Jaxb2 实现JavaBean与xml互转

一、简介

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。

Jaxb 2.0是JDK 1.6的组成部分。我们不需要下载第三方jar包 即可做到轻松转换。Jaxb2使用了JDK的新特性，如：Annotation、GenericType等，需要在即将转换的JavaBean中添加annotation注解。

二、重要概念

JAXBContext类，是应用的入口，用于管理XML/Java绑定信息。

Marshaller接口，将Java对象序列化为XML数据。

Unmarshaller接口，将XML数据反序列化为Java对象。

@XmlType，将Java类或枚举类型映射到XML模式类型

@XmlAccessorType(XmlAccessType.FIELD) ，控制字段或属性的序列化。FIELD表示JAXB将自动绑定Java类中的每个非静态的（static）、非瞬态的（由@XmlTransient标 注）字段到XML。其他值还有XmlAccessType.PROPERTY和XmlAccessType.NONE。

@XmlAccessorOrder，控制JAXB 绑定类中属性和字段的排序。

@XmlJavaTypeAdapter，使用定制的适配器（即扩展抽象类XmlAdapter并覆盖marshal()和unmarshal()方法），以序列化Java类为XML。

@XmlElementWrapper ，对于数组或集合（即包含多个元素的成员变量），生成一个包装该数组或集合的XML元素（称为包装器）。

@XmlRootElement，将Java类或枚举类型映射到XML元素。

@XmlElement，将Java类的一个属性映射到与属性同名的一个XML元素。

@XmlAttribute，将Java类的一个属性映射到与属性同名的一个XML属性。

三、示例

1、准备工作

Java代码


package utils;

import java.io.StringReader;

import java.io.StringWriter;

import javax.xml.bind.JAXBContext;

import javax.xml.bind.Marshaller;

import javax.xml.bind.Unmarshaller;

/**

* Jaxb2工具类

* @author zhuc

* @create 2013-3-29 下午2:40:14

*/

public class JaxbUtil {

/**

* JavaBean转换成xml

* 默认编码UTF-8

* @param obj

* @param writer

* @return

*/

public static String convertToXml(Object obj) {

return convertToXml(obj, "UTF-8");

}

/**

* JavaBean转换成xml

* @param obj

* @param encoding

* @return

*/

public static String convertToXml(Object obj, String encoding) {

String result = null;

try {

JAXBContext context = JAXBContext.newInstance(obj.getClass());

Marshaller marshaller = context.createMarshaller();

marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);

marshaller.setProperty(Marshaller.JAXB_ENCODING, encoding);

StringWriter writer = new StringWriter();

marshaller.marshal(obj, writer);

result = writer.toString();

} catch (Exception e) {

e.printStackTrace();

}

return result;

}

/**

* xml转换成JavaBean

* @param xml

* @param c

* @return

*/

@SuppressWarnings("unchecked")

public static <T> T converyToJavaBean(String xml, Class<T> c) {

T t = null;

try {

JAXBContext context = JAXBContext.newInstance(c);

Unmarshaller unmarshaller = context.createUnmarshaller();

t = (T) unmarshaller.unmarshal(new StringReader(xml));

} catch (Exception e) {

e.printStackTrace();

}

return t;

}

}

非常简单易懂，需要注意的是

Java代码


marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);

marshaller.setProperty(Marshaller.JAXB_ENCODING, encoding);

Marshaller.JAXB_FORMATTED_OUTPUT 决定是否在转换成xml时同时进行格式化（即按标签自动换行，否则即是一行的xml）

Marshaller.JAXB_ENCODING xml的编码方式

另外，Marshaller 还有其他Property可以设置，可以去查阅api。

2、最简单转换

Java代码


package t1;

import java.util.Date;

import javax.xml.bind.annotation.XmlAccessType;

import javax.xml.bind.annotation.XmlAccessorType;

import javax.xml.bind.annotation.XmlAttribute;

import javax.xml.bind.annotation.XmlElement;

import javax.xml.bind.annotation.XmlRootElement;

import javax.xml.bind.annotation.XmlType;

/**

* @author zhuc

* @create 2013-3-29 下午2:49:48

*/

@XmlAccessorType(XmlAccessType.FIELD)

@XmlRootElement

@XmlType(name = "book", propOrder = { "author", "calendar", "price", "id" })

public class Book {

@XmlElement(required = true)

private String author;

@XmlElement(name = "price_1", required = true)

private float price;

@XmlElement

private Date calendar;

@XmlAttribute

private Integer id;

/**

* @return the author

*/

public String getAuthor() {

return author;

}

/**

* @return the price

*/

public float getPrice() {

return price;

}

/**

* @return the calendar

*/

public Date getCalendar() {

return calendar;

}

/**

* @return the id

*/

public Integer getId() {

return id;

}

/**

* @param author the author to set

*/

public void setAuthor(String author) {

this.author = author;

