獲取web.xml中參數的幾種方法

爲了在web容器啓動時運行指定的類，我們可以在web.xml中配置一個自定義的servlet，複寫init方法即可，如下： web.xml

程序代碼

    <servlet>         <servlet-name>tychoLoader</servlet-name>         <servlet-class>org.junesky.tycho.servlet.TychoLoaderServlet</servlet-class>         <load-on-startup>3</load-on-startup> </servlet>

TychoLoaderServlet.java

程序代碼

public class TychoLoaderServlet extends HttpServlet {     public void init(ServletConfig config) throws ServletException {         //在這裏做相應的處理     }     public void destroy() {     } }

在啓動時，若要爲其配置相應的參數又該如何處理呢？以下介紹幾種常用的方法。 1、在servlet中獲取參數： web.xml

程序代碼

    <servlet>         <servlet-name>tychoLoader</servlet-name>         <servlet-class>org.junesky.tycho.servlet.TychoLoaderServlet</servlet-class>         <init-param>             <param-name>filename</param-name>             <param-value>config/constants.properties</param-value>         </init-param>         <load-on-startup>3</load-on-startup> </servlet>

TychoLoaderServlet.java

程序代碼

public class TychoLoaderServlet extends HttpServlet {     public void init(ServletConfig config) throws ServletException {         super.init(config);         // 利用ServletConfig的getInitParameter來獲取參數         String filename = config.getInitParameter("filename");              ……     }     public void destroy() {     } }

2、在jsp中獲取參數： web.xml

程序代碼

  <context-param>     <param-name>filename</param-name>     <param-value>config/constants.properties</param-value>   </context-param>

jsp

程序代碼

String filename = new String(application.getInitParameter("filename"));

3、在struts中獲取參數： web.xml

程序代碼

    <servlet>         <servlet-name>action</servlet-name>         <servlet-class>org.junesky.tycho.servlet.EncodeActionServlet</servlet-class>         <init-param>             <param-name>config</param-name>             <param-value>/WEB-INF/config/struts-config.xml</param-value>         </init-param>         <init-param>             <param-name>debug</param-name>             <param-value>3</param-value>         </init-param>         <init-param>             <param-name>detail</param-name>             <param-value>3</param-value>         </init-param>         <load-on-startup>2</load-on-startup> </servlet>

ContorlSysInfoAction.java

程序代碼

public class ContorlSysInfoAction extends TychoAction {     public ActionForward execute(ActionMapping mapping, ActionForm form,             HttpServletRequest request, HttpServletResponse response) {         try {             javax.servlet.ServletConfig config = this.getServlet().getServletConfig();             System.out.println("******" + config.getInitParameter("config"));         } catch (Exception ex) {}         return mapping.findForward("success");     } }

根據使用的框架不同，取得方法都不僅相同。這裏僅僅列出幾種較常用的方法供大家參考。