messagefilter.java

STRUTS数据库项目开发宝典

package com.relationinfo.webapp.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 org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Filter to remove messages form the session and put them in the request
 * - to solve the redirect after post issue.
 * 
 * <p><a href="MessageFilter.java.html"><i>www.relationinfo.com</i></a></p>
 *
 * @author  cao guangxin
 *
 * @web.filter display-name="Message Filter" name="messageFilter"
 */
public class MessageFilter implements Filter {
    private static Log log = LogFactory.getLog(MessageFilter.class);

    public void doFilter(ServletRequest req, ServletResponse res,
                         FilterChain chain)
    throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) req;

        // grab messages from the session and put them into request
        // this is so they're not lost in a redirect
        Object messages = request.getSession().getAttribute("messages");

        if (messages != null) {
            request.setAttribute("messages", messages);
            request.getSession().removeAttribute("messages");
        }
        
        // grab errors from the session and put them into request
        // this is so they're not lost in a redirect
        Object errors = request.getSession().getAttribute("errors");

        if (errors != null) {
            request.setAttribute("errors", errors);
            request.getSession().removeAttribute("errors");
        }

        chain.doFilter(req, res);
    }

    public void init(FilterConfig filterConfig) {
    }

    public void destroy() {
    }
}