判断是否登录的拦截器SessionFilter

需要写个拦截器，当用户没有登录的时候某些页面是不能访问的
用法将需要登录后访问的文件全部放在一个文件夹中，这里是logined文件夹

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;

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 com.tlt.app.bean.Useraccount;
import com.tlt.app.util.Constants;

public class SessionFilter implements Filter{
	private List list = new ArrayList();
	
	public void destroy() {
		// TODO Auto-generated method stub
	}

	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		// TODO Auto-generated method stub
		String path=((HttpServletRequest)request).getServletPath();
//		System.out.println("path="+path);
		for(int i=0;i<list.size();i++){
			if(path.indexOf((String)list.get(i))!=-1){//需要拦截
				if (((HttpServletRequest) request).getSession().getAttribute(Constants.USER_KEY) == null) {//session不存在需要拦截
					String contextPath=((HttpServletRequest)request).getContextPath();
//					System.out.println("ContextPath="+contextPath);
					((HttpServletResponse)response).sendRedirect(contextPath+"/login.jsp?toPath="+servletPath);//记录下登录后需要跳转到的页面，比如：/logined/account.jsp
				}else{
					chain.doFilter(request, response);
				}
				break;
			}else{
				chain.doFilter(request, response);
			}
		}
		
	}

	public void init(FilterConfig filterConfig) throws ServletException {
		// TODO Auto-generated method stub
		 //初始化需要拦截的文件夹
		 String include = filterConfig.getInitParameter("include");
		 if (include != null) {
				StringTokenizer st = new StringTokenizer(include, ",");
				list.clear();
				while (st.hasMoreTokens()) {
					list.add(st.nextToken());
				}
		 }
		
	}

}

可以使用多个文件夹，只需要将<param-value>中的值之间用“,”隔开。

<filter>
		<filter-name>sessionFilter</filter-name>
		<filter-class>com.tlt.app.filter.SessionFilter</filter-class>
		<init-param>
			<param-name>include</param-name>
			<param-value>logined</param-value>
		</init-param>
	</filter>
	<filter-mapping>
		<filter-name>sessionFilter</filter-name>
		<url-pattern>/*</url-pattern>
	</filter-mapping>

<session-config>
<session-timeout>30 </session-timeout>
</session-config>

来指定30分钟超时