Javaweb未登录被filter过滤，过滤后重定向到登录页面，然后登录后就不放行被过滤的页面了该怎么办

Question

Javaweb
未登录被filter过滤，过滤后重定向到登录页面，然后登录后就不放行被过滤的页面了该怎么办

```java
package filter;


import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
import java.io.IOException;

public class LoginCheckFilter implements Filter {
    private String excludedPages;
    private String[] excludedPageArray;
    @Override
    public void init(FilterConfig config) throws ServletException {
        excludedPages = config.getInitParameter("excludedPages");
        if (null != excludedPages && excludedPages.length() > 0) {
            excludedPageArray = excludedPages.split(",");
        }
        return;
    }
    @Override
    public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {
        boolean isExcludedPage = false;
        HttpSession session = ((HttpServletRequest) req).getSession();
        Object user = session.getAttribute("user");
        System.out.println("user"+user);
        // 获取不过滤的列表
        for (String page : excludedPageArray) {
            if (((HttpServletRequest) req).getServletPath().equals(page)) {
                isExcludedPage = true;
                break;
            }
        }
        if (isExcludedPage) { //如果有不过滤的页面，放行
            chain.doFilter(req, resp);
        } else {
            if (user != null){
                chain.doFilter(req,resp);
            }else {
                ((HttpServletRequest)req).getRequestDispatcher("/first.jsp").forward(req,resp);
            }
        }

    }
    @Override
    public void destroy() {
    }
}

```

Answer 1

在Filter中，可以通过检查会话中是否存在登录状态信息来判断用户是否已登录，如果已登录，则放行请求，否则进行重定向到登录页面

public class AuthenticationFilter implements Filter {

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest httpRequest = (HttpServletRequest) request;
        HttpServletResponse httpResponse = (HttpServletResponse) response;

        // 获取当前会话
        HttpSession session = httpRequest.getSession(false);

        // 检查会话中是否存在登录状态信息
        if (session != null && session.getAttribute("loggedIn") != null) {
            // 用户已登录，放行请求
            chain.doFilter(request, response);
        } else {
            // 用户未登录，重定向到登录页面
            httpResponse.sendRedirect(httpRequest.getContextPath() + "/login");
        }
    }

    // 省略其他方法
}