JSP/init-param

JSP, Servlet init-param example

Soul-Learner 2009. 1. 20. 14:42
모든 JSP에서 사용할 수 있도록 init-param을 설정하는 예

   <servlet>
     <servlet-name>jsp</servlet-name>
     <servlet-class>org.apache.jasper.servlet.JspServlet</servlet-class>
     <init-param>
       <param-name>SAVE_ROOT</param-name>
       <param-value>e:/StMgt</param-value>
     </init-param>
     <load-on-startup>3</load-on-startup>
   </servlet>
   <servlet-mapping>
     <servlet-name>jsp</servlet-name>
     <url-pattern>*.jsp</url-pattern>
   </servlet-mapping>


서블릿과 JSP에 초기화 파라미터를 설정하는 다른 예들

 
<web-app>
  <!-- Init parameters for the servlet ReadInitParams -->

  <servlet>
    <servlet-name>ReadInitParams</servlet-name>
    <servlet-class>oracle.otnsamples.servlets.ReadInitParametersServlet</servlet-class>
    <display-name>Read Initialization Parameters of the Servlet</display-name>
    <init-param>
      <param-name>emailHost</param-name>
      <param-value>151.68.167.201</param-value>
    </init-param> 
    <init-param>
      <param-name>webMaster</param-name>
      <param-value>Savitha Rajeev</param-value>
    </init-param>
   </servlet>


  <!-- Init parameters for the JSP readInitParamJSP -->

   <servlet>

    <servlet-name>readInitParamJSP</servlet-name>

    <jsp-file>/web/readInitParamJSP.jsp</jsp-file>

    <init-param>

      <param-name>sys</param-name>

      <param-value>151.68.167.201</param-value>

    </init-param>

    <init-param>

      <param-name>master</param-name>

      <param-value>OTN Group IDC</param-value>

    </init-param>

  </servlet>

  <servlet-mapping>

     <servlet-name>readInitParamJSP</servlet-name>

     <url-pattern>/web/readInitParamJSP.jsp</url-pattern>

   </servlet-mapping>
</web-app>

위에서 선언한 JSP url-pattern 도 반드시 필요함.


  1. Reading the Init Parameters from the web.xml file

    The ServletConfig object provides a handle to the initialization parameters defined in web.xml. ServletConfig's method: getInitParameter() is used to retrieve the init parameters. The following code snippet illustrates how to read the init parameters from the init() and the service() methods of a servlet.

  1. public void init(ServletConfig config) throws ServletException {
   String emailHost  = config.getInitParameter("emailHost");
   String webMaster  = config.getInitParameter("webMaster");
}
    

    or 

public void service(HttpServletRequest request, HttpServletResponse response)
    
 throws ServletException, IOException  {
    

  String host   = getServletConfig().getInitParameter("emailHost");
    
      String master = getServletConfig().getInitParameter("webMaster");}

To retrieve all the init parameters, use Enumeration and ServletConfig's getInitParmeterNames(). For example,

public void init(ServletConfig config) throws ServletException {
   Enumeration params = config.getInitParameterNames();

   // Print the init parameter names and values to the console
   while (params.hasMoreElements()) {
       String name = (String) params.nextElement();
       System.out.println("Parameter Name: " + name +
                          " Value: " + config.getInitParameter(name));
   }
}


Reading the init parameters from the web.xml file in a JSP

The implicit object - ServletConfig can be read either in the jspInit() method or directly to retrieve the values of init parameters. Following is the code snippet to retrieve the values from readInitParamJSP.jsp

readInitParamJSP.jsp 
<%@ page language="java"%>

<html>

<head><title>Read Init params from a JSP</title></head>

<body>

<%!

  String emailHost  = null;

  String webMaster = null;    

   
  public void jspInit() {

    ServletConfig config = getServletConfig();

    emailHost  = config.getInitParameter("emailHost");

    webMaster  = config.getInitParameter("webMaster"); 

  }

%>

<table border="1">

 <tr><td>email server</td><td><%=emailHost%></td></tr>

 <tr><td>WebMaster</td><td><%=webMaster%></td></tr>

</table>
<% // It can also be read directly from the implicit object - config %>

<%=config.getInitParameter("sys")%><br><br>

<%=config.getInitParameter("master")%></body>

</html>