Http客户端程序错误

Question

我在MAC上使用netbeans 7.4。在编译以下程序时，我遇到了一些异常。

我的代码：

import java.io.*;

import org.apache.commons.httpclient.*;


import org.apache.commons.httpclient.methods.*;

import org.apache.commons.httpclient.params.HttpMethodParams;


public class HttpClientSample 
{

      private static String url = "http://www.apache.org/"; 
      public static void main(String[] args) 
      {
       // Constructor for HttpClient  
          HttpClient client = new HttpClient();

       //Creeating a method

         GetMethod method = new GetMethod(url);

      method.getParams().setParameter(HttpMethodParams.RETRY_HANDLER, new DefaultHttpMethodRetryHandler(3,false));

      try
      {
          //Execute the method 
          int statusCode = client.executeMethod(method);
        //  System.out.println("vikas is my name ");

          if(statusCode != HttpStatus.SC_OK)
          {
              System.err.println("Method failes : " + method.getStatusLine());

          }

         //Read the response body
          byte[] responsebody = method.getResponseBody();

          //Print the response

          System.out.println(new String(responsebody));

      } 
      catch (HttpException e) 
      {
            System.out.println("fatal protocol violation: " + e.getMessage());
            e.printStackTrace();
      }
      catch (IOException e )
      {
            System.out.println("fatal transport error : " + e.getMessage());
            e.printStackTrace();
      }
      finally 
      {
            // release the connection

          method.releaseConnection();
      }
    }
}

运行程序后，我收到以下异常：

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/logging/LogFactory
    at org.apache.commons.httpclient.HttpClient.<clinit>(HttpClient.java:66)
    at JavaApplication1.main(JavaApplication1.java:13)
Caused by: java.lang.ClassNotFoundException: org.apache.commons.logging.LogFactory
    at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:358)

任何人都可以帮助我的代码中的问题.. 谢谢你提前..