Data conversion techniques between the Commons DIGESTER framework and the Java class library

The Commons Digester framework is a commonly used Java open source library that is used to convert XML data to Java objects.It provides a simple and flexible way to analyze XML and automatically map it as the attribute of the Java object.In this article, we will introduce how to use the Commons Digester framework to implement data conversion techniques in the Java library, and provide Java code example for the situation. 1. Overview of the Commons Digester framework The Commons Digester framework is based on the parser design mode and analyzes XML data by using event drive.It can realize the starting element, analyze the XML node step by step, and map it as the attribute of the Java object.This allows to avoid writing a large number of parsing code when processing XML data, which greatly improves development efficiency. Second, use the Commons Digester framework to achieve data conversion The following is the general step of using the Commons Digestter framework to implement data conversion: 1. Create a Digestter object: First of all, you need to create a Digetter object, which will be responsible for analysis of XML data and map it as a Java object. Digester digester = new Digester(); 2. Configure the DIGESTER object: Next, you need to configure the rules for the DIGESTER object to tell it how to analyze XML data. digester.addRule("rootElement", new ObjectCreateRule(RootElement.class)); digester.addBeanPropertySetter("rootElement/attribute1", "attribute1"); digester.addSetNext("rootElement", "setRootElement"); In the above code, first use the `addrule ()` method to create a rule, specify the analysis method of root element, `rooted.class` is a Java class corresponding to the root element.Then use the method to configure the attribute analysis rule to configure the attribute to the method of the xml element in the attribute of the Java object.Finally, use the `addsetnext ()` method to add the parsed Java object to the parent object. 3. Analysis of XML data: By calling the `PARSE ()" method of the DIGESTER object, XML data can be parsed as the Java object. RootElement rootElement = digester.parse(xmlFile); In the above code, `xmlfile` is a file that is to be parsed to XML data.After the analysis is completed, you can get the Java object corresponding to the root element `rootElement`. Third, sample code The following is a simple example to demonstrate how to use the Commons Digest framework to achieve data conversion. Suppose we have the following xml data: <user> <name>John Doe</name> <age>25</age> <email>john.doe@example.com</email> </user> We hope to convert the above XML data into the following examples of the Java class: public class User { private String name; private int age; private String email; // Getters and setters // ... } Using the Commons Digester framework, we can handle it like this: Digester digester = new Digester(); digester.addObjectCreate("user", User.class); digester.addBeanPropertySetter("user/name", "name"); digester.addBeanPropertySetter("user/age", "age"); digester.addBeanPropertySetter("user/email", "email"); User user = digester.parse(xmlFile); In the above code, we created a distester object and configured rules to analyze XML data.Then, by calling the `PARSE ()" method, the XML data is parsed as an instance of the Java class `user`. Fourth, summary Using the Commons Digester framework can easily implement the conversion between the Java class library and XML data.By configuring the rules of the Digester object, the XML data can be easily mapped as the attribute of the Java object.This provides a simple and flexible way to process XML data and improves development efficiency. The above is the introduction of the data conversion skills between the Commons Digest frame and the Java class library. In the case of need, we also provide a simple example code, hoping to help you.