loginfilter.java

jsp,过滤器和监听器的简单例子

package MyPackage;

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.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


public class loginFilter extends HttpServlet implements Filter{

	private String login_page = null;
	private static final long serialVersionUID = 1L;

	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain filterChain) throws IOException, ServletException {
		// TODO Auto-generated method stub
		HttpServletRequest httpRequest = (HttpServletRequest)request;
		HttpServletResponse httpResponse = (HttpServletResponse)response;
		String uri = httpRequest.getRequestURI();
		String name = request.getParameter("userName");
		String pwd = request.getParameter("pwd");
		if(name != null && !name.equals("")){
			if(pwd != null && !pwd.equals("")){
				filterChain.doFilter(request, response);
			}
			else{
				httpResponse.sendRedirect("../login.jsp");
			}
		}
		else if(uri.indexOf(this.login_page) != -1 || httpRequest.getSession().getAttribute("user") != null){
			filterChain.doFilter(request, response);			
		}
		else{
			httpResponse.sendRedirect("../login.jsp");
		}
	}

	public void init(FilterConfig arg0) throws ServletException {
		// TODO Auto-generated method stub
		this.login_page = arg0.getInitParameter("login_uri");
	}

}