package com.struts2.filter;import java.io.IOException;import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import com.struts2.action.Action;
import com.struts2.action.HelloWorldAction;
import com.struts2.utils.ServletUtils;public class DispatchFilter implements Filter {private HttpServletRequest request;private HttpServletResponse response;@Overridepublic void destroy() {// TODO Auto-generated method stub}@Overridepublic void doFilter(ServletRequest request, ServletResponse response,FilterChain arg2) throws IOException, ServletException {/*** 1.先获取HttpServletRequest,HttpServletResponse* 2.获取HelloWorldAction.action中的HelloWorldAction* 3.利用java的反射机制进行调用*/this.request=(HttpServletRequest) request;this.response=(HttpServletResponse) response;String requestURI = this.request.getRequestURI();System.out.println(requestURI);String actionName = ServletUtils.convert(requestURI);//利用java的反射机制调用该方法try {//利用java反射机制创建一个新的HelloWorldAction对象HelloWorldAction action = (HelloWorldAction) Class.forName("com.struts2.action."+actionName).newInstance();String forward = action.execute(this.request, this.response);/*** 2种跳转方法*  *重定向*    request里的参数不起作用*    this.response.sendRedirect(jsp页面)*  *转发*    放在  request中的值可以取出来*    this.request.getRequestDispatcher("index.jsp").forward(this.request, this.response);*  */this.request.getRequestDispatcher("index.jsp").forward(this.request, this.response);} catch (InstantiationException e) {e.printStackTrace();} catch (IllegalAccessException e) {e.printStackTrace();} catch (ClassNotFoundException e) {e.printStackTrace();}}@Overridepublic void init(FilterConfig arg0) throws ServletException {}}

  <filter><filter-name>DispatchFilter</filter-name><filter-class>com.struts2.filter.DispatchFilter</filter-class></filter><filter-mapping><filter-name>DispatchFilter</filter-name><url-pattern>*.action</url-pattern></filter-mapping>

    <a href="HelloWorldAction.action">请求一个action</a>

package com.struts2.action;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;public class HelloWorldAction implements Action {@Overridepublic String execute(HttpServletRequest request,HttpServletResponse response) {System.out.println("Hello World Struts2");return "index.jsp";}}

/*** 2种跳转方法*  *重定向*      request里的参数不起作用*    this.response.sendRedirect(jsp页面)*  *转发*    放在  request中的值可以取出来*    this.request.getRequestDispatcher("index.jsp").forward(this.request, this.response);*  */this.request.getRequestDispatcher("index.jsp").forward(this.request, this.response); // 这句话的意思是，上面返回了一个字符串"index.jsp"，那么这里就是去寻找这个index.jsp，并将request和response放进去。