JAXB GitHub: https://github.com/javaee/jaxb-v2
JAXB Users Guide : https://javaee.github.io/jaxb-v2/doc/user-guide/ch03.html
JAXB(Java Architecture for XML Binding) 是一個業界的標準,是一項可以根據XML Schema產生Java類的技術。該過程中,JAXB也提供了將XML實例文檔反向生成Java對象樹的方法,並能將Java對象樹的內容重新寫到XML實例文檔。從另一方面來講,JAXB提供了快速而簡便的方法將XML模式綁定到Java表示,從而使得Java開發者在Java應用程序中能方便地結合XML數據和處理函數。
JDK中JAXB相關的重要Class和Interface:
JAXBContext類,是應用的入口,用於管理XML/Java綁定信息。
Marshaller接口,將Java對象序列化爲XML數據。
Unmarshaller接口,將XML數據反序列化爲Java對象。
JDK中JAXB相關的重要Annotation:
- @XmlType,將Java類或枚舉類型映射到XML模式類型
- @XmlAccessorType(XmlAccessType.FIELD) ,控制字段或屬性的序列化。FIELD表示JAXB將自動綁定Java類中的每個非靜態的(static)、非瞬態的(由@XmlTransient標註)字段到XML。其他值還有XmlAccessType.PROPERTY和XmlAccessType.NONE。
- @XmlAccessorOrder,控制JAXB 綁定類中屬性和字段的排序。
- @XmlJavaTypeAdapter,使用定製的適配器(即擴展抽象類XmlAdapter並覆蓋marshal()和unmarshal()方法),以序列化Java類爲XML。
- @XmlElementWrapper ,對於數組或集合(即包含多個元素的成員變量),生成一個包裝該數組或集合的XML元素(稱爲包裝器)。
- @XmlRootElement,將Java類或枚舉類型映射到XML元素。
- @XmlElement,將Java類的一個屬性映射到與屬性同名的一個XML元素。
- @XmlAttribute,將Java類的一個屬性映射到與屬性同名的一個XML屬性。
注意:
- 對於要序列化(marshal)爲XML的Java類,絕不能把成員變量聲明爲public,否則運行將拋出異常com.sun.xml.internal.bind.v2.runtime.IllegalAnnotationsException。
- 對於JAXB相關的重要Annotation的聲明,如@Xml…..,可以放在成員變量的setter()或getter()方法上,兩者中任選其一即可,但決不能放在成員變量上,否則運行將拋出異常com.sun.xml.internal.bind.v2.runtime.IllegalAnnotationsException。
環境要求:JDK1.6+
實例一:
package jaxb;
/**
* Created by sheting on 10/17/2017
*/
public class Classroom {
private int id;
private String name;
private int grade;
public Classroom() {
}
public Classroom(int id, String name, int grade) {
super();
this.id = id;
this.name = name;
this.grade = 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;
}
}
package jaxb;
import javax.xml.bind.annotation.XmlRootElement;
/**
* Created by sheting on 10/17/2017
*/
@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;
}
//無參夠着函數一定需要,否則JXBContext無法正常解析。
public Student() {
super();
}
}
package jaxb;
import org.junit.Test;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;
import java.io.StringReader;
/**
* Created by sheting on 10/17/2017
*/
public class TestJaxb {
@Test
public void beanToXML() {
Classroom classroom = new Classroom(1, "軟件工程", 4);
Student student = new Student(101, "張三", 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>軟件工程</name></classroom><id>101</id><name>張三</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();
}
}
}
注意:
1、需要轉換的model對象一定要添加@XmlRootElement註解,其裏面的其他對象則不需要
2、需要轉換的model對象一定要有不帶參數的構造方法,包括該對象裏面引用的對象。
實例二:
package com.mkyong.core;
import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
@XmlRootElement
public class Customer {
String name;
int age;
int id;
public String getName() {
return name;
}
@XmlElement
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
@XmlElement
public void setAge(int age) {
this.age = age;
}
public int getId() {
return id;
}
@XmlAttribute
public void setId(int id) {
this.id = id;
}
}
Convert Object to XML
package com.mkyong.core;
import java.io.File;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
public class JAXBExample {
public static void main(String[] args) {
Customer customer = new Customer();
customer.setId(100);
customer.setName("mkyong");
customer.setAge(29);
try {
File file = new File("C:\\file.xml");
JAXBContext jaxbContext = JAXBContext.newInstance(Customer.class);
Marshaller jaxbMarshaller = jaxbContext.createMarshaller();
// output pretty printed
jaxbMarshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
jaxbMarshaller.marshal(customer, file);
jaxbMarshaller.marshal(customer, System.out);
} catch (JAXBException e) {
e.printStackTrace();
}
}
}
Output
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<customer id="100">
<age>29</age>
<name>mkyong</name>
</customer>
Convert XML to Object
package com.mkyong.core;
import java.io.File;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Unmarshaller;
public class JAXBExample {
public static void main(String[] args) {
try {
File file = new File("C:\\file.xml");
JAXBContext jaxbContext = JAXBContext.newInstance(Customer.class);
Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();
Customer customer = (Customer) jaxbUnmarshaller.unmarshal(file);
System.out.println(customer);
} catch (JAXBException e) {
e.printStackTrace();
}
}
}
Output
Customer [name=mkyong, age=29, id=100]
維基百科:https://en.wikipedia.org/wiki/Java_Architecture_for_XML_Binding