AJAXリクエスト未登録およびセッション失効の解決策

1.AJAXリクエスト未登録およびセッション失効の解決策

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
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;


/**
 *      
 *　　  Session           2     
 *　　   ajax     session  
 * @author Merlin.Ma
 *
 */
 public class LoginFilter implements Filter{

private String redirectUrl = "/login.html";
private String sessionKey = "userName";

@Override
public void destroy() {
}

@Override
public void doFilter(ServletRequest request, ServletResponse response,
        FilterChain chain) throws IOException, ServletException {
    
    HttpServletRequest req = (HttpServletRequest) request;
    HttpServletResponse rep = (HttpServletResponse) response;
    
    HttpSession session = req.getSession();
    
    if( session == null || session.getAttribute(sessionKey) == null){
        //      AJAX   ,     session  
        if( req.getHeader("x-requested-with") != null && req.getHeader("x-requested-with").equals("XMLHttpRequest")  ) {
        
            rep.setHeader("sessionstatus", "timeout"); 
            
        } else {
            rep.sendRedirect( req.getContextPath() + redirectUrl);
        }
        
    }else {
        chain.doFilter(request, response);
    }      
}

@Override
public void init(FilterConfig filterConfig) throws ServletException {
    
    String url = filterConfig.getInitParameter("redirectUrl");
    String key = filterConfig.getInitParameter("sessionKey");
    
    redirectUrl = url == null? redirectUrl:url;
    sessionKey = key == null ? sessionKey : key ;
}


}

//グローバルなajaxアクセス、ajaxリクエスト処理時のsesionタイムアウト、jsコードはconfig.jsの構成、または共通に導入されたjsに直接貼り付けられます.

	$.ajaxSetup({
	    contentType : "application/x-www-form-urlencoded;charset=utf-8",
	    complete : function(XMLHttpRequest, textStatus) {
	        var sessionstatus = XMLHttpRequest.getResponseHeader("sessionstatus"); //   XMLHttpRequest     ，sessionstatus，
	        if (sessionstatus == "timeout") {
	            //         ，        
	            window.location.replace("login.html");
	        }
	    }
	});