Explore the technical principles of Apache Commons Digest frame in the Java library

Apache Commons Digester is an open source framework for analyzing XML files and converting it into Java objects.It provides a simple and powerful way to process XML data and map it to an object model in the Java library. Below is a simple example of using Apache Commons Digester to analyze XML files: First of all, we need to define a Java class as an object model to be maximized.Suppose we want to analyze the following xml files: <book> <Title> Java Programming </Title> <emor> Zhang San </author> <price>25.0</price> </book> public class Book { private String title; private String author; private double price; // The Getter and SETTER method of omitting attributes @Override public String toString() { return "Book{" + "title='" + title + '\'' + ", author='" + author + '\'' + ", price=" + price + '}'; } } Next, we need to create a DIGESTER object and configure the rules to match the relationship between XML nodes and Java objects.In this example, we will use the name of the XML node name to match the name of the Java object attribute name: public class DigesterExample { public static void main(String[] args) throws Exception { Digester digester = new Digester(); // Configuration rules digester.setValidating(false); // Configure the rules, mapping the <book> node as a BOOK object digester.addObjectCreate("book", Book.class); // Configure the rules, mapping the content of the <Title> node as the title property of the BOOK object digester.addCallMethod("book/title", "setTitle", 0); // Configure rules, map the content of the <UTHOR> node as the Author property of the BOOK object digester.addCallMethod("book/author", "setAuthor", 0); // Configure rules, map the content of the <Price> node as the Price property of the BOOK object digester.addCallMethod("book/price", "setPrice", 0); // Analyze the XML file and get the Java object Book book = (Book) digester.parse(new File("book.xml")); // Print java objects System.out.println(book); } } In the above sample code, we first created a Digest object, and then configured some rules.Finally, we analyze the XML file by calling the `Parse` method and obtain the parsing Java object.Finally, the Java object can be printed to verify the correctness of the analysis. To sum up, the Apache Commons Digester framework analyzes the XML file by defining a set of rules and converts it into a Java object.This rules are established with XML nodes and corresponding Java objects, making the parsing process simple and powerful.Using Digester, we can easily process XML data and convert it into an object model that can be processed in the Java class library.