爱华网<filter>
<filter-name>loggerfilter</filter-name>
<filter-class>myfilter.LoggerFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>loggerfilter</filter-name>
<url-pattern>/*</url-pattern>//访问当前主机，当前应用程序根下的所有文件包括多级子目录下的所有文件，注意这里*前有“/”
</filter-mapping>
2.过滤指定的类型文件资源
<filter>
<filter-name>loggerfilter</filter-name>
<filter-class>myfilter.LoggerFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>loggerfilter</filter-name>
<url-pattern>*.html</url-pattern>//访问当前主机，当前应用程序根目录下的所有html文件，注意：*.html前没有“/”,否则错误
</filter-mapping>
其中*.html要过滤jsp那么就改*.html为*.jsp,但是注意没有“/”斜杠
如果要同时过滤多种类型资源：
方法一：url-pattern分开写
<filter>
<filter-name>loggerfilter</filter-name>
<filter-class>myfilter.LoggerFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>loggerfilter</filter-name>
<url-pattern>*.html</url-pattern>
</filter-mapping>
<filter-name>loggerfilter</filter-name>
<url-pattern>*.jsp</url-pattern>//访问当前主机，当前应用程序根目录以所有及子目录下的所有jsp文件
</filter-mapping>
方法二、将url-pattern 合并
<filter>
<filter-name>loggerfilter</filter-name>
<filter-class>myfilter.LoggerFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>loggerfilter</filter-name>
<url-pattern>*.html;*.jsp</url-pattern>
</filter-mapping>//*.html;*.jsp两类型之间用分号“；”间隔
3.过滤指定的目录下的所有文件
<filter>
<filter-name>loggerfilter</filter-name>
<filter-class>myfilter.LoggerFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>loggerfilter</filter-name>
<url-pattern>/folder_name/*</url-pattern>//访问当前主机，当前应用程序根目录下的folder_name子目录（可以是多级子目录）下所有文件
</filter-mapping>
4.过滤指定的servlet
<filter>
<filter-name>loggerfilter</filter-name>
<filter-class>myfilter.LoggerFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>loggerfilter</filter-name>
<servlet-name>loggerservlet</servlet-name></filter-mapping>
<servlet>
<servlet-name>loggerservlet</servlet-name>
<servlet-class>myfilter.LoggerServlet</servlet-class>
</servlet>
5.过滤指定文件（即单一文件）
<filter>
<filter-name>loggerfilter</filter-name>
<filter-class>myfilter.LoggerFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>loggerfilter</filter-name>
<url-pattern>/simplefilter.html</url-pattern>
</filter-mapping>
6、过滤指定目录下的指定类型的所有文件
这种情况下，在web.xml中无法一次性配置完成，需要结合filter的实现类
首先，在web.xml中配置过滤指定目录下的所有文件（如上3）
<filter>
<filter-name>loggerfilter</filter-name>
<filter-class>myfilter.LoggerFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>loggerfilter</filter-name>
<url-pattern>/dir_name/*</url-pattern>
</filter-mapping>
然后，在filter的实现类中的doFilter方法中获取请求的uri或者url，判断uri或者url中是否包含指定文件类型的字符串，决定是否过滤
//获得用户请求的uri
String uri =request.getRequestURI();
if(uri.contains(".jsp")||uri.contains(".html"))
{
System.out.println("开始过滤"+url);
}
7、过滤指定目录下指定类型的单一文件
<filter>
<filter-name>loggerfilter</filter-name>
<filter-class>myfilter.LoggerFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>loggerfilter</filter-name>
<url-pattern>/dir_name/index.jsp</url-pattern>
</filter-mapping>
以上都要注意是否有斜杠“/”
###############使用filter缓存js、css、图片等文件###############
在web.xml中配置如下信息
<!--不缓存文件 -->
<filter>
<filter-name>NoCache</filter-name>
<filter-class>com.sys.common.Filters.ResponseHeaderFilter
</filter-class>
<init-param>
<param-name>Cache-Control</param-name>
<param-value>no-cache,must-revalidate</param-value>
</init-param>
</filter>
<!--缓存文件一周 -->
<filter>
<filter-name>CacheForWeek</filter-name>
<filter-class>com..sys.common.Filters.ResponseHeaderFilter
</filter-class>
<init-param>
<param-name>Cache-Control</param-name>
<param-value>max-age=604800,public</param-value>
</init-param>
</filter>
<filter-name>CacheForWeek</filter-name>
<url-pattern>/images/*</url-pattern>
</filter-mapping>
<filter-mapping>
<filter-name>CacheForWeek</filter-name>
<url-pattern>*.js</url-pattern>
</filter-mapping>
<filter-mapping>
<filter-name>CacheForWeek</filter-name>
<url- pattern>*.css</url-pattern>
</filter-mapping>
自定义的filter如下：
public classResponseHeaderFilter implementsFilter {
FilterConfigfc;
public voiddoFilter(ServletRequest req, ServletResponse res,
FilterChain chain) throws IOException, ServletException {
HttpServletResponse response = (HttpServletResponse) res;
// set the provided HTTP response parameters
for (Enumeration e = fc.getInitParameterNames();e.hasMoreElements();) {
String headerName = (String) e.nextElement();
response.addHeader(headerName,fc.getInitParameter(headerName));
}
// pass the request/response on
chain.doFilter(req, response);
}
public voidinit(FilterConfig filterConfig) {
this.fc = filterConfig;
}
public voiddestroy() {
this.fc = null;
}
}
