使用Filter封装一个请求

import Javax.servlet.Filter;

import javax.servlet.FilterChain;

import javax.servlet.FilterConfig;

import javax.servlet.ServletContext;

import javax.servlet.ServletException;

import javax.servlet.ServletRequest;

import javax.servlet.ServletResponse;

import javax.servlet.http.HttpServletRequest;

public class RequestFilter implements Filter {

private FilterConfig config;

/** Creates new RequestFilter */

public RequestFilter() {

}

public void init(FilterConfig filterConfig) throws ServletException {

this.config = filterConfig;

}

public void doFilter(ServletRequest request, ServletResponse response,

FilterChain chain) throws java.io.IOException, ServletException {

ReqWrapper wrapper = null;

ServletContext context = null;

if (request instanceof HttpServletRequest)

wrapper = new ReqWrapper((HttpServletRequest) request);

/*

* use the ServletContext.log method to log param names/values

*/

if (wrapper != null) {

context = config.getServletContext();

context.log("Query: " + wrapper.getQueryString());

}

//continue the request, response to next filter or servlet

//destination

if (wrapper != null)

chain.doFilter(wrapper, response);

else

chain.doFilter(request, response);

}

public void destroy() {

/*

* called before the Filter instance is removed from service by the web

* container

*/

}

}

（出处：http://www.knowsky.com）