java拦截通过url访问页面，必须通过登录页面访问目标页面

在web.xml中配置过滤：

    <filter>
        <filter-name>LoginFilter</filter-name>
        <filter-class>com.verification.action.LoginFilter</filter-class>
    </filter>

    <filter-mapping>
        <filter-name>LoginFilter</filter-name>
        <url-pattern>y/form/dealParse.do</url-pattern>
    </filter-mapping>

/*  拦截所有请求

/.do   拦截以“.do”结尾的请求

/index.jsp  拦截指定的jsp

/artery/form/*  拦截该目录下的所有请求

等等

拦截器，拦截请求类：

思路：比较“由登录页面登录后的session中属性值”和“通过url直接访问的session中的属性值”，找到其中不一样的，这就是判断依据。（判断依据可以参考登录逻辑类的代码）

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;
import javax.servlet.http.HttpSession;

/**
 * 主页面拦截,必须从登陆页面进入index
 */
public class LoginFilter implements Filter {
    @Override
    public void destroy() {

    }

    @Override
    public void doFilter(ServletRequest servletRequest,
            ServletResponse servletResponse, FilterChain chain) throws IOException, ServletException {

        HttpServletRequest request = (HttpServletRequest) servletRequest;
        HttpServletResponse response = (HttpServletResponse) servletResponse;

        HttpSession hs = request.getSession();
        if ("ture".equals(hs.getAttribute("isLogin"))) {//登录后，进入session查看session中的登录状态找到判断依据，
            chain.doFilter(request, response);
            return;
        }

        response.sendRedirect(request.getContextPath() + "/login.jsp");
    }

    @Override
    public void init(FilterConfig arg0) throws ServletException {

    }

}

登录逻辑代码：

import javax.crypto.spec.DESedeKeySpec;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import com.thunisoft.artery.module.config.ArteryConfigUtil;

/**
 * 登录页身份认证
 * @author sunwenhao
 */
public class IdentityVerificationAction extends Action {
    
    private final Log logger = LogFactory.getLog(IdentityVerificationAction.class);
    
    private static final String IS_LOGIN_KEY = "isLogin";//在此处设置了登录的判断属性

    private static final String IS_LOGIN_VALUE = "ture";//在此处设置了登录的属性的判断初始属性
    
    private static final String SEC_STR="Hso2ThxNiSofHso2ThxNiSof";
    
    @Override
    public ActionForward execute(ActionMapping mapping, ActionForm form,
            HttpServletRequest request, HttpServletResponse response)
            throws Exception {
        
        IdentityBean identityInfo = (IdentityBean)form;
        
        boolean success = verificationInfo(identityInfo);
        
        //如果验证身份成功或者不使用登录页
        if(success) {
            request.getSession().setAttribute(IS_LOGIN_KEY, IS_LOGIN_VALUE);
            return mapping.findForward("success");
        }    
        
        request.setAttribute("msg", "用户名或密码错误");
        
        return mapping.findForward("fail");
    }
    
    /**
     * 是否登录
     * 
     * @param request
     * @param response
     * 
     * @return
     */
    public static boolean isLogin(HttpServletRequest request, HttpServletResponse response) {
        
        String isLogin = (String)request.getSession().getAttribute(IS_LOGIN_KEY);
        
        return IS_LOGIN_VALUE.equals(isLogin);
    }
    
    
    /**
     * 验证登录信息
     * 
     * @param request
     * @param response
     * 
     * @return
     */
    private boolean verificationInfo(IdentityBean identityInfo) {
        
        String user = identityInfo.getUsername();
        String pwd = identityInfo.getPassword();
        
        pwd=CryptUtil.encrypt(CryptFactory.ALGORITHM_3DES, pwd, SEC_STR); 
            
        String username = ArteryConfigUtil.getProperty("username");
        String password = ArteryConfigUtil.getProperty("password");
        
        try {
            if(username.equals(user) && password.equals(pwd)) 
                return true;
            
            return false;
        } catch (Exception e) {
            logger.error("验证用户名和密码时出现错误.");
            return false;
        }
        
    }

}