servlet拦截器代码

最新推荐文章于 2023-04-11 11:12:17 发布

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本文介绍如何通过实现Servlet.Filter接口创建自定义过滤器。过滤器会在请求到达目标资源之前进行检查，例如验证用户是否已登录。如果未登录则重定向到登录页面，已登录则继续处理请求。

<span style="font-size:14px;">1-实现Servlet.Filter接口
public class AdminLoginFilter implements Filter


新建一个实现filter接口的类,实现dofilter方法，在dofilter方法里面写一个判读，比如如果用户名密码为空，则返回到登录页面
public class TestFilter  implements Filter  { 
public void doFilter(ServletRequest srt, ServletResponse sre,
   FilterChain filterChain) throws IOException, ServletException {
 
  HttpServletRequest request = (HttpServletRequest)srt;
  HttpServletResponse response = (HttpServletResponse)sre;
 
  String name= (String)request.getSession().getAttribute("name");
 
  if( name== null || name.trim().length() < 1) {
 
  
   response.sendRedirect( "/denglu.jsp" );
  }else {
   filterChain.doFilter(request, response);
  }
}


web.xml配置过滤器
  <filter>
   <filter-name>TestFilter  </filter-name>
   <filter-class>/test/TestFilter  </filter-class>
  </filter>

配置多个映射，哪些请求执行过滤器
  <filter-mapping>
   <filter-name>TestFilter  </filter-name>
   <url-pattern>/web-inf/test/*</url-pattern>
  </filter-mapping>
  <filter-mapping>
   <filter-name>TestFilter  </filter-name>
   <url-pattern>/login.do</url-pattern>
  </filter-mapping>

  <filter-mapping>
   <filter-name>TestFilter  </filter-name>
   <url-pattern>/loginin.do</url-pattern>
  </filter-mapping></span>