package gboat2.base.plugin.servlet.filter;
   
   import java.io.IOException;
   import java.net.URL;
   import java.net.URLConnection;
   
   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;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  
  /**
   * CSS 文件过滤器，解决某些主题下有部分 CSS 文件不存在的问题。<br>
   * 在 web.xml 中添加如下配置启用该过滤器：
   * <pre><code>
   * &lt;!-- css过滤器 --&gt;
   * &lt;filter&gt;
   *     &lt;filter-name&gt;gboat2CssFilter&lt;/filter-name&gt;
   *     &lt;filter-class&gt;gboat2.base.plugin.servlet.filter.GboatCSSFilter&lt;/filter-class&gt;
   * &lt;/filter&gt;
   * &lt;filter-mapping&gt;
   *     &lt;filter-name&gt;gboat2CssFilter&lt;/filter-name&gt;
   *     &lt;url-pattern&gt;*.css&lt;/url-pattern&gt;
   * &lt;/filter-mapping&gt;
   * </code></pre>
   * @date 2012-4-17
   * @author zhangxj-a
   * @author <a href="mailto:[email protected]">何明旺</a>
   * @since 1.0
   */
  public class GboatCSSFilter implements Filter {
  	
  	private static Logger logger = LoggerFactory.getLogger(GboatCSSFilter.class);
  	
  	@Override
  	public void init(FilterConfig arg0) throws ServletException {
  		
  	}
  	
  	@Override
  	public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
  		HttpServletRequest request = (HttpServletRequest) req;
  		HttpServletResponse response = (HttpServletResponse) res;
  		
  		String requestURL = request.getRequestURL().toString();
  		String queryString = request.getQueryString();
  		if (null != queryString) {
  			requestURL += ("?" + queryString);
  		}
  		
  		if (requestURL.contains("$")) {
  			logger.info("deal css file : " + requestURL);
  			//替换uri中的'$'
  			requestURL = requestURL.replace("$", "");
  			// http://192.168.69.68:8080/G2/static/gboat2.base.logginges/gray/css/logging_style.css
  			
  			URLConnection urlCon = null;
  			
  			try {
  				urlCon = new URL(requestURL).openConnection();
  				urlCon.setConnectTimeout(0);
  				urlCon.setReadTimeout(0);
  				 // 文件存在返回‘HTTP/1.1 200 OK’；文件不存在返回 ‘HTTP/1.1 404 Not Found’
  				String message = urlCon.getHeaderField(0);
  				//判断文件是否存在
  				if (message.equals("HTTP/1.1 200 OK")) {
  					response.sendRedirect(requestURL);
  				} else {
  					String newURL = requestURL.replace(requestURL.substring(requestURL.indexOf("/themes/") + 8, requestURL.indexOf("/css/")), "default");
  					response.sendRedirect(newURL);
  				}
  			} catch (Exception e) {
  				logger.error("CSS 过滤器发生错误。", e);
  			}
  		} else {
  			chain.doFilter(request, response);
  		}
  	}
  	
  	@Override
  	public void destroy() {
  	}
  	
  }