Interpretation of the source code of the HTML parser framework in the Java class library
HTML parser is a tool or library for analysis and extraction of information in the HTML document.There are many powerful HTML parser frameworks in the Java library, the most popular of which is the JSOUP framework.In this article, we will interpret the source code of the JSOUP framework and provide some Java code examples to illustrate its usage.
1. Overview of JSOUP
JSOUP is an open source Java library for handling HTML documents.It provides a simple and flexible API that allows developers to extract and operate data from HTML documents.It can be used for many applications such as crawlers, data extraction, and HTML analysis.
Second, the characteristics of JSOUP
JSOUP has the following features:
1. Analyze and traverse HTML documents: JSOUP can load the HTML document and analyze it as a DOM tree structure. Developers can use the different parts of the tree structure to traverse the document.
2. Selector function: JSOUP supports the syntax similar to the CSS selector, which can help developers choose the HTML element required.
3. Operation HTML element: Developers can use JSOUP to modify the elements, attributes and texts in the HTML document.
4. Safety filtering: JSOUP can help developers filter the illegal or harmful HTML tags and attributes in the user input to prevent cross -site script attack (XSS).
5. Code conversion: JSOUP can automatically handle various characters encoding and convert HTML documents into specified codes.
3. JSOUP source code interpretation
Below we will interpret the source code of the JSOUP framework through several simple examples.
1. Load and analyze the HTML documentation
The following code demonstrates how to use JSOUP to load and analyze the HTML document:
String html = "<html><head><title>Jsoup示例</title></head><body><div id='content'>Hello, Jsoup!</div></body></html>";
Document doc = Jsoup.parse(html);
By calling the `jsoup.parse () method, we can resolve the HTML string into an` DOCument` object, and then use this object to further operate.
2. Selector function
JSOUP's selector function is similar to the CSS selector, which can help us choose the elements in the HTML document.The following code demonstrates how to use the selector to select a certain HTML element:
Elements elements = doc.select("div#content");
String text = elements.text();
System.out.println(text); // Output: Hello, Jsoup!
3. Operation HTML element
Through JSOUP, we can easily operate the content and attributes of the HTML elements very easily.The following code demonstrates how to modify the HTML element:
Element content = doc.getElementById("content");
content.text("Hello, Jsoup! (Modified)");
System.out.println(content.text()); // Output: Hello, Jsoup! (Modified)
Fourth, summary
In this article, the source code interpretation of the HTML parser framework in the Java class library focuses on the characteristics and usage methods of the JSOUP framework.By analyzing the source code of JSOUP, we can better understand and apply the framework to realize the analysis and operation of HTML documents.
In short, JSOUP is a powerful and easy -to -use HTML parser framework, which provides rich APIs and functions for Java developers to meet various HTML processing needs.I hope this article will help you understand and use the HTML parser framework.
