求助：java中httpclient包怎么使用啊？？尝试的get方法出错，怎么解决？
主要代码：HttpClient client = new HttpClient();
GetMethod get = new GetMethod("http://www.163.com/");//第17行！
client.executeMethod(get);
System.out.println(get.getResponseBodyAsString());
get.releaseConnection();
出错信息：
Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/codec/DecoderException
at org.apache.commons.httpclient.HttpMethodBase.<init>(HttpMethodBase.java:220)
at org.apache.commons.httpclient.methods.GetMethod.<init>(GetMethod.java:89)
at Httpclient.main(Httpclient.java:17)
