開啓ssi步驟如下：
1、apache-tomcat-7.0.72\conf目錄下context.xml 中<Context>修改爲<Context privileged="true">
2、apache-tomcat-7.0.72\conf目錄下web.xml 中去掉下面代碼的註釋
a、
<servlet>
<servlet-name>ssi</servlet-name>
<servlet-class>
org.apache.catalina.ssi.SSIServlet
</servlet-class>
<init-param>
<param-name>buffered</param-name>
<param-value>1</param-value>
</init-param>
<init-param>
<param-name>inputEncoding</param-name>
<param-value>UTF-8</param-value>
</init-param>
<init-param>
<param-name>outputEncoding</param-name>
<param-value>UTF-8</param-value>
</init-param>
<init-param>
<param-name>debug</param-name>
<param-value>0</param-value>
</init-param>
<init-param>
<param-name>expires</param-name>
<param-value>666</param-value>
</init-param>
<init-param>
<param-name>isVirtualWebappRelative</param-name>
<param-value>0</param-value>
</init-param>
<load-on-startup>4</load-on-startup>
</servlet>
b、
<servlet-mapping>
<servlet-name>ssi</servlet-name>
<url-pattern>*.html</url-pattern>
</servlet-mapping>
並加上<url-pattern>*.shtml</url-pattern>
之後變成
<servlet-mapping>
<servlet-name>ssi</servlet-name>
<url-pattern>*.html</url-pattern>
<url-pattern>*.shtml</url-pattern>
</servlet-mapping>
3、這一步很重要！！！在apache-tomcat-7.0.72\conf目錄下web.xml 中搜索<extension>shtml</extension>
將代碼
<mime-mapping>
<extension>shtml</extension>
<mime-type>text/x-server-parsed-html</mime-type>
</mime-mapping>
改成
<mime-mapping>
<extension>html</extension>
<mime-type>text/html</mime-type>
</mime-mapping>
<mime-mapping>
<extension>shtml</extension>
<mime-type>text/html</mime-type>
</mime-mapping>
對，你沒看錯，將一份變成兩份了，並且mime-type變成了text/html了
然後重啓tomcat就可以在html文件中使用include指令了
指令格式： <!--#include virtual="../include/ad.html" -->
注意 ： <!--#include 這些字符中間是沒有空格的
另外就是WEB-INF下面的xml中不要又這樣的配置：
<jsp-config>
<jsp-property-group>
<url-pattern>*.html</url-pattern>
<trim-directive-whitespaces>true</trim-directive-whitespaces>
</jsp-property-group>
</jsp-config>
不然的話ssi是不起作用的，就是因爲這個原因。。。。搞了好幾天。。。。