Use Apache Commons Digerster to simplify the development process of the Java class library (Simplifying Java Class Library Development with Apache Commons Digester)
Use Apache Commons Digester to simplify the development process of the Java class library
Summary:
During the development of the Java library, data analysis is a common demand.Apache Commons Digester is a powerful tool that helps developers to simplify the process of data analysis.This article will introduce the use of the Apache Commons Digestter framework, and how to use it to simplify the development process of the Java library.
1 Introduction
Apache Commons Digester is an open source analysis framework based on the Java language, which aims to help developers analyze and mapping XML and text files to Java objects.It uses the SAX event driver model and maps XML or text data as a Java object through the use of rules.
2. Installation and configuration
In order to use Apache Commonts Digerster, you first need to download and install the Digerster library.You can find the latest versions on the DIGESTER page of Apache's official website and download the corresponding jar file.Once the jar file is added to the project's classpath, you can start using Digestter in the Java code.
3. The core concept of DIGESTER
Before starting to use Digester, you need to understand some of the core concepts of the Digerster:
-Digester: The DIGESTER object is the entrance point of the entire framework, which is responsible for creating and managing the entire parsing process.
-Rule: Rule objects are used to specify how to deal with events in the process of analysis.DIGESTER can use the default rules or custom rules.
-Pattern: Pattern is used to specify the path of XML or text data that needs to be matched.Digester will decide which rule is used for processing according to pattern.
4. Use DIGESTER for XML analysis
Suppose we have a XML file as shown below:
<books>
<book>
<Title> Java Programming Thought </Title>
<author>Bruce Eckel</author>
</book>
<book>
<Title> Design Mode </Title>
<author>Erich Gamma</author>
</book>
</books>
We can use Digester to parse this XML file and map it as a Java object.First of all, you need to create a book class to represent the information of each book:
public class Book {
private String title;
private String author;
// omit the constructor and getter/setter method
@Override
public String toString() {
return "Book [title=" + title + ", author=" + author + "]";
}
}
Then, you can write the following code to use the DIGESTER for XML parsing:
import org.apache.commons.digester3.Digester;
public class XmlParser {
public static void main(String[] args) throws Exception {
Digester digester = new Digester();
digester.addObjectCreate("books/book", Book.class);
digester.addBeanPropertySetter("books/book/title", "title");
digester.addBeanPropertySetter("books/book/author", "author");
digester.addSetNext("books/book", "add");
List<Book> books = new ArrayList<>();
digester.push(books);
File xmlFile = new File("books.xml");
digester.parse(xmlFile);
for (Book book : books) {
System.out.println(book);
}
}
}
In the above code, we first created a Digerster object.Next, we use the AdDObjectCreate method to tell Digerster to create a Book object when encountering the "Books/Book" path.Then, we map the "Title" and "Author" properties to the corresponding elements in the XML file through the addBeanpropertySetter method.Finally, we use the addsetnext method to add each analytical Book object to a list.
Through the above code, you can successfully analyze the XML file and map it as a Java object.In the end, the printed results will be information about two books.
5 Conclusion
Apache Commons Digestter is a very useful tool that can help developers simplify data analysis during the development of the Java class library.This article introduces the use of the DIGESTER framework and provides an example of using Digerster for XML parsing.Use Digester to process XML and text data more easily, thereby speeding up the speed and efficiency of the development of the class library.
Reference materials:
-Apache Commons Digester official website: http://commons.apache.org/proper/Commons-digerster/
-Apache Commons Digerster User Guide: http://commons.apache.org/proper/commons-digester/guide/core.html
