Render方法进行html跳转报错。?报错

@JFinal 你好，想跟你请教个问题：

我是刚接触JFinal的，现在在写Demo的时候遇到一个问题，在Controller中使用render()方法进行跳转时，如果直接写render("/index,.html")，页面上会出现  500 Internal Server Error  的错误提示；后台报错如下：

严重: /hello/renderTest
java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
	at com.jfinal.core.ActionInvocation.invoke(ActionInvocation.java:61)
	at com.jfinal.core.ActionHandler.handle(ActionHandler.java:73)
	at com.jfinal.core.JFinalFilter.doFilter(JFinalFilter.java:72)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1307)
	at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:453)
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:137)
	at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:560)
	at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:231)
	at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1072)
	at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:382)
	at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:193)
	at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1006)
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:135)
	at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:116)
	at org.eclipse.jetty.server.Server.handle(Server.java:365)
	at org.eclipse.jetty.server.AbstractHttpConnection.handleRequest(AbstractHttpConnection.java:485)
	at org.eclipse.jetty.server.AbstractHttpConnection.headerComplete(AbstractHttpConnection.java:926)
	at org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.headerComplete(AbstractHttpConnection.java:988)
	at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:635)
	at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:235)
	at org.eclipse.jetty.server.AsyncHttpConnection.handle(AsyncHttpConnection.java:82)
	at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:628)
	at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:52)
	at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:608)
	at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:543)
	at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.reflect.InvocationTargetException
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at com.jfinal.core.ActionInvocation.invoke(ActionInvocation.java:55)
	... 25 more
Caused by: java.lang.NoClassDefFoundError: freemarker/template/TemplateException
	at com.jfinal.render.RenderFactory$FreeMarkerRenderFactory.getRender(RenderFactory.java:256)
	at com.jfinal.render.RenderFactory.getRender(RenderFactory.java:142)
	at com.jfinal.core.Controller.render(Controller.java:893)
	at demo.HelloController.renderTest(HelloController.java:40)
	... 30 more
Caused by: java.lang.ClassNotFoundException: freemarker.template.TemplateException
	at java.net.URLClassLoader$1.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at org.eclipse.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:430)
	at org.eclipse.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:383)
	at java.lang.ClassLoader.loadClassInternal(Unknown Source)
	... 34 more

此时我没有在配置文件中配置ViewType，代码如下：

public void configConstant(Constants me) {
		// TODO Auto-generated method stub
		me.setDevMode(true);
	}

我做了对比操作，如果在配置中将ViewType写为JSP，在Controller中使用render("/index.jsp")进行跳转，就可以实现；

同时，如果我使用renderJsp("/index.html")也可以进行跳转;

这个问题可能很小白，我查了很多资料都没有找到怎么解决，麻烦各位大神遇到过这种情况的指导一下，十分感谢。