JSP 페이지 스크립트 요소

jsp(Model1) 2020. 5. 10. 18:18

●스크립트 릿 <% %>

-스크립트 릿은 가장 일반적으로 JSP페이지에서 많이 쓰이는 스크립트요소로 주로 프로그래밍의 로직을 기술할 때 많이 쓰인다.

-스크립트 릿에서 선언한 변수는 JSP 페이지가 서블릿으로 변환될 때 지역변수로 사용된다.

▶문법

자바 코드 삽입

●선언문(declaration) <%! %>

-선언문은 일반적으로 JSP페이지에서 자바의 멤버변수(전역변수) 또는 멤버 메소드로 사용하고자 할 때 주로 사용되는 프로그래밍의 로직 기술이다.

-선언문의 변수는 서블릿으로 변환될 때 멤버변수로 변환되고 선언문에서의 메소드는 서블릿에서 메소드로 만들어 진다.

▶문법

<%!

자바 코드 삽입

●표현식(Expression) <%= %>

-표현식은 일반적으로 JSP페이지에서 자바의 System.out.println()과 유사하게 사용된다. 데이터 출력을 할 때 주로 사용되는 프로그래밍의 로직 기술이다.

-System.out.println()은 콘솔에 표시할 때 쓰지만 표현식은 브라우저에 표현할 때 쓴다(화면 출력).

▶문법

<%=

자바 코드 삽입

*jsp코드를 만들면 서블릿 코드도 자동으로 만들어 진다. (JVM에 의해.워크스페이스의 .metadata에서 검색해보면 나온다.확장자가 Count10_jsp.java로 나온다.)

Count10.jsp의 서블릿으로 바뀐 코드(Count10_jsp.java)

/*
 * Generated by the Jasper component of Apache Tomcat
 * Version: Apache Tomcat/9.0.34
 * Generated at: 2020-05-10 08:39:17 UTC
 * Note: The last modified time of this file was set to
 *       the last modified time of the source file after
 *       generation to assist with modification tracking.
 */
package org.apache.jsp;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.jsp.*;

public final class Count10_jsp extends org.apache.jasper.runtime.HttpJspBase
    implements org.apache.jasper.runtime.JspSourceDependent,
                 org.apache.jasper.runtime.JspSourceImports {

  private static final javax.servlet.jsp.JspFactory _jspxFactory =
          javax.servlet.jsp.JspFactory.getDefaultFactory();

  private static java.util.Map<java.lang.String,java.lang.Long> _jspx_dependants;

  private static final java.util.Set<java.lang.String> _jspx_imports_packages;

  private static final java.util.Set<java.lang.String> _jspx_imports_classes;

  static {
    _jspx_imports_packages = new java.util.HashSet<>();
    _jspx_imports_packages.add("javax.servlet");
    _jspx_imports_packages.add("javax.servlet.http");
    _jspx_imports_packages.add("javax.servlet.jsp");
    _jspx_imports_classes = null;
  }

  private volatile javax.el.ExpressionFactory _el_expressionfactory;
  private volatile org.apache.tomcat.InstanceManager _jsp_instancemanager;

  public java.util.Map<java.lang.String,java.lang.Long> getDependants() {
    return _jspx_dependants;
  }

  public java.util.Set<java.lang.String> getPackageImports() {
    return _jspx_imports_packages;
  }

  public java.util.Set<java.lang.String> getClassImports() {
    return _jspx_imports_classes;
  }

  public javax.el.ExpressionFactory _jsp_getExpressionFactory() {
    if (_el_expressionfactory == null) {
      synchronized (this) {
        if (_el_expressionfactory == null) {
          _el_expressionfactory = _jspxFactory.getJspApplicationContext(getServletConfig().getServletContext()).getExpressionFactory();
        }
      }
    }
    return _el_expressionfactory;
  }

  public org.apache.tomcat.InstanceManager _jsp_getInstanceManager() {
    if (_jsp_instancemanager == null) {
      synchronized (this) {
        if (_jsp_instancemanager == null) {
          _jsp_instancemanager = org.apache.jasper.runtime.InstanceManagerFactory.getInstanceManager(getServletConfig());
        }
      }
    }
    return _jsp_instancemanager;
  }

  public void _jspInit() {	//제일먼저 jsp를 실행하게 되면 init메서드가 실행이 된다. 여기서는 아무 내용이 없기 때문에 아무것도 안함.
  }

