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1。如果要映射过滤应用程序中所有资源:
<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-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-mapping>
<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 class
ResponseHeaderFilter implements
Filter {
FilterConfig
fc;
public void
doFilter(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 void
init(FilterConfig filterConfig) {
this.fc = filterConfig;
}
public void
destroy() {
this.fc = null;
}
}
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原文地址:http://www.cnblogs.com/kabi/p/5182872.html