如何将调度程序配置为在会话为空或超时时重定向到主页

Question

我正在使用Spring Mvc 3.x版本。我不想在每一页上都写一个if检查。相反，我需要 Spring 内部支持的代码

Answer 1

过滤器最适合这种用例。您可以拦截每个请求并检查是否存在活动会话

import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
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;

public class AuthenticationFilter implements Filter {
    private ServletContext context;
    public void init(FilterConfig fConfig) throws ServletException {
        this.context = fConfig.getServletContext();
        this.context.log("AuthenticationFilter initialized");
    }
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) request;
        HttpServletResponse res = (HttpServletResponse) response;
        HttpSession session = req.getSession(false);
        if (session == null) {   //checking whether the session exists
            this.context.log("Unauthorized access request");
            res.sendRedirect(req.getContextPath() + "/loginPage.html");
        } else {
            // pass the request along the filter chain
            chain.doFilter(request, response);
        }
    }
    public void destroy() {
        //close any resources here
    }
}

此示例取自 https://medium.com/@kasunpdh/session-management-in-java-using-servlet-filters-and-cookies-7c536b40448f。有关详细信息，请查看文章。

Answer 2

在 web 中添加过滤器.xml例如：

<filter>
    <filter-name>SessionFilter</filter-name>
    <filter-class>
        com.java.util.SessionFilter
    </filter-class>
    <init-param>
        <param-name>avoid-urls</param-name>
        <param-value>/Page1.htm</param-value>
    </init-param>
</filter>
<filter-mapping>
    <filter-name>SessionFilter</filter-name>
    <url-pattern>*.htm</url-pattern>
</filter-mapping>

筛选器实现可能类似于 -

    public class FilterTest implements Filter {
    ...
    private ArrayList<String> urlList;    
    public void doFilter(ServletRequest req, ServletResponse res,
                FilterChain chain) throws IOException, ServletException {
            HttpServletRequest request = (HttpServletRequest) req;
            HttpServletResponse response = (HttpServletResponse) res;
            String url = request.getServletPath();
            boolean allowedRequest = false;
            if (urlList.contains(url)) {
                allowedRequest = true;
            }
            if (!allowedRequest) {
                HttpSession session = request.getSession(false);
                if (null == session) {
                    response.sendRedirect("startup.jsp");
                } else {
                    chain.doFilter(request, response);
                }
            } else {
                chain.doFilter(request, response);
            }
        }
        public void init(FilterConfig config) throws ServletException {
            String urls = config.getInitParameter("avoid-urls");
            StringTokenizer token = new StringTokenizer(urls, ",");
            urlList = new ArrayList<String>();
            while (token.hasMoreTokens()) {
                urlList.add(token.nextToken());
            }
}