Commons Digester framework interpretation: important tools in the Java class library
Commons Digester framework interpretation: important tools in the Java class library
Commons Digest is a commonly used tool in Java development to analyze and process XML files.It is an open source framework provided by the Apache Commons project to simplify the analysis and extraction data of the XML file.This article will introduce the basic principles and usage methods of the Commons Digestter framework, and provide some Java code examples to help readers better understand.
1. Basic principle
The basic principle of Commons Digest is based on event -driven parsing models.After analyzing the XML file and detecting a specific XML event, it triggers the pre -registered rules set to handle these events.These rules tell Digest how to map XML data into the Java object.
2. Commonly used functions
1. Analyze XML file: Use Digerster to easily analyze XML files and convert it to Java objects.DIGESTER uses Xpath as a matching rule and position and extract data according to the node path of XML.
Below is a sample xml file:
<person>
<name>John Doe</name>
<age>25</age>
<address>
<street>123 Main St</street>
<city>Exampleville</city>
</address>
</person>
Use Digester to parse the XML file and convert it to the code example of the Java object:
public class Person {
private String name;
private int age;
private Address address;
// Getter and setter methods
}
public class Address {
private String street;
private String city;
// Getter and setter methods
}
public class DigesterExample {
public static void main(String[] args) {
Digester digester = new Digester();
digester.addObjectCreate("person", Person.class);
digester.addBeanPropertySetter("person/name", "name");
digester.addBeanPropertySetter("person/age", "age");
digester.addObjectCreate("person/address", Address.class);
digester.addSetNext("person/address", "setAddress");
digester.addBeanPropertySetter("person/address/street", "street");
digester.addBeanPropertySetter("person/address/city", "city");
File xmlFile = new File("person.xml");
Person person = (Person) digester.parse(xmlFile);
System.out.println(person.getName());
System.out.println(person.getAge());
System.out.println(person.getAddress().getStreet());
System.out.println(person.getAddress().getCity());
}
}
The above code defines a series of rules through DIGESTER, analyzes and maps the XML file to the Java object, and then obtains data by calling the object method.
2. Customized rules: If the default rules of the DIGESTER cannot meet the needs, you can also resolve XML files by custom rules.DIGESTER provides a variety of rules, such as Setnextrule, Setpropertiesrule, CallMethodrule, etc., which can be selected and expanded as needed.
3. Summary
Commons Digest is a very practical tool in Java development, which can simplify the analysis and data extraction process of XML files.By defining based on event -based analysis models and flexible rules, Digerster can map XML data to the Java object and can customize the rules as needed.Developers can flexibly use Digestter to simplify the tedious process of XML processing.
The above is the basic interpretation of the COMMONS DIGESTER framework. I hope it can help readers understand and apply the tool.
