这就是我想要做的: (我想用jsoup)

• 1. 只传递一个 url 进行解析
  2. 搜索网页内容中提到的日期
  3. 从每一页内容中提取至少一个日期
  4. 将该日期转换为标准格式

所以，第 1 点 我现在拥有的:

String url = "http://stackoverflow.com/questions/28149254/using-a-regex-in-jsoup";
Document document = Jsoup.connect(url).get();

现在我想了解“文档”是什么格式，它是否已经从 html 或任何类型的网页类型或什么解析？

然后第 2 点我现在拥有的是:

Pattern p = Pattern.compile("\\d{4}-[01]\\d-[0-3]\\d", Pattern.CASE_INSENSITIVE | Pattern.DOTALL);
Elements elements = document.getElementsMatchingOwnText(p);

在这里，我尝试匹配一个日期正则表达式以在页面中搜索日期并存储在一个字符串中供以后使用(第 3 点)，但我确定我离它不远，这里需要帮助。

我已经完成了第 4 点。

所以请任何可以帮助我理解并引导我走向正确方向的人，我怎样才能实现我上面提到的那 4 点。

提前致谢!

更新: 所以这是我想要的:

public static void main(String[] args){
    try {
        // using USER AGENT for giving information to the server that I am a browser not a bot
        final String USER_AGENT =
                "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/535.1 (KHTML, like Gecko) Chrome/13.0.782.112 Safari/535.1";

        // My only one url which I want to parse
        String url = "http://stackoverflow.com/questions/28149254/using-a-regex-in-jsoup";

        // Creating a jsoup.Connection to connect the url with USER AGENT
        Connection connection = Jsoup.connect(url).userAgent(USER_AGENT);

        // retrieving the parsed document
        Document htmlDocument = connection.get();

        /* Now till this part, I have A parsed document of the url page which is in plain-text format right?
         * If not, in which type or in which format it is stored in the variable 'htmlDocument'
         * */

        /* Now, If 'htmlDocument' holds the text format of the web page
         * Why do i need elements to find dates, because dates can be normal text in a web page,
         * So, how I am going to find an element tag for that?
         * As an example, If i wanted to collect text from <p> paragraph tag, 
         * I would use this : 
         */
        // I am not sure is it correct or not
        //***************************************************/
        Elements paragraph = htmlDocument.getElementsByTag("p");
        for(Element src: paragraph){
            System.out.println("text"+src.attr("abs:p"));
        }
       //***************************************************//

        /* But I do not want any elements to find to gather dates on the page
         * I just want to search the whole text document for date
         * So, I need a regex formatted date string which will be passed as a input for a search method
         * this search mechanism should be on text formatted page as we have parsed document in 'htmlDocument'
         */

        // At the end we will use only one date from our search result and format it in a standard form

        /*
         * That is it.
         */


        /*
         * I was trying something like this
         */
        //final Elements elements = document.getElementsMatchingOwnText("\\d{4}-\\d{2}-\\d{2}");
        Pattern p = Pattern.compile("\\d{4}-[01]\\d-[0-3]\\d", Pattern.CASE_INSENSITIVE | Pattern.DOTALL);
        Elements elements = htmlDocument.getElementsMatchingOwnText(p);

        for(Element e: elements){
            System.out.println("element = [" + e + "]");
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}

最佳答案

这是我找到的一种可能的解决方案:

import org.jsoup.Connection;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

import java.util.List;
import java.util.regex.Pattern;
import java.util.stream.Collectors;

/**
 * Created by ruben.alfarodiaz on 21/12/2016.
 */
@RunWith(JUnit4.class)
public class StackTest {

    @Test
    public void findDates() {
        final String USER_AGENT = "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/535.1 (KHTML, like Gecko) Chrome/13.0.782.112 Safari/535.1";
        try {
            String url = "http://stackoverflow.com/questions/51224/regular-expression-to-match-valid-dates";
            Connection connection = Jsoup.connect(url).userAgent(USER_AGENT);
            Document htmlDocument = connection.get();
            //with this pattern we can find all dates with regex dd/mm/yyyy if we need cover extra formats we should create N more patterns
            Pattern pattern = Pattern.compile("(0?[1-9]|[12][0-9]|3[01])/(0?[1-9]|1[012])/((19|20)\\d\\d)");

            //Here we find all document elements which have some element with the searched pattern  
            Elements elements = htmlDocument.getElementsMatchingText(pattern);
            //in this loop we are going to filter from all original elements to find only the leaf elements
            List<Element> finalElements = elements.stream().filter(elem -> isLastElem(elem, pattern)).collect(Collectors.toList());
            finalElements.stream().forEach(elem ->
                System.out.println("Node: " + elem.html())
            );

        }catch(Exception ex){
            ex.printStackTrace();
        }
    }

    //Method to decide if the current element is a leaf or contains others dates inside  
    private boolean isLastElem(Element elem, Pattern pattern) {
        return elem.getElementsMatchingText(pattern).size() <= 1;
    }

}

应该根据需要添加尽可能多的模式，因为我认为找到一个匹配所有可能性的单一模式会很复杂

编辑:最重要的是库为您提供了元素的层次结构，因此您需要遍历它们以找到最后的叶子。例如

<html>
    <body>
        <div>
           20/11/2017    
        </div>
    </body>
</html>

如果我们找到模式 dd/mm/yyyy 库将返回 3 个元素 html、body 和 div，但我们只对 div 感兴趣

关于java - jsoup : How to search for date text from a webpage，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/41950038/