>
  	특정 서블릿을 지정하는 코드
  	<servlet-name>initParam</servlet-name>
  	<servlet-class>kr.gov.httpservlet2.InitParam</servlet-class>
  	
  	특정서블릿(kr.gov.httpservlet2.InitParam)에만 적용된는 부분이다. 
  		 초기화 파라미터를 init-param테그를 이용하여 지정한다.
  	<init-param>
  		<param-name>id</param-name>
  		<param-value>admin</param-value>
  	</init-param>
  	
  	<init-param>
  		<param-name>pw</param-name>
  		<param-value>0217</param-value>
  	</init-param>
	
	<init-param>
  		<param-name>path</param-name>
  		<param-value>C:\\workspace-jsp</param-value>
  	</init-param>
  	
  </servlet>
  서블릿 매핑코드
  <servlet-mapping>
  	<servlet-name>initParam</servlet-name>
  	<url-pattern>/InitP</url-pattern>
  </servlet-mapping> -->
  
  <!-- 하나의 프로젝트 안에 여러 서블릿파일에서 함깨 공유하면서 사용할수 있도록
  	   context-param테그를 이용해서 파라미터 값을 설정함.
  	   특정 서블릿 매핑하는 코드가 없는 것을 알수 있다, -->
  <context-param>
  	<param-name>id</param-name>
  	<param-value>scott55</param-value>
  </context-param>
    <context-param>
  	<param-name>pw</param-name>
  	<param-value>tiger55</param-value>
  </context-param>
    <context-param>
  	<param-name>path</param-name>
  	<param-value>C:\\workspace-jsp</param-value>
  </context-param>
  
</web-app>

this.getServletContext(). getInitParameter() 사용

package kr.gov.httpservlet3;

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;

/**
 * Servlet implementation class ContextInitParam
 */
@WebServlet("/ContextIP")
public class ContextInitParam extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public ContextInitParam() {
 
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		System.out.println("doGet() 호출");
		
		String id = this.getServletContext().getInitParameter("id");
		String pw = this.getServletContext().getInitParameter("pw");
		String path = this.getServletContext().getInitParameter("path");
		
		response.setContentType("text/html; charset=UTF-8");
		PrintWriter out = response.getWriter();
		out.println("<html><head></head><body>");
		out.println("아이디 : " +id+ "<br/>");
		out.println("비밀번호 : " +pw+ "<br/>");
		out.println("경로 : " +path+ "<br/>");
		out.println("</body></html>");
		
		out.close();
		
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	
	}

}

같은 패키지에 공유가 되는지 확인

package kr.gov.httpservlet3;

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;

/**
 * Servlet implementation class AnotherContextInitParamUse
 */
@WebServlet("/Another")
public class AnotherContextInitParamUse extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public AnotherContextInitParamUse() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		String id = this.getServletContext().getInitParameter("id");
		String pw = this.getServletContext().getInitParameter("pw");
		String path = this.getServletContext().getInitParameter("path");
		
		response.setContentType("text/html; charset=UTF-8");
		PrintWriter out = response.getWriter();
		out.println("<html><head></head><body>");
		out.println("아이디 : " +id+ "<br/>");
		out.println("비밀번호 : " +pw+ "<br/>");
		out.println("경로 : " +path+ "<br/>");
		out.println("</body></html>");
		
		out.close();
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}

}

공유가 되는 것을 확인할 수 있다.

웹 어플리케이션 감시 ServletContextListener

JSP | Servlet 사용 예제 | 환율계산기 | 구구단 | P 로그인 (관리자 계정) | 서블릿 초기화 파라미터 | 데이터 공유 | 웹 어플리케이션 감시

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