  public void _jspDestroy() {
  }
  //init이 실행되고 난 후 Service가 실행이 된다. 그리고 난 후 jspService를 더이상 사용하지 않는다고 하면 Destroy메서드가 실행되고 끝난다.
  public void _jspService(final javax.servlet.http.HttpServletRequest request, final javax.servlet.http.HttpServletResponse response)
      throws java.io.IOException, javax.servlet.ServletException {

    if (!javax.servlet.DispatcherType.ERROR.equals(request.getDispatcherType())) {
      final java.lang.String _jspx_method = request.getMethod();
      if ("OPTIONS".equals(_jspx_method)) {
        response.setHeader("Allow","GET, HEAD, POST, OPTIONS");
        return;
      }
      if (!"GET".equals(_jspx_method) && !"POST".equals(_jspx_method) && !"HEAD".equals(_jspx_method)) {
        response.setHeader("Allow","GET, HEAD, POST, OPTIONS");
        response.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED, "JSP�뱾�� �삤吏� GET, POST �삉�뒗 HEAD 硫붿냼�뱶留뚯쓣 �뿀�슜�빀�땲�떎. Jasper�뒗 OPTIONS 硫붿냼�뱶 �삉�븳 �뿀�슜�빀�땲�떎.");
        return;
      }
    }

    final javax.servlet.jsp.PageContext pageContext;
    javax.servlet.http.HttpSession session = null;
    final javax.servlet.ServletContext application;
    final javax.servlet.ServletConfig config;
    javax.servlet.jsp.JspWriter out = null;
    final java.lang.Object page = this;
    javax.servlet.jsp.JspWriter _jspx_out = null;
    javax.servlet.jsp.PageContext _jspx_page_context = null;


    try {
      response.setContentType("text/html; charset=EUC-KR");
      pageContext = _jspxFactory.getPageContext(this, request, response,
      			null, true, 8192, true);
      _jspx_page_context = pageContext;
      application = pageContext.getServletContext();
      config = pageContext.getServletConfig();
      session = pageContext.getSession();
      out = pageContext.getOut();
      _jspx_out = out;

      out.write("\r\n");
      out.write("<!DOCTYPE html>\r\n");
      out.write("<html>\r\n");
      out.write("<head>\r\n");
      out.write("<meta charset=\"EUC-KR\">\r\n");
      out.write("<title>Insert title here</title>\r\n");
      out.write("</head>\r\n");
      out.write("<body>\r\n");
      out.write("\r\n");
      out.write("<h2>1~10源뚯��쓽 �닽�옄瑜� �솕硫댁뿉 �몴�떆</h2>\r\n");
      out.write("\r\n");

	//1~10源뚯��쓽 �닽�옄瑜� �솕硫댁뿉 異쒕젰�븯�떆�삤.
	for(int i = 1; i<=10; i++){
		System.out.println(i); //�씠嫄� 肄섏넄�뿉 �몴�떆�븯�뒗 寃�

      out.write('\r');
      out.write('\n');
      out.write('	');
      out.print( i );
      out.write("<br>\r\n");
 
	}

      out.write("\r\n");
      out.write("\r\n");
      out.write("\r\n");
      out.write("\r\n");
      out.write("<h2>援ш뎄�떒</h2>\r\n");

	for(int i = 2; i<= 9; i++){
		for(int j = 1; j<=9; j++){
			System.out.print(i+ "*"+ j + "= "+i*j + " ");

      out.write("\r\n");
      out.write("\r\n");
      out.print(
	i + "*" + j + "= " + i*j 
);
      out.write(" &nbsp;\r\n");

		}
		System.out.println();

      out.write("\r\n");
      out.write("<br>\r\n");

	}


      out.write("\r\n");
      out.write("\r\n");
      out.write("</body>\r\n");
      out.write("</html>");
    } catch (java.lang.Throwable t) {
      if (!(t instanceof javax.servlet.jsp.SkipPageException)){
        out = _jspx_out;
        if (out != null && out.getBufferSize() != 0)
          try {
            if (response.isCommitted()) {
              out.flush();
            } else {
              out.clearBuffer();
            }
          } catch (java.io.IOException e) {}
        if (_jspx_page_context != null) _jspx_page_context.handlePageException(t);
        else throw new ServletException(t);
      }
    } finally {
      _jspxFactory.releasePageContext(_jspx_page_context);
    }
  }
}

