JAXB 可以实现Java对象与XML的相互转换,在JAXB中,将一个Java对象转换为XML的过程称之为Marshal,将XML转换为Java对象的过程称之为UnMarshal。
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。
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, String name, 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。
3,其中@XmlRootElement(name="Root")表明xml的根元素,(name="Root")这个是重新定义xml文件的跟元素,如果没有此name定义,则xml根元素默认跟对象名一致
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(); } } }
JAXB(Java Architecture for XML Binding) 是一个业界的标准,是一项可以根据XML Schema产生Java类的技术。该过程中,JAXB也提供了将XML实例文档反向生成Java对象树的方法,并能将Java对象树的内容重新写到XML实例文档。从另一方面来讲,JAXB提供了快速而简便的方法将XML模式绑定到Java表示,从而使得Java开发者在Java应用程序中能方便地结合XML数据和处理函数。
JAXBContext 类提供到 JAXB API 的客户端入口点。它提供了管理实现 JAXB 绑定框架操作所需的 XML/Java 绑定信息的抽象,这些操作包括:解组、编组和验证。