配置过滤器
配置过滤器，通过mapping的url-pattern将访问页面截住,通过import javax.servlet.Filter来进行一些校验处理，
,实现innt(),doFilter(),destory()然后转向页面
? 代码：
? public class AccessFilter extends HttpServlet implements Filter {
????? private FilterConfig filterConfig;? //Handle the passed-in FilterConfig
?? private String loginPage;
????? private String[] pageBeforeLogin;
????? private final String[] DEFAULT_LOGIN_PAGE={"/login.jsp"};
????? /**
?????? * 获取InitParameter
?????? * 登录页、不用登录就可以访问的页
?????? * @param filterConfig FilterConfig
?????? * @throws ServletException
?????? */
????? public void init(FilterConfig filterConfig) throws ServletException {
??????? this.filterConfig = filterConfig;
??? try
??????? {
????????? loginPage=filterConfig.getInitParameter("loginPage");
??????? }
??????? catch(java.lang.Exception e)
??????? {
????????? loginPage=DEFAULT_LOGIN_PAGE[0];
??????? }
??????? try
??????? {
????????? pageBeforeLogin=(loginPage + "," + filterConfig.getInitParameter("pageBeforeLogin")).split(",");
??????? }
??????? catch(Exception e)
??????? {
??????? }
????? }
????? //Process the request/response pair
????? public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) {
??????? HttpServletRequest req=(HttpServletRequest) request;
??????? HttpServletResponse res=(HttpServletResponse) response;
??????? //先判断是否已经登录
?
?????????? HttpSession session= req.getSession();
?????????? if(session!=null&&session.getAttribute(SystemGlobals.LOGINUSERID)!=null){
??????????????? doNext(request, response, filterChain);
?????????????? return;
?????????? }
?????????? //clientRequest 记录真正的被请求的 URL 比如 /index.jsp;/login.jsp;/
?????????? String clientRequest = req.getServletPath();
?????????? System.out.println(clientRequest);
?????????? for (int i=0;i<pageBeforeLogin.length;i++)
?????????? {
???????????? if (pageBeforeLogin[i].equalsIgnoreCase(clientRequest))
???????????? {
??????????????? doNext(request,response,filterChain);
??????????????? return;
???????????? }
?????????? }
????? //运行到此处说明必须转到登录界面
??????? try
??????? {
?????????? //RequestDispatcher rd = this.filterConfig.getServletContext().getRequestDispatcher(loginPage); // req.getRequestDispatcher(loginPage);
?????????? //rd.forward(request, res);
??????????? res.sendRedirect(req.getContextPath()+ loginPage);
??????????? return;
??????? }
??????? catch(Exception e)
??????? {
????????? e.printStackTrace();
??????? }
????? }
???? private void doNext(ServletRequest request, ServletResponse response, FilterChain filterChain)
???? {
?????? try {
????????????? filterChain.doFilter(request, response);
??????????? }
??????????? catch(ServletException sx) {
????????????? filterConfig.getServletContext().log(sx.getMessage());
??????????? }
??????????? catch(IOException iox) {
????????????? filterConfig.getServletContext().log(iox.getMessage());
??????????? }
???? }
????? //Clean up resources
????? public void destroy() {
????? }
}
? web.xml配置：
? <filter>
??? <filter-name>sessionloginchecker</filter-name>
??? <filter-class>com.itsv.chy.system.permission.AccessFilter</filter-class>
??? <init-param>
????? <param-name>loginPage</param-name>
????? <param-value>/system/login.jsp</param-value>
??? </init-param>
??? <init-param>
????? <param-name>pageBeforeLogin</param-name>
????? <param-value>/login.do,/logout.do</param-value>
??? </init-param>
? </filter>
? <filter-mapping>
??? <filter-name>sessionloginchecker</filter-name>
??? <url-pattern>index.jsp</url-pattern>
? </filter-mapping>
? <filter-mapping>
??? <filter-name>sessionloginchecker</filter-name>
??? <url-pattern>/accessAction.do</url-pattern>
? </filter-mapping>
