Java class library analysis: in -depth understanding of the COMMONS DIGESTER framework
How to use the framework of the Commons Digestter in -depth
Commons Digest is a Java class library in the Apache Commons project that is used to analyze XML files and convert it into Java objects.It is based on the SAX parser and provides a simple and powerful way to process XML data.
Commons Digest has the following characteristics:
1. Flexible and easy to use: Commons Digerster uses simple strategic patterns and regular configurations to analyze XML files.Developers can create custom rules to resolve complex XML structures.
2. Event -based analysis: Commons Digester analyzes XML by event drive, and the corresponding operation can be performed when specific elements appear.This enables it to efficiently handle large XML files.
3. Support object creation and attribute injection: Commons Digerster can automatically create Java objects according to the structure of the XML element, and map the attributes of the XML element to the attributes of the Java object.In this way, developers can directly convert the XML file into Java objects and operate.
4. Support nested rules: Commons Digerster can handle nested XML structures. By configured nested rules, you can analyze XML elements step by step and create nested objects.
Below is a simple example that demonstrates how to use the Commons Digerster to parse the XML file:
public class Book {
private String title;
private String author;
// getters and setters
@Override
public String toString() {
return "Book [title=" + title + ", author=" + author + "]";
}
}
public class XmlParser {
public static void main(String[] args) throws Exception {
Digester digester = new Digester();
digester.setValidating(false);
digester.addObjectCreate("library/book", Book.class);
digester.addSetProperties("library/book");
digester.addSetNext("library/book", "add");
File file = new File("library.xml");
Library library = (Library) digester.parse(file);
for (Book book : library.getBooks()) {
System.out.println(book);
}
}
}
In the above examples, we first define a book class, indicating a book object.We then created a XMLPARSER class and used the Digerster object to analyze the XML file.Through the DIGESTER.AddObjectCreate () method, we told Digester to create a BOOK object when encountering `Library> <Book>` `` `` `elements.Using the DIGESTER.ADDSETPROPERTIES () method, we map the attributes of the XML element to the attribute of the Book object.Finally, using the DIGESTER.ADDSETNEXT () method, we add the Book objects to the Books set in the library object.
It can be seen that the process of using the Commons DIGESTER framework can simplify the XML parsing process, and it provides a flexible and powerful way to process XML data.
I hope this article can help the use of the in -depth understanding of the Commons Digester framework.
