java.lang.ClassNotFoundException：org.apache.commons.lang.ex

我试图从数据库中检索数据.当我运行程序它显示错误 java.lang.ClassNotFoundException：org.apache.commons.lang.exception.NestableRuntimeException我有json-lib jar文件在我的WEB-INF – > lib目录,我不知道为什么它显示 JSONArray的这个错误.

我的代码是：

StringBuilder sb=new StringBuilder(1024);
        sb.append("select * from ").append(uname.trim()).append("vcomments").append(" where itemid=").append(itemId).append(" and albumid=").append(albumId);
        sql=sb.toString();
        stmt = conn.prepareStatement(sql);
        ResultSet rs = stmt.executeQuery();
        //ArrayList<String> CommArray=new ArrayList();
        JSONArray arrayObj=new JSONArray();                //#100


         while(rs.next()){
            Commenter comment = new Commenter();
            comment.setUname(rs.getString("uname").trim());
            comment.setComment(rs.getString("comments").trim());
            arrayObj.add(comment.toString());

            }    
         commentObj=gson.toJsonTree(arrayObj);
         myObj.add("commentInfo",commentObj);
         out.println(myObj.toString());
         rs.close();                                                              
         stmt.close();                                                            
         stmt = null;                                                             


         conn.close();                                                            
         conn = null;                                                  

     }

控制台的输出是：

SEVERE: Servlet.service() for servlet [VComment] in context with path [/skypark] 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:1714)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1559)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at org.apache.catalina.loader.WebappClassLoader.findClassInternal(WebappClassLoader.java:2904)
at org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:1173)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1681)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1559)
at skypark.VComment.doGet(VComment.java:100)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:931)
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:1004)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

请有人告诉我如何解决这个问题……谢谢….