使用GZIP动态压缩Extjs

package byd.core;

import java.io.IOException;    
import java.util.HashMap;    
import java.util.Iterator;    
import java.util.Map;    
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.HttpServletRequest;    
import javax.servlet.http.HttpServletResponse;    
  
public class GzipJsFilter implements Filter    
{    
@SuppressWarnings("unchecked")   
Map headers = new HashMap();    
  
public void destroy() { }    
  
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)    
  
throws IOException, ServletException {    
    if (req instanceof HttpServletRequest)    
      doFilter((HttpServletRequest)req, (HttpServletResponse)res, chain);    
    else    
      chain.doFilter(req, res);    
}    
  
@SuppressWarnings("unchecked")   
public void doFilter(HttpServletRequest request, HttpServletResponse response,    
  
FilterChain chain)    
    throws IOException, ServletException    
{    
    request.setCharacterEncoding("UTF-8");    
    for (Iterator it = this.headers.entrySet().iterator(); it.hasNext(); ) {    
      Map.Entry entry = (Map.Entry)it.next();    
      response.addHeader((String)entry.getKey(), (String)entry.getValue());    
    }    
    chain.doFilter(request, response);    
}    
  
@SuppressWarnings("unchecked")   
public void init(FilterConfig config) throws ServletException {    
    String headersStr = config.getInitParameter("headers");    
    String[] headers = headersStr.split(",");    
    for (int i = 0; i < headers.length; ++i) {    
      String[] temp = headers[i].split("=");    
      this.headers.put(temp[0].trim(), temp[1].trim());    
    }    
}    
}  

<filter>    
      <filter-name>GzipJsFilter</filter-name>    
      <filter-class>com.byd.core.GzipJsFilter</filter-class>    
      <init-param>    
          <param-name>headers</param-name>    
          <param-value>Content-Encoding=gzip</param-value>    
      </init-param>    
</filter>    
<filter-mapping>    
   <filter-name>GzipJsFilter</filter-name>    
   <url-pattern>*.gzjs</url-pattern>    
</filter-mapping>