Filter mapping

web.xml에 Filter클래스를 등록하고 모든 요청을 우선적으로 접수하는 예
Struts2와 같은 프레임워크의 작동방식을 이해하기 위해 작성해 본 예제

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>Hello</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>
 
  <filter>
   <filter-name>myFilter</filter-name>
   <filter-class>filter.MyFilter</filter-class>
  </filter>
 
  <filter-mapping>
   <filter-name>myFilter</filter-name>
   <url-pattern>/*</url-pattern>
  </filter-mapping>
</web-app>

MyFilter.java

package filter;

import java.io.*;
import java.lang.reflect.InvocationTargetException;

import javax.servlet.*; // Filter인터페이스가 포함된 패키지

import action.MyAction;
import interceptor.MyInterceptor;

public class MyFilter implements Filter {

 @Override
 public void destroy() {
  // TODO Auto-generated method stub
  System.out.println("MyFilter destroy()");
 }

 @Override
 public void doFilter(ServletRequest request, ServletResponse response,
   FilterChain arg2) throws IOException, ServletException {
  // TODO Auto-generated method stub
  System.out.println("MyFilter doFilter()");

  MyAction action = new MyAction();
  MyInterceptor ic = new MyInterceptor();

   try {
    ic.processParam(request, action);
   } catch (Exception e) {
    e.printStackTrace();
   }

  String result = action.execute(request, response);
  if(result.equals("success")){
   RequestDispatcher rd = request.getRequestDispatcher("/view.jsp");
   rd.forward(request, response);
  }
 }

 @Override
 public void init(FilterConfig arg0) throws ServletException {
  // TODO Auto-generated method stub
  System.out.println("MyFilter init()");
 }
}