VelocityServlet: Error processing the template

java.lang.NullPointerException
	at com.ys.cache.StaticFileCache.loadFile(StaticFileCache.java:173)
	at com.ys.cache.StaticFileCache.getFile(StaticFileCache.java:119)
	at com.ys.dictzone.Index.handleRequest(Index.java:126)
	at com.ys.utils.VelocityServlet.doRequest(VelocityServlet.java:321)
	at com.ys.utils.VelocityServlet.doGet(VelocityServlet.java:281)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
	at com.ys.cache.GzipCachingFilter.buildPage(GzipCachingFilter.java:216)
	at com.ys.cache.GzipCachingFilter.buildPageInfo(GzipCachingFilter.java:181)
	at com.ys.cache.GzipCachingFilter.doFilter(GzipCachingFilter.java:146)
	at com.ys.cache.GzipCachingFilter.doFilter(GzipCachingFilter.java:123)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:224)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
	at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
	at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:987)
	at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:579)
	at org.apache.tomcat.util.net.AprEndpoint$SocketWithOptionsProcessor.run(AprEndpoint.java:1763)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
	at java.lang.Thread.run(Thread.java:722)