Java实现的基于模板的网页结构化信息精准抽取组件：HtmlExtractor

HtmlExtractor是为大规模分布式环境设计的，采用主从架构，主节点负责维护抽取规则，从节点向主节点请求抽取规则，当抽取规则发生变化，主节点主动通知从节点，从而能实现抽取规则变化之后的实时动态生效。

如何使用？

    HtmlExtractor由2个子项目构成，html-extractor和html-extractor-web。
html-extractor实现了数据抽取逻辑，是从节点，html-extractor-web提供web界面来维护抽取规则，是主节点。
html-extractor是一个jar包，可通过maven引用：

<dependency>
    <groupId>org.apdplat</groupId>
    <artifactId>html-extractor</artifactId>
    <version>1.0</version>
</dependency>

      html-extractor-web是一个war包，需要部署到Servlet/Jsp容器上。 

单机集中式使用方法：

//1、构造抽取规则

List<UrlPattern> urlPatterns = new ArrayList<>();
//1.1、构造URL模式
UrlPattern urlPattern = new UrlPattern();
urlPattern.setUrlPattern("http://money.163.com/\\d{2}/\\d{4}/\\d{2}/[0-9A-Z]{16}.html");
//1.2、构造HTML模板
HtmlTemplate htmlTemplate = new HtmlTemplate();
htmlTemplate.setTemplateName("网易财经频道");
htmlTemplate.setTableName("finance");
//1.3、将URL模式和HTML模板建立关联
urlPattern.addHtmlTemplate(htmlTemplate);
//1.4、构造CSS路径
CssPath cssPath = new CssPath();
cssPath.setCssPath("h1");
cssPath.setFieldName("title");
cssPath.setFieldDescription("标题");
//1.5、将CSS路径和模板建立关联
htmlTemplate.addCssPath(cssPath);
//1.6、构造CSS路径
cssPath = new CssPath();
cssPath.setCssPath("div#endText");
cssPath.setFieldName("content");
cssPath.setFieldDescription("正文");
//1.7、将CSS路径和模板建立关联
htmlTemplate.addCssPath(cssPath);
//可象上面那样构造多个URLURL模式
urlPatterns.add(urlPattern);

//2、获取抽取规则对象
ExtractRegular extractRegular = ExtractRegular.getInstance(urlPatterns);
//注意：可通过如下3个方法动态地改变抽取规则
//extractRegular.addUrlPatterns(urlPatterns);
//extractRegular.addUrlPattern(urlPattern);
//extractRegular.removeUrlPattern(urlPattern.getUrlPattern());

//3、获取HTML抽取工具
HtmlExtractor htmlExtractor = HtmlExtractor.getInstance(extractRegular);

//4、抽取网页
String url = "http://money.163.com/08/1219/16/4THR2TMP002533QK.html";
List<ExtractResult> extractResults = htmlExtractor.extract(url, "gb2312");

//5、输出结果
int i = 1;
for (ExtractResult extractResult : extractResults) {
    System.out.println((i++) + "、网页 " + extractResult.getUrl() + " 的抽取结果");
    for(ExtractResultItem extractResultItem : extractResult.getExtractResultItems()){
        System.out.print("\t"+extractResultItem.getField()+" = "+extractResultItem.getValue());              
    }
    System.out.println("\tdescription = "+extractResult.getDescription());
    System.out.println("\tkeywords = "+extractResult.getKeywords());
}

多机分布式使用方法：

    1、运行主节点，负责维护抽取规则：
  将子项目html-extractor-web打成War包然后部署到Tomcat。
2、获取一个HtmlExtractor的实例（从节点），示例代码如下：

String allExtractRegularUrl = "http://localhost:8080/HtmlExtractorServer/api/all_extract_regular.jsp";
String redisHost = "localhost";
int redisPort = 6379;
HtmlExtractor htmlExtractor = HtmlExtractor.getInstance(allExtractRegularUrl, redisHost, redisPort);

    3、抽取信息，示例代码如下：

String url = "http://money.163.com/08/1219/16/4THR2TMP002533QK.html";
List<ExtractResult> extractResults = htmlExtractor.extract(url, "gb2312");

int i = 1;
for (ExtractResult extractResult : extractResults) {
    System.out.println((i++) + "、网页 " + extractResult.getUrl() + " 的抽取结果");
    for(ExtractResultItem extractResultItem : extractResult.getExtractResultItems()){
        System.out.print("\t"+extractResultItem.getField()+" = "+extractResultItem.getValue());              
    }
    System.out.println("\tdescription = "+extractResult.getDescription());
    System.out.println("\tkeywords = "+extractResult.getKeywords());
}