<filter>
<filter-name>loggerfilter</filter-name>
<filter-class>myfilter.LoggerFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>loggerfilter</filter-name>
<url-pattern>/*</url-pattern>//訪問當(dāng)前主機(jī)，當(dāng)前應(yīng)用程序根下的所有文件包括多級(jí)子目錄下的所有文件，注意這里*前有“/”
</filter-mapping>

2.過濾指定的類型文件資源

<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>//訪問當(dāng)前主機(jī)，當(dāng)前應(yīng)用程序根目錄下的所有html文件，注意：*.html前沒有“/”,否則錯(cuò)誤

</filter-mapping>

其中*.html要過濾jsp那么就改*.html為*.jsp,但是注意沒有“/”斜杠

如果要同時(shí)過濾多種類型資源：

方法一：url-pattern分開寫

<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>

方法二、將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兩類型之間用分號(hào)“；”間隔

3.過濾指定的目錄下的所有文件

<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>//訪問當(dāng)前主機(jī)，當(dāng)前應(yīng)用程序根目錄下的folder_name子目錄（可以是多級(jí)子目錄）下所有文件

</filter-mapping>

4.過濾指定的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.過濾指定文件（即單一文件）

<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、過濾指定目錄下的指定類型的所有文件

這種情況下，在web.xml中無(wú)法一次性配置完成，需要結(jié)合filter的實(shí)現(xiàn)類

首先，在web.xml中配置過濾指定目錄下的所有文件（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的實(shí)現(xiàn)類中的doFilter方法中獲取請(qǐng)求的uri或者url，判斷uri或者url中是否包含指定文件類型的字符串，決定是否過濾

//獲得用戶請(qǐng)求的uri
String uri =request.getRequestURI();

if(uri.contains(".jsp")||uri.contains(".html"))
{
System.out.println("開始過濾"+url);
}

7、過濾指定目錄下指定類型的單一文件

<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緩存js、css、圖片等文件###############

在web.xml中配置如下信息

<!--不緩存文件 -->

<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>

<!--緩存文件一周 -->

<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>

自定義的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;
}

}

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