用过滤器Filter判断用户是否登陆

用过滤器Filter判断用户是否登陆

WEB.XML

1. <!-- 用户session的 键   sessionKEY -->
2. <context-param>
3. <param-name>userSessionKey</param-name>
4. <param-value>USERSESSIONKEY</param-value>
5. </context-param>
6. <!-- 重定向的页面 -->
7. <context-param>
8. <param-name>rediretPage</param-name>
9. <param-value>/u_member/Login.jsp</param-value>
10. </context-param>
11. <!-- 不需要过滤的页面 -->
12. <context-param>
13. <param-name>uncheckUrls</param-name>
14. <param-value>/u_member/insert.jsp,/u_member/Login.jsp</param-value>
15. </context-param>

Filter 过滤器代码

1. package go.onlineShop.filter;
2. import java.io.IOException;
3. import java.util.Arrays;
4. import java.util.List;
5. import javax.servlet.Filter;
6. import javax.servlet.FilterChain;
7. import javax.servlet.FilterConfig;
8. import javax.servlet.ServletException;
9. import javax.servlet.ServletRequest;
10. import javax.servlet.ServletResponse;
11. import javax.servlet.annotation.WebFilter;
12. import javax.servlet.http.HttpServletRequest;
13. import javax.servlet.http.HttpServletResponse;
14. /**
15. * Servlet Filter implementation class IsLoginFilter
16. * 判断是否登陆过滤器
17. */
18. @WebFilter("/u_member")
19. public class IsLoginFilter implements Filter {
20. //从xml中取值
21. String uncheckUrls =null;
22. String userSessionKey=null;
23. String rediretPage=null;
24. /**
25. * Default constructor.
26. */
27. public IsLoginFilter() {
28. // TODO Auto-generated constructor stub
29. }
30. /**
31. * @see Filter#destroy()
32. */
33. public void destroy() {
34. // TODO Auto-generated method stub
35. }
36. /**
37. * @see Filter#doFilter(ServletRequest, ServletResponse, FilterChain)
38. */
39. public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
40. // TODO Auto-generated method stub
41. //1.得到访问路径
42. HttpServletRequest request = (HttpServletRequest)req;
43. HttpServletResponse response = (HttpServletResponse)res;
44. String reqUrl = request.getRequestURL().toString();
45. String reqURI = request.getRequestURI();
46. String servletPath = request.getServletPath();
47. //  String[] uncheckUrl = uncheckUrls.split(",");
48. List<String> urls = Arrays.asList(uncheckUrls.split(","));
49. //2.如果是属于不需要过滤的地址就直接  放行  方法结束
50. if(urls.contains(servletPath)){
51. chain.doFilter(request, response);
52. return;
53. }
54. //3.从session中获取sessionKey对应的值；若不存在  则跳转到登陆页面
55. Object user = request.getSession().getAttribute(userSessionKey);
56. if(user==null){
57. request.getRequestDispatcher(rediretPage).forward(request, response);
58. return;
59. }
60. //4若存在 则放行；
61. chain.doFilter(request, response);
62. }
63. /**
64. * @see Filter#init(FilterConfig)
65. */
66. public void init(FilterConfig fConfig) throws ServletException {
67. rediretPage=fConfig.getServletContext().getInitParameter("rediretPage");
68. uncheckUrls=fConfig.getServletContext().getInitParameter("uncheckUrls");
69. userSessionKey=fConfig.getServletContext().getInitParameter("userSessionKey");
70. }
71. }

Login页面

参考：

用过滤器Filter判断用户是否登陆 - CSDN博客
http://blog.csdn.net/u010634066/article/details/38769577