logincheck.java

jsp编程的源代码

package com.myfilter;

import java.io.IOException;
import java.io.PrintWriter;

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;

public class LoginCheck implements Filter {

	public void init(FilterConfig arg0) throws ServletException {
		// TODO 自动生成方法存根

	}

	public void doFilter(ServletRequest arg0, ServletResponse arg1,
			FilterChain arg2) throws IOException, ServletException {
		HttpServletRequest request = (HttpServletRequest) arg0;
		HttpServletResponse response = (HttpServletResponse) arg1;
		HttpSession session = request.getSession();
		String flag = (String) session.getAttribute("flag");
		response.setCharacterEncoding("GBK");
		PrintWriter out = response.getWriter();
		if (flag.equals("0")) {
			out.print("<script language='javascript' type='text/javascript'>alert('您还没登陆,不能访问!')</script><A href='index.jsp' target='_top'>返回主页</A>");
			return;
		} else {
			arg2.doFilter(arg0, arg1);
		}
	}

	public void destroy() {
		// TODO 自动生成方法存根

	}

}