登陆安全过滤器

新建SecurityFilter.java

package org.thj.bookstore.util;
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 javax.servlet.http.HttpServletResponse;

public class SecurityFilter implements Filter {

    public void destroy() {
    }

    public void doFilter(ServletRequest req, ServletResponse res,
            FilterChain chain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest)req;
        HttpServletResponse response = (HttpServletResponse)res;
        if(request.getSession().getAttribute("user")==null){
           
            String path = request.getContextPath();
//没有登陆就跳到index.jsp
            response.sendRedirect(path + "/index.jsp");
        }
        else{
           
            chain.doFilter(request,response);
        }
    }

    public void init(FilterConfig arg0) throws ServletException {
        // TODO Auto-generated method stub

    }

}

在web.xml中注册：   

<filter>
        <filter-name>securityFilter</filter-name>
        <filter-class>org.thj.bookstore.util.SecurityFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>securityFilter</filter-name>
        <url-pattern>/jsp/*</url-pattern>
    </filter-mapping>
<!--只过滤jsp目录下的所以页面-->
<filter-mapping>
        <filter-name>userlogin</filter-name>
        <url-pattern>/jsp/user/*</url-pattern>
    </filter-mapping>
    <filter-mapping>
        <filter-name>userlogin</filter-name>
        <url-pattern>/jsp/ques/*</url-pattern>
    </filter-mapping>