编写过滤器
这里主要提供了js,css缓存
如果想要的话,自己可以直接添加图片的映射
package com.foo.filter;
import org.apache.log4j.Logger;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.Enumeration;
public class ReplyHeaderFilter implements Filter
{
static Logger log = Logger.getLogger(ReplyHeaderFilter.class);
private String[][] replyHeaders = {{}};
public void init(FilterConfig config)
{
Enumeration names = config.getInitParameterNames();
ArrayList tmp = new ArrayList();
while (names.hasMoreElements())
{
String name = (String)names.nextElement();
String value = config.getInitParameter(name);
log.debug("Adding header name: " + name + "='" + value + "'");
String[] pair = {name, value};
tmp.add(pair);
}
replyHeaders = new String[tmp.size()][2];
tmp.toArray(replyHeaders);
}
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain)
throws IOException, ServletException
{
// Apply the headers
HttpServletResponse httpResponse = (HttpServletResponse)response;
for (int n = 0; n < replyHeaders.length; n++)
{
String name = replyHeaders[n][0];
String value = replyHeaders[n][1];
httpResponse.setHeader(name, value);
}
long relExpiresInMillis = System.currentTimeMillis() + (1000 * 259200);
httpResponse.setHeader("Expires", getGMTTimeString(relExpiresInMillis));
chain.doFilter(request, response);
}
public static String getGMTTimeString(long milliSeconds)
{
SimpleDateFormat sdf = new SimpleDateFormat("E, d MMM yyyy HH:mm:ss 'GMT'");
return sdf.format(new Date(milliSeconds));
}
public void destroy()
{
}
}
<filter>
<description>Adds cacheing to content output files.</description>
<filter-name>CacheControlFilter</filter-name>
<filter-class>com.foo.filter.ReplyHeaderFilter</filter-class>
<init-param>
<param-name>Cache-Control</param-name>
<param-value>public,max-age=86400</param-value>
</init-param>
<init-param>
<param-name>Pragma</param-name>
<param-value>public</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>CacheControlFilter</filter-name>
<url-pattern>*.js</url-pattern>
</filter-mapping>
<filter-mapping>
<filter-name>CacheControlFilter</filter-name>
<url-pattern>*.css</url-pattern>
</filter-mapping>