loginfilter.java

精通Java核心技术源代码

// ==================== Program Discription =====================
// 程序名称：示例14-8 : LoginFilter.java
// 程序目的：学习使用过滤器
// ==============================================================
import javax.servlet.FilterChain;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.ServletException;
import javax.servlet.FilterConfig;


public class LoginFilter implements Filter
{
	String LOGIN_PAGE="init.jsp";
	protected FilterConfig filterConfig;
	public void doFilter(final ServletRequest req,final ServletResponse res,FilterChain chain)throws IOException,ServletException
	{
		 HttpServletRequest hreq = (HttpServletRequest)req;
         HttpServletResponse hres = (HttpServletResponse)res;	
         String isLog=(String)hreq.getSession().getAttribute("isLog");	 
		 if((isLog!=null)&&((isLog.equals("true"))||(isLog=="true")))//检查是否登陆
		 {
		 	chain.doFilter(req,res);
		 	return ;
		 }
		 else
		 	hres.sendRedirect(LOGIN_PAGE);		 	
	}
	
	public void destroy()
	{
		this.filterConfig=null;
	}
	public void init(FilterConfig config)
	{
		this.filterConfig=config;
	}
	public void setFilterConfig(final FilterConfig filterConfig)
	{
		this.filterConfig=filterConfig;
	}
	
}