▶선언문을 사용해야 할 때

>선언문을 사용하지 않고 스크립트 릿 안에 메서드를 만들면

-선언문을 사용하지 않고 스크립트 릿안에 메서드를 만든 jsp

<%@ page language="java" contentType="text/html; charset=EUC-KR"
    pageEncoding="EUC-KR"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="EUC-KR">
<title>Insert title here</title>
</head>
<body>

<%-- 

<%
	public void inCrement(){
}
%> 

스크립트 릿 안에 소스코드를 적어주면 서블릿으로 변환 될 때  _jspService메서드 안에 만들어 지게 되는데
_jspService메서드안에 메서드를 또 만드는 것이기 때문에 오류가 발생하게 된다.
그래서 선언문으로 만들어 줘야한다.(선언문으로 메서드를 만들면 멤버메서드로 만들어 지게 된다.)

--%>

</body>
</html>

-선언문을 사용하지 않고 스크립트 릿안에 메서드를 만든 jsp가 변환된 서블릿

/*
 * Generated by the Jasper component of Apache Tomcat
 * Version: Apache Tomcat/9.0.34
 * Generated at: 2020-05-10 08:57:51 UTC
 * Note: The last modified time of this file was set to
 *       the last modified time of the source file after
 *       generation to assist with modification tracking.
 */
package org.apache.jsp;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.jsp.*;

public final class JSPBank_jsp extends org.apache.jasper.runtime.HttpJspBase
    implements org.apache.jasper.runtime.JspSourceDependent,
                 org.apache.jasper.runtime.JspSourceImports {

  private static final javax.servlet.jsp.JspFactory _jspxFactory =
          javax.servlet.jsp.JspFactory.getDefaultFactory();

  private static java.util.Map<java.lang.String,java.lang.Long> _jspx_dependants;

  private static final java.util.Set<java.lang.String> _jspx_imports_packages;

  private static final java.util.Set<java.lang.String> _jspx_imports_classes;

  static {
    _jspx_imports_packages = new java.util.HashSet<>();
    _jspx_imports_packages.add("javax.servlet");
    _jspx_imports_packages.add("javax.servlet.http");
    _jspx_imports_packages.add("javax.servlet.jsp");
    _jspx_imports_classes = null;
  }

  private volatile javax.el.ExpressionFactory _el_expressionfactory;
  private volatile org.apache.tomcat.InstanceManager _jsp_instancemanager;

  public java.util.Map<java.lang.String,java.lang.Long> getDependants() {
    return _jspx_dependants;
  }

  public java.util.Set<java.lang.String> getPackageImports() {
    return _jspx_imports_packages;
  }

  public java.util.Set<java.lang.String> getClassImports() {
    return _jspx_imports_classes;
  }

  public javax.el.ExpressionFactory _jsp_getExpressionFactory() {
    if (_el_expressionfactory == null) {
      synchronized (this) {
        if (_el_expressionfactory == null) {
          _el_expressionfactory = _jspxFactory.getJspApplicationContext(getServletConfig().getServletContext()).getExpressionFactory();
        }
      }
    }
    return _el_expressionfactory;
  }

  public org.apache.tomcat.InstanceManager _jsp_getInstanceManager() {
    if (_jsp_instancemanager == null) {
      synchronized (this) {
        if (_jsp_instancemanager == null) {
          _jsp_instancemanager = org.apache.jasper.runtime.InstanceManagerFactory.getInstanceManager(getServletConfig());
        }
      }
    }
    return _jsp_instancemanager;
  }

  public void _jspInit() {
  }

  public void _jspDestroy() {
  }

  public void _jspService(final javax.servlet.http.HttpServletRequest request, final javax.servlet.http.HttpServletResponse response)
      throws java.io.IOException, javax.servlet.ServletException {

    if (!javax.servlet.DispatcherType.ERROR.equals(request.getDispatcherType())) {
      final java.lang.String _jspx_method = request.getMethod();
      if ("OPTIONS".equals(_jspx_method)) {
        response.setHeader("Allow","GET, HEAD, POST, OPTIONS");
        return;
      }
      if (!"GET".equals(_jspx_method) && !"POST".equals(_jspx_method) && !"HEAD".equals(_jspx_method)) {
        response.setHeader("Allow","GET, HEAD, POST, OPTIONS");
        response.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED, "JSP�뱾�� �삤吏� GET, POST �삉�뒗 HEAD 硫붿냼�뱶留뚯쓣 �뿀�슜�빀�땲�떎. Jasper�뒗 OPTIONS 硫붿냼�뱶 �삉�븳 �뿀�슜�빀�땲�떎.");
        return;
      }
    }

