用 Servlet Filter 缓存页面图片、js教本等静态信息(源码)
摘自久久学院
/*
* <p>Company: 凌科软件 www.elingke.com </p>
* @author liubaojun
* @version 1.0
* 来源于 elinkBSP 部分源代码
*/
package com.elink.control;
import java.io.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
import com.elink.util.*;
/**
* @author liubj
*/
public class BusiCacheFilter implements Filter
{
private FilterConfig config = null;
private HashMap expiresMap = new HashMap();
public void init(FilterConfig filterConfig)
{
this.config = filterConfig;
expiresMap.clear();
Enumeration names = config.getInitParameterNames();
while( names.hasMoreElements() )
{
try
{
String name = (String)names.nextElement();
String value = config.getInitParameter( name );
Integer expire = Integer.valueOf( value );
expiresMap.put( name, expire );
}
catch( Exception ex)
{
}
}
}
public void doFilter( ServletRequest request, ServletResponse response, FilterChain chain)
throws IOException, ServletException
{
HttpServletRequest req = (HttpServletRequest) request;
HttpServletResponse res = (HttpServletResponse) response;
String uri = req.getRequestURI();
String ext = null;
int dot = uri.lastIndexOf(".");
if( dot != -1 )
{
ext = uri.substring( dot+1 );
}
setResponseHeader( res, uri, ext );
chain.doFilter(request, response);
}
public void destroy()
{
}
protected FilterConfig getFilterConfig()
{
return (config);
}
private void setResponseHeader( HttpServletResponse response, String uri, String ext )
{
if( ext!= null && ext.length() > 0 )
{
Integer expires = (Integer)expiresMap.get(ext);
if( expires != null )
{
LogUtil.logDebug( uri + ".Expires: "+ expires.intValue());
if( expires.intValue() > 0 )
{
response.setHeader("Cache-Control","max-age="+expires.intValue()); //HTTP 1.1
}
else
{
response.setHeader("Cache-Control","no-cache");
response.setHeader("Pragma","no-cache"); //HTTP 1.0
response.setDateHeader ("Expires", 0 );
}
}
}
}
}
web.xml
<filter>
<filter-name>busicachefilter</filter-name>
<filter-class>com.elink.control.BusiCacheFilter</filter-class>
<init-param>
<param-name>js</param-name>
<param-value>3600</param-value>
</init-param>
<init-param>
<param-name>gif</param-name>
<param-value>3600</param-value>
</init-param>
<init-param>
<param-name>jpg</param-name>
<param-value>3600</param-value>
</init-param>
<init-param>
<param-name>css</param-name>
<param-value>3600</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>busicachefilter</filter-name>
<url-pattern>*.js</url-pattern>
</filter-mapping>
<filter-mapping>
<filter-name>busicachefilter</filter-name>
<url-pattern>*.gif</url-pattern>
</filter-mapping>
<filter-mapping>
<filter-name>busicachefilter</filter-name>
<url-pattern>*.jpg</url-pattern>
</filter-mapping>
<filter-mapping>
<filter-name>busicachefilter</filter-name>
<url-pattern>*.css</url-pattern>
</filter-mapping>