java登录拦截Filter

此例子为一个简单的登录拦截。

首先在web.xml中配置拦截类。

<filter-mapping>
        <filter-name>SessionFilter</filter-name>
        <url-pattern>/*</url-pattern>
        <dispatcher>REQUEST</dispatcher>
    </filter-mapping>
<filter>
    <filter-name>SessionFilter</filter-name>
    <!-- 拦截类 -->
    <filter-class>com.skin.generate.user.UserLoginFilter</filter-class>
    <init-param>
        <param-name>loginUrl</param-name>
        <param-value>/finder/login.html</param-value>
    </init-param>
    <!-- 配置参数 比如不拦截的路径 -->
    <init-param>
        <param-name>excludes</param-name>
        <param-value>
            /register.html,
            /resource/**/*,
            /note/**/*
        </param-value>
    </init-param>
</filter> 

其次就是拦截类的编写。

package com.skin.generate.user;
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.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import com.skin.finder.security.UserSession;
import com.skin.finder.web.util.Client;
import com.skin.finder.web.util.CookieUtil;
import com.skin.generate.entity.User;

public class UserLoginFilter implements Filter {
/*
     * String nofilter; String nofilterFiles[]; String sendRedirect;
     */

    public void destroy() {

    }

    public void doFilter(ServletRequest req, ServletResponse res,
            FilterChain chain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) res;
        String path = request.getServletPath();
        String url = request.getRequestURI();

        // 如果不需要过滤的静态文件，直接放行
        if (path.endsWith(".css") || path.endsWith(".js")
                || path.endsWith("Login.html")
                || url.indexOf("resource") > 0 || url.indexOf("note") > 0
                || url.endsWith("login.jsp") || path.endsWith(".gif")
                || path.endsWith(".ico")) {
            chain.doFilter(request, response);
            return;
        } else {
            if (checkUser(request, response)) {
                chain.doFilter(request, response);// 如果用户已经登录，就放行
                return;
            } else {
                // 没有登录，重定向到登录页面
                String contextPath = getContextPath(request);
                response.sendRedirect(contextPath+ "/template/finder/login.jsp");
                return;
            }
        }

    }

    protected String getContextPath(HttpServletRequest request) {
        String contextPath = request.getContextPath();

        if ((contextPath == null) || (contextPath.equals("/"))) {
            return "";
        }
        return contextPath;
    }

    private boolean isInArray(String path, String nofilterFiles[]) {
        for (int i = 0; i < nofilterFiles.length; i++) {
            String nofilterFile = nofilterFiles[i];
            if (nofilterFile.equals(path)) {
                return true;
            }
        }
        return false;
    }

    private boolean checkUser(HttpServletRequest request,
            HttpServletResponse response) throws IOException {

        //1.判断cookie 是否存在
        Cookie cookie = CookieUtil.getCookie(request, Client.COOKIE_NAME);
        if(cookie ==null ){
            return false;
        }

        //2.校验session
        HttpSession session = request.getSession(false);// 如果不存在返回空
        if (session == null) {
            return false;
        }
        //3.校验登录用户
        Object obj = session.getAttribute(SessionUtils.USER_NAME);
        if (obj == null) {
            return false;
        }

        return true;
    }

    public void init(FilterConfig config) throws ServletException {
        /*
         * nofilter = config.getInitParameter("excludes");
         * nofilterFiles =nofilter.split(","); sendRedirect =
         * config.getInitParameter("loginUrl");
         */
        // System.out.println(Arrays.asList(nofilterFiles));
    }

}