## filterConfig 1. 獲取filter名稱. 2. 獲取filter的初始化參數. 3. 獲取filter所有初始化名稱. 4. 獲取上下文. ## 實例 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"); //獲取filter名稱 System.out.println(filterConfig.getFilterName()); //獲取filter初始化參數 System.out.println(filterConfig.getInitParameter("name")); //獲取所有filter初始化參數 Enumeration<String> initParameterNames = filterConfig.getInitParameterNames(); while (initParameterNames.hasMoreElements()) { String s = initParameterNames.nextElement(); System.out.println(s + ":" + filterConfig.getInitParameter(s)); } //獲取filter上下文對象 System.out.println(filterConfig.getServletContext()); chain.doFilter(req, resp); System.out.println("showFilter response"); ~~~ 結果 ``` showFilter request ShowFilter jack name:jack db:mysql org.apache.catalina.core.ApplicationContextFacade@597bdf9f 1 showFilter response ```