嚴重: Servlet.service() for servlet [SearchServlet] in context with path [/ajax_autocomplete] threw exception [Servlet execution threw an exception] with root cause

java.lang.ClassNotFoundException: org.apache.commons.lang.exception.NestableRuntimeException

at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1711)

at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1556)

at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)

at java.lang.ClassLoader.defineClass1(Native Method)

at java.lang.ClassLoader.defineClass(ClassLoader.java:621)

.......

package?imooc.ajaxautocomplete.search;

import?java.io.IOException;
import?java.util.ArrayList;
import?java.util.List;

import?javax.servlet.ServletException;
import?javax.servlet.http.HttpServlet;
import?javax.servlet.http.HttpServletRequest;
import?javax.servlet.http.HttpServletResponse;

import?net.sf.json.JSONArray;

public?class?SearchServlet?extends?HttpServlet?{

	static?List<String>?datas=new?ArrayList<String>();
	static{
		datas.add("ajax");
		datas.add("ajax操作");
		datas.add("ajax基礎教程");
		datas.add("boolean");
		datas.add("CoCo");
	}
	
	@Override
	protected?void?doGet(HttpServletRequest?request,?HttpServletResponse?response)
			throws?ServletException,?IOException?{
		request.setCharacterEncoding("utf-8");
		response.setCharacterEncoding("utf-8");
		
		//首先獲得客戶端發送來的數據keyword
		String?keyword=request.getParameter("keyword");
		//獲得關鍵字之后進行處理，得到關聯數據
		List<String>?listData=getData(keyword);
		//返回json格式
		response.getWriter().write(JSONArray.fromObject(listData).toString());
	}
	
	//獲得關聯數據的方法
	public?List<String>?getData(String?keyword){
		List<String>?list=new?ArrayList<String>();
		for(String?data:datas){
			if(data.contains(keyword)){
				list.add(data);
			}
		}
		return?list;
	}

}

------------------------------------

<?xml?version="1.0"?encoding="UTF-8"?>
<web-app?version="2.5"?
	xmlns="http://java.sun.com/xml/ns/javaee"?
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"?
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee?
	http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
??<display-name></display-name>
??<servlet>
????<description>This?is?the?description?of?my?J2EE?component</description>
????<display-name>This?is?the?display?name?of?my?J2EE?component</display-name>
????<servlet-name>SearchServlet</servlet-name>
????<servlet-class>imooc.ajaxautocomplete.search.SearchServlet</servlet-class>
??</servlet>

??<servlet-mapping>
????<servlet-name>SearchServlet</servlet-name>
????<url-pattern>/search</url-pattern>
??</servlet-mapping>	
??<welcome-file-list>
????<welcome-file>index.jsp</welcome-file>
??</welcome-file-list>

</web-app>