统计所有成功访问的站点。成功与否根据第四列的值进行判断，如果第四列的值是TCP_DENIED/302 则访问不成功，其他情况视为成功。通过实现提供的LogAnalyzer.java中的countSucessfulSites方法完成，无需考虑顺序-Statistics of all successful visit to the site. The success of column values in accordance with the fourth judge, if the fourth column is the value is TCP_DENIED/302 visit is unsuccessful, other circumstances regarded as successful. LogAnalyzer.java provided through the realization of countSucessfulSites method without considering the order of