    final javax.servlet.jsp.PageContext pageContext;
    javax.servlet.http.HttpSession session = null;
    final javax.servlet.ServletContext application;
    final javax.servlet.ServletConfig config;
    javax.servlet.jsp.JspWriter out = null;
    final java.lang.Object page = this;
    javax.servlet.jsp.JspWriter _jspx_out = null;
    javax.servlet.jsp.PageContext _jspx_page_context = null;


    try {
      response.setContentType("text/html; charset=EUC-KR");
      pageContext = _jspxFactory.getPageContext(this, request, response,
      			null, true, 8192, true);
      _jspx_page_context = pageContext;
      application = pageContext.getServletContext();
      config = pageContext.getServletConfig();
      session = pageContext.getSession();
      out = pageContext.getOut();
      _jspx_out = out;

      out.write("\r\n");
      out.write("<!DOCTYPE html>\r\n");
      out.write("<html>\r\n");
      out.write("<head>\r\n");
      out.write("<meta charset=\"EUC-KR\">\r\n");
      out.write("<title>Insert title here</title>\r\n");
      out.write("</head>\r\n");
      out.write("<body>\r\n");
      out.write("\r\n");

	public void inCrement(){	//이부분!!! 메서드 안에 메서드가 또 만들어지게 된다.
	
}

      out.write("\r\n");
      out.write("\r\n");
      out.write("</body>\r\n");
      out.write("</html>");
    } catch (java.lang.Throwable t) {
      if (!(t instanceof javax.servlet.jsp.SkipPageException)){
        out = _jspx_out;
        if (out != null && out.getBufferSize() != 0)
          try {
            if (response.isCommitted()) {
              out.flush();
            } else {
              out.clearBuffer();
            }
          } catch (java.io.IOException e) {}
        if (_jspx_page_context != null) _jspx_page_context.handlePageException(t);
        else throw new ServletException(t);
      }
    } finally {
      _jspxFactory.releasePageContext(_jspx_page_context);
    }
  }
}

-선언문을 사용하여 메서드를 만든 jsp

<%@ page language="java" contentType="text/html; charset=EUC-KR"
    pageEncoding="EUC-KR"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="EUC-KR">
<title>Insert title here</title>
</head>
<body>

<%!
	public void increment(){
	
}
%>

</body>
</html>

-선언문을 사용하여 메서드를 만든 jsp가 변환된 서블릿

/*
 * Generated by the Jasper component of Apache Tomcat
 * Version: Apache Tomcat/9.0.34
 * Generated at: 2020-05-10 09:07:28 UTC
 * Note: The last modified time of this file was set to
 *       the last modified time of the source file after
 *       generation to assist with modification tracking.
 */
package org.apache.jsp;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.jsp.*;

public final class JSPBank_jsp extends org.apache.jasper.runtime.HttpJspBase
    implements org.apache.jasper.runtime.JspSourceDependent,
                 org.apache.jasper.runtime.JspSourceImports {


	public void increment(){	//이부분!!! 메서드 바깥에 멤버메서드(전역메서드)로 
    							//메서드가 만들어 지게 된다.
	
}

  private static final javax.servlet.jsp.JspFactory _jspxFactory =
          javax.servlet.jsp.JspFactory.getDefaultFactory();

  private static java.util.Map<java.lang.String,java.lang.Long> _jspx_dependants;

  private static final java.util.Set<java.lang.String> _jspx_imports_packages;

  private static final java.util.Set<java.lang.String> _jspx_imports_classes;

  static {
    _jspx_imports_packages = new java.util.HashSet<>();
    _jspx_imports_packages.add("javax.servlet");
    _jspx_imports_packages.add("javax.servlet.http");
    _jspx_imports_packages.add("javax.servlet.jsp");
    _jspx_imports_classes = null;
  }

  private volatile javax.el.ExpressionFactory _el_expressionfactory;
  private volatile org.apache.tomcat.InstanceManager _jsp_instancemanager;

  public java.util.Map<java.lang.String,java.lang.Long> getDependants() {
    return _jspx_dependants;
  }

  public java.util.Set<java.lang.String> getPackageImports() {
    return _jspx_imports_packages;
  }

