XML 和 java对象相互转换

Unmarshaller 类使客户端应用程序能够将 XML 数据转换为 Java 内容对象树。

备注：marshal(序列化、排列、整理)

Marshaller 类使客户端应用程序能够将 Java 内容树转换回 XML 数据。

package hb.jaxb;

public class Classroom {
	private int id;
	private String name;
	private int grade;

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public int getGrade() {
		return grade;
	}

	public void setGrade(int grade) {
		this.grade = grade;
	}

	public Classroom(int id,String name,int grade) {
		super();
		this.id = id;
		this.name = name;
		this.grade = grade;
	}

	public Classroom() {
		super();
	}

}

package hb.jaxb;

import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class Student {
	private int id;
	private String name;
	private int age;
	private Classroom classroom;

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}

	public Classroom getClassroom() {
		return classroom;
	}

	public void setClassroom(Classroom classroom) {
		this.classroom = classroom;
	}

	public Student(int id,int age,Classroom classroom) {
		super();
		this.id = id;
		this.name = name;
		this.age = age;
		this.classroom = classroom;
	}

	//无参够着函数一定需要，否则JXBContext无法正常解析。
	public Student() {
		super();
	}
}

注意：

1、需要转换的model对象一定要添加@XmlRootElement注解，其里面的其他对象则不需要

2、需要转换的model对象一定要有不带参数的构造方法，包括该对象里面引用的对象。

package hb.jaxb;

import java.io.StringReader;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;
import org.junit.Test;

public class TestJaxb {

	@Test
	public void beanToXML() {
		Classroom classroom = new Classroom(1,"软件工程",4);
		Student student = new Student(101,"张三",22,classroom);

		try {
			JAXBContext context = JAXBContext.newInstance(Student.class);
			Marshaller marshaller = context.createMarshaller();
			marshaller.marshal(student,System.out);
		} catch (JAXBException e) {
			e.printstacktrace();
		}

	}
	
	@Test
	public void XMLStringToBean(){
		String xmlStr = "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?><student><age>22</age><classroom><grade>4</grade><id>1</id><name>软件工程</name></classroom><id>101</id><name>张三</name></student>";
		try {
			JAXBContext context = JAXBContext.newInstance(Student.class);
			Unmarshaller unmarshaller = context.createUnmarshaller();
			Student student = (Student)unmarshaller.unmarshal(new StringReader(xmlStr));
			System.out.println(student.getAge());
			System.out.println(student.getClassroom().getName());
		} catch (JAXBException e) {
			e.printstacktrace();
		}
		
	}
}