用过滤器实现比较简单:
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.util.List;
import java.util.ArrayList;
import java.util.StringTokenizer;
import java.io.IOException;
/**
* 用于检测用户是否登陆的过滤器,如果未登录,则重定向到指的登录页面 配置参数 redirectURL 如果用户未登录,则重定向到指定的页面,URL不包括
* ContextPath notCheckURLList不做检查的URL列表,以分号分开,并且 URL 中不包括 ContextPath
* checkSessionKey 需检查的在 Session 中保存的关键字
*/
public class CheckLoginFilter implements Filter {
protected FilterConfig filterConfig = null;
private String redirectURL = null;
private String sessionKey = null;
private List notCheckURLList = new ArrayList();
public void init(FilterConfig filterConfig) throws ServletException {
this.filterConfig = filterConfig;
redirectURL = filterConfig.getInitParameter("redirectURL");
sessionKey = filterConfig.getInitParameter("checkSessionKey");
String notCheckURLListStr = filterConfig
.getInitParameter("notCheckURLList");
if (notCheckURLListStr != null) {
StringTokenizer st = new StringTokenizer(notCheckURLListStr, ";");
notCheckURLList.clear();
while (st.hasMoreTokens()) {
notCheckURLList.add(st.nextToken());
}
}
}
public void doFilter(ServletRequest servletRequest,
ServletResponse servletResponse, FilterChain filterChain)
throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) servletRequest;
HttpServletResponse response = (HttpServletResponse) servletResponse;
HttpSession session = request.getSession();
if (sessionKey == null) {
filterChain.doFilter(request, response);
return;
}
if ((!checkRequestURIIntNotFilterList(request))
&& session.getAttribute(sessionKey) == null) {
response.sendRedirect(request.getContextPath() + redirectURL);
return;
}
filterChain.doFilter(servletRequest, servletResponse);
}
private boolean checkRequestURIIntNotFilterList(HttpServletRequest request) {
String uri = request.getServletPath()
+ (request.getPathInfo() == null ? "" : request.getPathInfo());
return notCheckURLList.contains(uri);
}
public void destroy() {
notCheckURLList.clear();
}
}
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