访问权限控制AuthFilter

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; 

import com.sino.common.Global;

public class AuthFilter implements Filter {

public void destroy() {

}

public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse,
FilterChain filterChain) throws IOException, ServletException {
/** 1,doFilter方法的第一个参数为ServletRequest对象。此对象给过滤器提供了对进入的信息（包括
*    表单数据、cookie和HTTP请求头）的完全访问。第二个参数为ServletResponse，通常在简单的过
*    滤器中忽略此参数。最后一个参数为FilterChain，此参数用来调用servlet或JSP页。
*/

HttpServletRequest request = (HttpServletRequest)servletRequest; 
/** 如果处理HTTP请求，并且需要访问诸如getHeader或getCookies等在ServletRequest中
*    无法得到的方法，就要把此request对象构造成HttpServletRequest
*/
HttpServletResponse response = (HttpServletResponse)servletResponse;

String currentURL = request.getRequestURI(); //取得根目录所对应的绝对路径:

String targetURL = currentURL.substring(currentURL.indexOf("/", 1), 
currentURL.length()); //截取到当前文件名用于比较

HttpSession session = request.getSession(false); 
System.out.print("***********************"+session.getAttribute(Global.LOGIN_USER));
if (!"/login.action".equals(targetURL)) {
//判断当前页是否是重定向以后的登录页面页面，如果是就不做session的判断，防止出现死循环
if (session == null || session.getAttribute(Global.LOGIN_USER) == null) {
//*用户登录以后需手动添加session
System.out.println("request.getContextPath()=" + request.getContextPath()); 
response.sendRedirect(request.getContextPath() + "/login.action"); 
//如果session为空表示用户没有登录就重定向到login.jsp页面
return; 
}
}
//加入filter链继续向下执行
filterChain.doFilter(request, response); 
<filter>
    <filter-name>AuthFilter</filter-name>
    <filter-class>com.common.util.AuthFilter</filter-class>
    </filter>
    <filter-mapping>
    	<filter-name>AuthFilter</filter-name>
    	<url-pattern>*.action</url-pattern>
    </filter-mapping>
 
/**   调用FilterChain对象的doFilter方法。Filter接口的doFilter方法取一个FilterChain对象作
*     为它 的一个参数。在调用此对象的doFilter方法时，激活下一个相关的过滤器。如果没有另
*     一个过滤器与servlet或JSP页面关联，则servlet或JSP页面被激活。
*/
}

public void init(FilterConfig filterConfig) throws ServletException {

}
} 

 

<filter>
    <filter-name>AuthFilter</filter-name>
    <filter-class>com.common.util.AuthFilter</filter-class>
    </filter>
    <filter-mapping>
    	<filter-name>AuthFilter</filter-name>
    	<url-pattern>*.action</url-pattern>
    </filter-mapping>