Intellij JSP - Servlet Config/ Servlet Context Init Parameter(파라미터 초기화 및 공유)

Servlet Config/ Servlet Context Init Parameter(서블릿 파라미터 초기화 및 공유)

• Project - InitParam

  • ServletInitParam.java

      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;
      import java.io.IOException;
      import java.io.PrintWriter;
    
      public class ServletInitParam extends HttpServlet {
              protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {}
    
              protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
                      response.setContentType("text/html; charset=utf-8");
    
                      String id = getInitParameter("id");
                      String pw = getInitParameter("pw");
                      String desc = getInitParameter("desc");
    
                      PrintWriter out = response.getWriter();
                      out.println("<title>form result</title>" +
                                      "당신이 입력한 정보입니다.<br>" +
                                      "<b>ID</b> : " + id + "<br>" +
                                      "<b>Password</b> : " + pw + "<br>" +
                                      "<b>자기소개</b><br>" +
                                      desc);
              }
      }
    

  • web.xml

      <?xml version="1.0" encoding="UTF-8"?>
      <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
                       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
                       xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
                       version="4.0">
    
          ...
    
          <servlet>
                  <servlet-name>InitParam</servlet-name>
                  <servlet-class>example.ServletInitParam</servlet-class>
          </servlet>
          <servlet-mapping>
                  <servlet-name>InitParam</servlet-name>
                  <url-pattern>/initParam</url-pattern>
          </servlet-mapping>
    
          ...
    
      </web-app>
    

• 특정 Servlet의 Parameter 초기화

  • web.xml 사용

    • web.xml에 매핑한 Servlet 태그 안에서 파라미터 초기화

        <servlet>
                <servlet-name>InitParam</servlet-name>
                <servlet-class>example.ServletInitParam</servlet-class>
      
                <!--추가-->
                <init-param>
                        <param-name>id</param-name>
                        <param-value>qwer</param-value>
                </init-param>
                <init-param>
                        <param-name>pw</param-name>
                        <param-value>1234</param-value>
                </init-param>
                <init-param>
                        <param-name>desc</param-name>
                        <param-value>Hello</param-value>
                </init-param>
      
        </servlet>
        <servlet-mapping>
                <servlet-name>InitParam</servlet-name>
                <url-pattern>/initParam</url-pattern>
        </servlet-mapping>
      

    • 매핑된 URL로 접근하면 초기화 시켜놓은 파라미터가 출력된 것을 볼 수 있다

      

  • Annotation 사용

    • ServletInitParam.java의 클래스 위에 아래의 어노태이션을 추가

        @WebServlet(name = "ServletInitParam", urlPatterns = {"/initParam"},
                initParams = {@WebInitParam(name = "id", value = "qwer"), @WebInitParam(name = "pw", value = "1234"),
                                @WebInitParam(name = "desc", value = "Hello")})
      

    • 마찬가지로 초기화 시켜놓은 파라미터가 출력된 것을 볼 수 있다

      

• Servlet Context을 사용해 모든 Servlet에 파라미터 공유

  • web.xml에 Context Param을 초기화

    • web.xml에 아래의 코드 추가

        <context-param>
                <param-name>id</param-name>
                <param-value>qwer</param-value>
        </context-param>
        <context-param>
                <param-name>pw</param-name>
                <param-value>asdf</param-value>
        </context-param>
      

    • ServletContextParam.java

        import javax.servlet.ServletException;
        import javax.servlet.annotation.WebServlet;
        import javax.servlet.http.HttpServlet;
        import javax.servlet.http.HttpServletRequest;
        import javax.servlet.http.HttpServletResponse;
        import java.io.IOException;
        import java.io.PrintWriter;
      
        @WebServlet(urlPatterns = {"/contextParam"})
        public class ServletContextParam extends HttpServlet {
                protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { }
      
                protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
                        response.setContentType("text/html;charset=utf-8");
                        String id = getServletContext().getInitParameter("id");
                        String pw = getServletContext().getInitParameter("pw");
      
                        PrintWriter out = response.getWriter();
                        out.println("<title>form result</title>" +
                                        "당신이 입력한 정보입니다.<br>" +
                                        "<b>ID</b> : " + id + "<br>" +
                                        "<b>Password</b> : " + pw );
                }
        }
      

  • 결과 화면. ServletContextParam 뿐 아니라 다른 Servlet에서도 파라미터가 공유된다

    

• 신입SW인력을 위한 실전 JSP Servlet