## filterConfig 1. 获取filter名称. 2. 获取filter的初始化参数. 3. 获取filter所有初始化名称. 4. 获取上下文. ## 实例 web.xml ~~~ <filter> <filter-name>ShowFilter</filter-name> <filter-class>com.like.ShowFilter</filter-class> <init-param> <param-name>name</param-name> <param-value>jack</param-value> </init-param> <init-param> <param-name>db</param-name> <param-value>mysql</param-value> </init-param> </filter> <filter-mapping> <filter-name>ShowFilter</filter-name> <url-pattern>/show</url-pattern> </filter-mapping> ~~~ filter ~~~ System.out.println("showFilter request"); //获取filter名称 System.out.println(filterConfig.getFilterName()); //获取filter初始化参数 System.out.println(filterConfig.getInitParameter("name")); //获取所有filter初始化参数 Enumeration<String> initParameterNames = filterConfig.getInitParameterNames(); while (initParameterNames.hasMoreElements()) { String s = initParameterNames.nextElement(); System.out.println(s + ":" + filterConfig.getInitParameter(s)); } //获取filter上下文对象 System.out.println(filterConfig.getServletContext()); chain.doFilter(req, resp); System.out.println("showFilter response"); ~~~ 结果 ``` showFilter request ShowFilter jack name:jack db:mysql org.apache.catalina.core.ApplicationContextFacade@597bdf9f 1 showFilter response ```