软件工程专业毕业论文--主题网络爬虫的设计与实现.docVIP

摘　要 目前信息网上蕴含了大量的信息，但通过人工浏览的方法很难做到对信息的安全浏览、整理，很多有用的信息也就白白流失，产生了大量信息不能及时应用的矛盾，给用户造成了很大的不便，为了解决这一问题，有哪些信誉好的足球投注网站引擎这一新热点技术应运而生，本文结合信息网的特征，运用信息抽取和网页解析技术，设计和实现了有哪些信誉好的足球投注网站引擎中最重要的部分——网络爬虫，以提供分类更细致精确、数据更全面深入、更新更及时的因特网有哪些信誉好的足球投注网站服务。 本文首先对概述了网络爬虫的发展概况，然后分析了网络爬虫的体系结构以及实现原理，并深入分析了主题页面在Web上的分布特征与主题相关性的判别算法，具体工作如下： (1)爬虫部分，通过设计种子网站进行爬虫，下载尽可能全且与用户要求相符合的网站。 (2)网页预处理过程，包括分词、HTML解析和网页消噪。在对树节点进行裁剪的基础上，设计了基于样式的网页消噪方法，进一步提高网页消噪过程。 (3)主题相关性判断，包括特征提取和权值计算阶段。在特征提取阶段，通过组合文档频率，得到新的特征，达到降维和提高分类精度的效果。在权值计算阶段，结合信息增益、传统TFIDF算法和空间向量模型VSM算法，得到了更适合主题相关性判断的权值计算方法。 (4)最后，在MYECLIPSE平台上，实现了一个简易的网络爬虫系统，并简要分析了爬虫的运行效果，达到了令人满意的效果。 关键词：网页解析；TFIDF算法；VSM算法 Abstract Currently there is lot of information in the public security information website,but it is not possible to visit and clean up all information only through artifical manner,so much import information would be lost,also would go aginst cracking a criminal case,which causes a great deal of inconvenience to users.To deal with this problem,search engine technology came into being the new hot spot.Based on the characteristics of information networks,the paper designed and implemented the most important part of search engine—Web Spider，using information extraction and web analytic technology to provide more detailed classification accuracy, data is more comprehensive and in-depth, more timely updates of Internet search services. This paper first outlined the development of search engines and reptile research network status and then analyzed the architecture of topic search engine and depthly analysd the theme of the page in the Web on the distribution of subject characteristics and the identification algorithm.In this paper,the concrete work as follows: (1)Spider part. By set seeds through the design of website, download as much as possible and with the whole site in line with user requirements. (2)Page pre-processing process, including Word particiling, HTML parsing and page de-noising. (3) To determine the relevance of the theme, including the feature extraction stage and the righ