java中如何用过滤器来拦截用户不允许访问的网页（通过地址栏来进行拦截）

过滤器用来拦截用户不允许访问的网页（通过地址栏来进行拦截）

例如：等用户在地址栏输入访问地址后跳转时进行拦截，只允许访问集合中存在的这些网页，在web.xml中先进行如下配置

FilterSerlvet

com.zt.filter.FilterSerlvet

code

utf-8

FilterSerlvet

/*

过滤器的写法

public class FilterSerlvet implements Filter {

private List paths =new ArrayList();//实例化一个装路径的集合

public void doFilter(ServletRequest arg0, ServletResponse arg1,
FilterChain chain ) throws IOException, ServletException {
HttpServletRequest request =(HttpServletRequest) arg0;
HttpServletResponse response =(HttpServletResponse) arg1;
String contextPath =request.getContextPath();
String path =request.getRequestURL().toString();
System.out.println(contextPath);//  20170512filter2
System.out.println(path);//  http://localhost:8080/20170512filter2/user1/list.jsp int num =path.indexOf(contextPath)+contextPath.length();
String relpath =path.substring(num+1);
if (paths.contains(relpath)) {
chain.doFilter(request, response);
}else {
response.sendRedirect("../index.jsp");
}

}
public void init(FilterConfig arg0) throws ServletException {
// TODO Auto-generated method stub

//将允许访问的网页路径放入集合中，实际开发中应该是从数据库中取允许访问的路径
paths.add("user1/list.jsp");
paths.add("user2/list.jsp");
paths.add("user3/list.jsp");
paths.add("index.jsp");
}
public void destroy() {
// TODO Auto-generated method stub

}

}