如何在只使用tomcat的情况下,自动缓存js和css或者image等文件

该方法分为以下3个步骤
第一步:写一个filter,可以根据路径的正则来判断该路径的请求是否需要设置max-age:
Java代码
/**
*
* @author ahuaxuan
* @date 2008-12-4
* @version $id$
*/  
public class CacheFilter implements Filter{   
  
    private static transient Log logger = LogFactory.getLog(CacheFilter.class);   
       
    private Integer cacheTime = 3600 * 24;   
    private List<Pattern> patternList = new ArrayList<Pattern>();   
       
    private static ResourceBundle rb = ResourceBundle.getBundle("cache-pattern");   
    public void destroy() {   
           
     }   
  
    public void doFilter(ServletRequest rq, ServletResponse rqs,   
             FilterChain fc) throws IOException, ServletException {   
           
         fc.doFilter(rq, rqs);   
        if (rq instanceof HttpServletRequest && rqs instanceof HttpServletResponse) {   
             HttpServletRequest request = (HttpServletRequest) rq;   
             HttpServletResponse response = (HttpServletResponse) rqs;   
               
            if (matchPattern(request.getRequestURI())) {   
                 response.setHeader("Cache-Control", "max-age=" + cacheTime);   
                if (logger.isDebugEnabled()) {   
                     StringBuilder sb = new StringBuilder();   
                     sb.append(" set cache control for uri = ").append
(request.getRequestURI());   
                     sb.append(" and the cache time is ").append(cacheTime).append("

second");   
                     logger.debug(sb.toString());   
                 }   
             }   
           
         } else {   
            if (logger.isWarnEnabled()) {   
                 logger.warn("---- the request instance is not instanceof

HttpServletRequest ---");   
                 logger.warn("---- the response instance is not instanceof

HttpServletResponse ---");   
             }   
         }   
           
     }   
  
    public void init(FilterConfig arg0) throws ServletException {   
         Enumeration<String> keys = rb.getKeys();   
        while (keys.hasMoreElements()) {   
             String p = keys.nextElement();   
             String value = rb.getString(p);   
             patternList.add(Pattern.compile(value, Pattern.CASE_INSENSITIVE));   
               
            if (logger.isInfoEnabled()) {   
                 logger.info(">>>>>>>>>>> init the cache pattern " + value);   
             }   
         }   
           
        if (arg0 != null) {   
             String ct = arg0.getInitParameter("cache-time");   
            if (!"".equals(ct) && null != ct) {   
                 cacheTime = new Integer(ct);   
                if (logger.isInfoEnabled()) {   
                     logger.info(">>>>>>>>>> the cache time is " + cacheTime);   
                 }   
             }   
         }   
     }   
       
    private boolean matchPattern(String url) {   
        for (Pattern pattern : patternList) {   
            if (pattern.matcher(url).matches()) {   
                return true;   
             }   
         }   
           
        return false;   
     }   
  
    public static void main(String [] args) throws ServletException {   
         CacheFilter cf = new CacheFilter();   
         cf.init(null);   
         System.out.println(cf.matchPattern("/css/prototype.CSS"));   
     }   
} 

/**
*
* @author ahuaxuan
* @date 2008-12-4
* @version $id$
*/
public class CacheFilter implements Filter{

private static transient Log logger = LogFactory.getLog(CacheFilter.class);

private Integer cacheTime = 3600 * 24;
private List<Pattern> patternList = new ArrayList<Pattern>();

private static ResourceBundle rb = ResourceBundle.getBundle("cache-pattern");
public void destroy() {

}

public void doFilter(ServletRequest rq, ServletResponse rqs,
   FilterChain fc) throws IOException, ServletException {

fc.doFilter(rq, rqs);
if (rq instanceof HttpServletRequest && rqs instanceof HttpServletResponse) {
   HttpServletRequest request = (HttpServletRequest) rq;
   HttpServletResponse response = (HttpServletResponse) rqs;
  
   if (matchPattern(request.getRequestURI())) {
    response.setHeader("Cache-Control", "max-age=" + cacheTime);
    if (logger.isDebugEnabled()) {
     StringBuilder sb = new StringBuilder();
     sb.append(" set cache control for uri = ").append(request.getRequestURI());
     sb.append(" and the cache time is ").append(cacheTime).append(" second");
     logger.debug(sb.toString());
    }
   }

} else {
   if (logger.isWarnEnabled()) {
    logger.warn("---- the request instance is not instanceof HttpServletRequest ---");
    logger.warn("---- the response instance is not instanceof HttpServletResponse ---");
   }
}

}

public void init(FilterConfig arg0) throws ServletException {
Enumeration<String> keys = rb.getKeys();
while (keys.hasMoreElements()) {
   String p = keys.nextElement();
   String value = rb.getString(p);
   patternList.add(Pattern.compile(value, Pattern.CASE_INSENSITIVE));
  
   if (logger.isInfoEnabled()) {
    logger.info(">>>>>>>>>>> init the cache pattern " + value);
   }
}

if (arg0 != null) {
   String ct = arg0.getInitParameter("cache-time");
   if (!"".equals(ct) && null != ct) {
    cacheTime = new Integer(ct);
    if (logger.isInfoEnabled()) {
     logger.info(">>>>>>>>>> the cache time is " + cacheTime);
    }
   }
}
}

private boolean matchPattern(String url) {
for (Pattern pattern : patternList) {
   if (pattern.matcher(url).matches()) {
    return true;
   }
}

return false;
}

public static void main(String [] args) throws ServletException {
CacheFilter cf = new CacheFilter();
cf.init(null);
System.out.println(cf.matchPattern("/css/prototype.CSS"));
}
}
第二步:在classpath路径下创建一个cache-pattern.properties文件,内容如下:
Java代码
1 = .*ext-all.js   
2 = .*prototype.js   
3 = .*/css/.*\\.css 

1 = .*ext-all.js
2 = .*prototype.js
3 = .*/css/.*\\.css

在这个配置文件中,您可以根据js和css的路径来配置哪些目录,或者哪些文件需要设置max-age.

第三步:
在web.xml添加如下内容:
Java代码
<filter>   
          <filter-name>cache-filter</filter-name>   
          <filter-class>com.tudou.tudouadsales.component.web.filter.CacheFilter</filter-

class>   
          <init-param>   
             <param-name>cache-time</param-name>   
             <param-value>86000</param-value>   
         </init-param>   
     </filter>   
  
<filter-mapping>   
         <filter-name>cache-filter</filter-name>   
         <url-pattern>*.js</url-pattern>   
     </filter-mapping>   
       
     <filter-mapping>   
         <filter-name>cache-filter</filter-name>   
         <url-pattern>*.css</url-pattern>   
</filter-mapping> 


注：本文转自http://d-tune.iteye.com/blog/638715