Filter中排除对指定URL的过滤

时间 2019-12-11

原文原文链接

1. 咱们能够在web.xml中配置filter来对指定的URL进行过滤，进行一些特殊操做如权限验证等。html

<!– session过滤filter –>
<filter>
    <filter-name>SessionFilter</filter-name>
    <filter-class>com.xm.chris.SessionFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>SessionFilter</filter-name>
    <url-pattern>/resources/*</url-pattern>
</filter-mapping>

public class SessionFilter implements Filter {
    private static final String CONTENT_TYPE = "text/html; charset=UTF-8";
    private FilterConfig _filterConfig = null;

    public void init(FilterConfig filterConfig) throws ServletException {
        _filterConfig = filterConfig;
    }

    public void destroy() {
        _filterConfig = null;
    }

    public void doFilter(ServletRequest request, ServletResponse response,
                         FilterChain chain) throws IOException,
            ServletException {
        HttpServletRequest rq = (HttpServletRequest) request;
        HttpSession httpSession = rq.getSession();
        Long userId = (Long) httpSession.getAttribute("userId");
        if (userId == null) {
            response.setContentType(CONTENT_TYPE);
            PrintWriter out = response.getWriter();
            out.println("<html>");
            out.println("<head><title>Error</title></head>");
            out.println("<body>");
            out.println("<p id='Message'>错误.</p>");
            out.println("</body></html>");
            out.close();
        } else {
            chain.doFilter(request, response);
        }

    }
}

这时全部请求了contextPath/resources/*路径的request都会被SessionFilter验证是否登陆。web

2. 可是咱们有一些特定的url不想验证登陆，想要直接可以访问，怎么办呢？服务器

这时能够配置一个参数，告诉Filter哪些url不想验证。session

<filter>
    <filter-name>SecurityFilter</filter-name>
    <filter-class>com.oracle.ccsc.jcs.sx.filter.SecurityFilter</filter-class>
    <init-param>
        <param-name>excludedPages</param-name>
        <param-value>/xm/portal/notice</param-value>
    </init-param>
</filter>

而后在Filter中就能够根据参数判断是否须要过滤。oracle

public class SecurityFilter implements Filter {
    private static final String CONTENT_TYPE = "text/html; charset=UTF-8";
    private FilterConfig _filterConfig = null;

    private String excludedPages;
    private String[] excludedPageArray;

    public void init(FilterConfig filterConfig) throws ServletException {
        _filterConfig = filterConfig;

        excludedPages = filterConfig.getInitParameter("excludedPages");
        if (StringUtils.isNotEmpty(excludedPages)) {
            excludedPageArray = excludedPages.split(",");
        }
    }

    public void destroy() {
        _filterConfig = null;
    }

    public void doFilter(ServletRequest request, ServletResponse response,
                         FilterChain chain) throws IOException,
            ServletException {
        HttpServletRequest rq = (HttpServletRequest) request;
  
        boolean isExcludedPage = false;
        for (String page : excludedPageArray) { //判断是否在过滤url以外if (rq.getPathInfo().equals(page)) {
                isExcludedPage = true;
                break;
            }
        }
        if (isExcludedPage) { //在过滤url以外
            chain.doFilter(request, response);
        } else { //不在过滤url以外，判断登陆
            HttpSession httpSession = rq.getSession();
            Long userId = (Long) httpSession.getAttribute("userId");
            if (userId == null) {
                response.setContentType(CONTENT_TYPE);
                PrintWriter out = response.getWriter();
                out.println("<html>");
                out.println("<head><title>Error</title></head>");
                out.println("<body>");
                out.println("<p id='Message'>错误.</p>");
                out.println("</body></html>");
                out.close();
            } else {
                chain.doFilter(request, response);
            }
        }
    }
}

3. 关于用Servlet获取URL地址。app

在HttpServletRequest类里，有如下六个取URL的函数函数

getContextPath 取得项目名
getServletPath 取得Servlet名
getPathInfo 取得Servlet后的URL名，不包括URL参数
getRequestURL 取得不包括参数的URL
getRequestURI 取得不包括参数的URI，即去掉协议和服务器名的URL url

具体以下图：spa

相对应的函数的值以下：

getContextPath：/ServletTest
getServletPath：/main
getPathInfo：/index/testpage/test
getRequestURL：http://localhost:8080/ServletTest/main/index/testpage/test
getRequestURI：/ServletTest/main/index/testpage/test code