Guide to use the HTML parser framework in the Java class library
Guide to use the HTML parser framework in the Java class library
Introduction:
The HTML parser framework is a tool for analyzing and processing HTML documents in the Java class library.It allows developers to extract data from HTML and operate the structure and content of the document.This article will introduce how to use the HTML parser framework in the Java library to process HTML documents.
1. Introduce the HTML parser frame library
First, you need to add the HTML parser framework library to your Java project.A commonly used HTML parser framework is JSOUP.You need to download the jar file of the jsoup library and import it into your project.
2. Create HTML document object
Next, you need to create an HTML document object so that you can extract data and operate document content from HTML.You can use JSOUP's `Connect (URL)" method to load a remote HTML page, or use the `PARSE (HTML)" method to analyze a local HTML file.
For example, you can use the following code to load a remote HTML page:
Document doc = Jsoup.connect("http://www.example.com").get();
Or, you can use the following code to analyze a local HTML file:
File input = new File("path/to/input.html");
Document doc = Jsoup.parse(input, "UTF-8", "http://example.com/");
3. Extract data
Once you get an HTML document object, you can use various methods to extract data from the document.Here are some common data extraction operations:
-Cap the page title:
String title = doc.title();
System.out.println("Title: " + title);
-Colon all the links:
Elements links = doc.select("a[href]");
for (Element link : links) {
String href = link.attr("href");
System.out.println("Link: " + href);
}
-Colon the content of the specified element:
Element element = doc.getElementById("someId");
String content = element.text();
System.out.println("Content: " + content);
-Colon the content of the specified label:
Elements elements = doc.getElementsByTag("p");
for (Element element : elements) {
String content = element.text();
System.out.println("Paragraph: " + content);
}
4. Operation HTML document
In addition to extracting data, you can also use the HTML parser framework to operate the structure and content of the document.Here are some commonly used operations:
-Ad the element:
Element newElement = doc.createElement("div");
newElement.text("This is a new element");
doc.body().appendChild(newElement);
-Codd the element attribute:
Element element = doc.getElementById("someId");
element.attr("href", "http://www.example.com");
-State the element:
Element element = doc.getElementById("someId");
element.remove();
-Codd the content of the element:
Element element = doc.getElementById("someId");
element.text("New content");
5. Output HTML document
Once you complete the handling of the HTML document, you can save the modified document as an HTML file or output in the form of a string.
-State to HTML file:
File output = new File("path/to/output.html");
FileOutputStream fos = new FileOutputStream(output);
OutputStreamWriter osw = new OutputStreamWriter(fos, "UTF-8");
osw.write(doc.outerHtml());
osw.close();
-Outs as string:
String html = doc.outerHtml();
System.out.println(html);
Summarize:
The HTML parser framework is a powerful tool for analysis and processing HTML documents in the Java class library.This article introduces how to use the HTML parser framework in the Java class library to extract data, operating documents and output HTML documents.By using the use of the HTML parser framework, you can easily handle and operate HTML documents and implement various HTML -based applications.
