In -depth understanding of the old version of the JAXB Runtime framework in the Java class library: architecture and principle
In -depth understanding of the old version of the JAXB Runtime framework in the Java class library: architecture and principle
Introduction:
JAXB (Java Architecture for XML Binding) is a technology on the Java platform for mutual conversion between XML data and Java objects.JAXB provides a simple and fast way to perform binding operations between XML and Java objects. It can help developers process XML data without manually writing complex XML parsing and generating code.The old version of the JAXB Runtime framework refers to the JAXB implementation version before the JDK 1.6, which contains the class and interfaces required by the environment of the JAXB.
Architecture:
The JAXB Runtime framework contains the following core components:
1. JAXB context (JAXB Context): In the JAXB application, you must first create a JAXB context.The context of JAXB is the main entrance point in the JAXB framework. It maintains the configuration information required by the JAXB application, such as the mapping relationship between the Java class and the XML mode file.
2. Binding Tool: JAXB provides a command line tool (XJC) to generate the Java class according to the XML mode file.This binding tool converts the XML mode definition (XSD) into the Java class to convey between XML and Java objects at runtime.Developers can use the tool's Java API for automation generation.
3. Annotations: The JAXB framework controls the behavior of the binding operation by using the annotation.Developers can use different annotations in the Java class to customize the formats of the generated XML documents, such as the name of the specified element, name space, order, etc.
4. Data Binder: JAXB provides a data binder for data conversion between Java objects and XML.The data binder is responsible for serializing the data of the Java object from the memory to the XML format, and the XML data is serialized to the Java object.
principle:
The working principle of the JAXB framework is as follows:
1. Create through JAXB context: First, through the static factory method of the JAXB context class, such as `javax.xml.bind.jaxbcontext.newinstance ()`, create a jaxb contest example.You can pass the Java class and other configuration information to the context that needs to be binding.
2. Binding operation: In the context of the JAXB, use the binding tool (XJC) to generate the Java code, and the binding operation is performed.The binding tool analyzes the XSD file, and the corresponding Java class and interfaces are generated according to the element and type definition.
3. Data binding: Convert XML data and Java objects, and you can use the data binder to complete.The data binder provides a set of APIs to read and write XML data.By calling the `Marshal () method of the data binder, the Java object can be serialized to XML format; by calling the` unmarshal () method, the XML data can be sequenced into Java objects.
Example code:
Below is a simple example code that demonstrates how to use JAXB to serialize and deepen Java objects and XML data.
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;
import java.io.StringReader;
import java.io.StringWriter;
@XmlRootElement
class Person {
private String name;
private int age;
@XmlElement
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@XmlElement
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
}
public class JAXBExample {
public static void main(String[] args) throws JAXBException {
// Create jaxb context
JAXBContext jaxbContext = JAXBContext.newInstance(Person.class);
// Create Marshaller and Unmarshaller
Marshaller marshaller = jaxbContext.createMarshaller();
Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();
// Create a Person object
Person person = new Person();
person.setName("Alice");
person.setAge(25);
// Sequence the Java object to XML
StringWriter writer = new StringWriter();
marshaller.marshal(person, writer);
String xml = writer.toString();
System.out.println("Serialized XML: " + xml);
// Turn the XML back series to Java object
StringReader reader = new StringReader(xml);
Person deserializedPerson = (Person) unmarshaller.unmarshal(reader);
System.out.println("Deserialized Person: " + deserializedPerson.getName() + ", " + deserializedPerson.getAge());
}
}
This sample code shows how to create a simple Person class, uses JAXB to sequence the object to XML, and then the back serialization into a Java object.
in conclusion:
The JAXB Runtime framework is a technology on the Java platform to process XML data and Java objects.Through in -depth understanding of the architecture and principles of the JAXB framework, developers can process XML data more efficiently and easily, and transform and interact with the Java object.