  public java.util.Set<java.lang.String> getClassImports() {
    return _jspx_imports_classes;
  }

  public javax.el.ExpressionFactory _jsp_getExpressionFactory() {
    if (_el_expressionfactory == null) {
      synchronized (this) {
        if (_el_expressionfactory == null) {
          _el_expressionfactory = _jspxFactory.getJspApplicationContext(getServletConfig().getServletContext()).getExpressionFactory();
        }
      }
    }
    return _el_expressionfactory;
  }

  public org.apache.tomcat.InstanceManager _jsp_getInstanceManager() {
    if (_jsp_instancemanager == null) {
      synchronized (this) {
        if (_jsp_instancemanager == null) {
          _jsp_instancemanager = org.apache.jasper.runtime.InstanceManagerFactory.getInstanceManager(getServletConfig());
        }
      }
    }
    return _jsp_instancemanager;
  }

  public void _jspInit() {
  }

  public void _jspDestroy() {
  }

  public void _jspService(final javax.servlet.http.HttpServletRequest request, final javax.servlet.http.HttpServletResponse response)
      throws java.io.IOException, javax.servlet.ServletException {

    if (!javax.servlet.DispatcherType.ERROR.equals(request.getDispatcherType())) {
      final java.lang.String _jspx_method = request.getMethod();
      if ("OPTIONS".equals(_jspx_method)) {
        response.setHeader("Allow","GET, HEAD, POST, OPTIONS");
        return;
      }
      if (!"GET".equals(_jspx_method) && !"POST".equals(_jspx_method) && !"HEAD".equals(_jspx_method)) {
        response.setHeader("Allow","GET, HEAD, POST, OPTIONS");
        response.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED, "JSP�뱾�� �삤吏� GET, POST �삉�뒗 HEAD 硫붿냼�뱶留뚯쓣 �뿀�슜�빀�땲�떎. Jasper�뒗 OPTIONS 硫붿냼�뱶 �삉�븳 �뿀�슜�빀�땲�떎.");
        return;
      }
    }

    final javax.servlet.jsp.PageContext pageContext;
    javax.servlet.http.HttpSession session = null;
    final javax.servlet.ServletContext application;
    final javax.servlet.ServletConfig config;
    javax.servlet.jsp.JspWriter out = null;
    final java.lang.Object page = this;
    javax.servlet.jsp.JspWriter _jspx_out = null;
    javax.servlet.jsp.PageContext _jspx_page_context = null;


    try {
      response.setContentType("text/html; charset=EUC-KR");
      pageContext = _jspxFactory.getPageContext(this, request, response,
      			null, true, 8192, true);
      _jspx_page_context = pageContext;
      application = pageContext.getServletContext();
      config = pageContext.getServletConfig();
      session = pageContext.getSession();
      out = pageContext.getOut();
      _jspx_out = out;

      out.write("\r\n");
      out.write("<!DOCTYPE html>\r\n");
      out.write("<html>\r\n");
      out.write("<head>\r\n");
      out.write("<meta charset=\"EUC-KR\">\r\n");
      out.write("<title>Insert title here</title>\r\n");
      out.write("</head>\r\n");
      out.write("<body>\r\n");
      out.write("\r\n");
      out.write("\r\n");
      out.write("\r\n");
      out.write("</body>\r\n");
      out.write("</html>");
    } catch (java.lang.Throwable t) {
      if (!(t instanceof javax.servlet.jsp.SkipPageException)){
        out = _jspx_out;
        if (out != null && out.getBufferSize() != 0)
          try {
            if (response.isCommitted()) {
              out.flush();
            } else {
              out.clearBuffer();
            }
          } catch (java.io.IOException e) {}
        if (_jspx_page_context != null) _jspx_page_context.handlePageException(t);
        else throw new ServletException(t);
      }
    } finally {
      _jspxFactory.releasePageContext(_jspx_page_context);
    }
  }
}

그냥 스크립트 릿<% %>안에 변수와 메서드를 만들면 지역변수, 지역메서드로 만들어지고

선언문 <%! %>안에 변수와 메서드를 만들면 멤버변수(전역변수), 멤버메서드(전역메서드)로 만들어 지게 된다.

선언문은 개념정도만 알아두면 좋다.

참조 : 인프런 - JSP웹 쇼핑몰 프로그래밍 기본 과정(JSP WEB Programming) - JSP 페이지 디렉티브

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