Filter用户例子

原创文章,鼓励转载请务必注明出处,作者:李佳

最近项目中需要转换路径,把访问/m ,/m/,/m/* 的连接分发到三种不同类型的手机中,解决方法是使用Filter,在进入Servlet之前进行拦截,之后改变显示路径相关代码如下:

package common.util.mobile;

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 javax.servlet.http.HttpSession;

import common.init.InitParam;

public class MoblieFilter implements Filter{

 protected FilterConfig filterConfig;
 
 public void destroy() {
 }

 public void doFilter(ServletRequest request, ServletResponse response,
            FilterChain chain) throws IOException, ServletException {
  try{
  HttpServletRequest httpRequest = (HttpServletRequest)request;
  HttpServletResponse httpResponse = (HttpServletResponse)response;
  String requestURL = httpRequest.getRequestURI();
  InitParam.DebugLog("[doFilter:] Coming URL:" + requestURL);
  String replacement = "/i/";
  if(requestURL.equals("/m/") ||requestURL.equals("/m")){
   httpRequest.getRequestDispatcher(httpResponse.encodeURL("/m/index.servlet?moblie=true")).forward(request, response);
   //httpResponse.sendRedirect(httpResponse.encodeRedirectURL("/m/index.servlet?moblie=true"));
  } else
  {
   int mobiletype = Carrier.recognize(httpRequest);
   if(mobiletype == Carrier.IMODE){
    replacement = "/i/";      
   }else if(mobiletype == Carrier.JSKY){
    replacement = "/j/";      
   }else if(mobiletype == Carrier.EZWEB){
    replacement = "/e/";      
   }
   InitParam.DebugLog("[doFilter:] Final URL:" + requestURL.replaceFirst("/m/",replacement));
   httpRequest.getRequestDispatcher(requestURL.replaceFirst("/m/",replacement)+"?moblie=true").forward(request, response);
   //httpResponse.sendRedirect(httpResponse.encodeRedirectURL(requestURL.replaceFirst("/m/",replacement)+"?moblie=true"));
  }
  chain.doFilter(request, response);
  }catch (Exception e) {
   
  }
 }

 public void init(FilterConfig filterConfig) throws ServletException {
     this.filterConfig = filterConfig;

 }
}

在web.xml中加入如下配置:

<filter>
  <filter-name>mobilefilter</filter-name>
  <filter-class>common.util.mobile.MoblieFilter</filter-class>
 </filter>
 <filter-mapping>
  <filter-name>mobilefilter</filter-name>
  <url-pattern>/m/</url-pattern>
 </filter-mapping>
 <filter-mapping>
  <filter-name>mobilefilter</filter-name>
  <url-pattern>/m</url-pattern>
 </filter-mapping>
 <filter-mapping>
  <filter-name>mobilefilter</filter-name>
  <url-pattern>/m/*</url-pattern>
 </filter-mapping>