}

/**

* @param price the price to set

*/

public void setPrice(float price) {

this.price = price;

}

/**

* @param calendar the calendar to set

*/

public void setCalendar(Date calendar) {

this.calendar = calendar;

}

/**

* @param id the id to set

*/

public void setId(Integer id) {

this.id = id;

}

/* (non-Javadoc)

* @see java.lang.Object#toString()

*/

@Override

public String toString() {

return "Book [author=" + author + ", price=" + price + ", calendar=" + calendar + ", id=" + id + "]";

}

}

Java代码


package t1;

import java.util.Date;

import javax.xml.bind.JAXBException;

import org.junit.Test;

import utils.JaxbUtil;

/**

* @author zhuc

* @create 2013-3-29 下午2:50:00

*/

public class JaxbTest1 {

/**

* @throws JAXBException

*/

@Test

public void showMarshaller() {

Book book = new Book();

book.setId(100);

book.setAuthor("James");

book.setCalendar(new Date());

book.setPrice(23.45f); //默认是0.0

String str = JaxbUtil.convertToXml(book);

System.out.println(str);

}

/**

* @throws JAXBException

*/

@Test

public void showUnMarshaller() {

String str = "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?>" +

"<book id=\"100\">" +

" <author>James</author>" +

" <calendar>2013-03-29T09:25:56.004+08:00</calendar>" +

" <price_1>23.45</price_1>" +

"</book>";

Book book = JaxbUtil.converyToJavaBean(str, Book.class);

System.out.println(book);

}

}

输出结果分别为：

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>

<book id="100">

<author>James</author>

<calendar>2013-03-29T14:50:58.974+08:00</calendar>

<price_1>23.45</price_1>

</book>

Book [author=James, price=23.45, calendar=Fri Mar 29 09:25:56 CST 2013, id=100]

3、类中包含复杂对象的转换

Java代码


package t2;

import javax.xml.bind.annotation.XmlAccessType;

import javax.xml.bind.annotation.XmlAccessorType;

import javax.xml.bind.annotation.XmlAttribute;

import javax.xml.bind.annotation.XmlElement;

import javax.xml.bind.annotation.XmlRootElement;

import javax.xml.bind.annotation.XmlType;

/**

* @author zhuc

* @create 2013-3-29 下午2:51:44

*/

@XmlAccessorType(XmlAccessType.FIELD)

@XmlRootElement(name = "student")

@XmlType(propOrder = {})

public class Student {

@XmlAttribute

private Integer id;

@XmlElement

private String name;

@XmlElement(name = "role")

private Role role;

/**

* @return the id

*/

public Integer getId() {

return id;

}

/**

* @return the name

*/

public String getName() {

return name;

}

/**

* @return the role

*/

public Role getRole() {

return role;

}

/**

* @param id the id to set

*/

public void setId(Integer id) {

this.id = id;

}

/**

* @param name the name to set

*/

public void setName(String name) {

this.name = name;

}

/**

* @param role the role to set

*/

public void setRole(Role role) {

this.role = role;

}

/* (non-Javadoc)

* @see java.lang.Object#toString()

*/

@Override

public String toString() {

return "Student [id=" + id + ", name=" + name + ", role=" + role + "]";

}

}

Java代码


package t2;

import javax.xml.bind.annotation.XmlAccessType;

import javax.xml.bind.annotation.XmlAccessorType;

import javax.xml.bind.annotation.XmlElement;

import javax.xml.bind.annotation.XmlType;

/**

* @author zhuc

* @create 2013-3-29 下午2:51:52

*/

@XmlAccessorType(XmlAccessType.FIELD)

@XmlType(propOrder = { "name", "desc" })

public class Role {

@XmlElement

private String name;

@XmlElement

private String desc;

/**

* @return the name

*/

public String getName() {

return name;

}

/**

* @return the desc

*/

public String getDesc() {

return desc;

}

/**

* @param name the name to set

*/

public void setName(String name) {

this.name = name;

}

/**

* @param desc the desc to set

*/

public void setDesc(String desc) {

this.desc = desc;

}

/* (non-Javadoc)

* @see java.lang.Object#toString()

*/

@Override

public String toString() {

return "Role [name=" + name + ", desc=" + desc + "]";

}

}

Java代码


package t2;

import org.junit.Test;

import utils.JaxbUtil;

/**

* @author zhuc

* @create 2013-3-29 下午2:52:00

*/

public class JaxbTest2 {

@Test

public void showMarshaller() {

Student student = new Student();

student.setId(12);

student.setName("test");

Role role = new Role();

role.setDesc("管理");

role.setName("班长");

student.setRole(role);

String str = JaxbUtil.convertToXml(student);

System.out.println(str);

}

@Test

public void showUnMarshaller() {

String str = "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?>"+

"<student id=\"12\">"+

" <name>test</name>"+

" <role>"+

" <name>班长</name>"+

" <desc>管理</desc>"+

"</role>"+

"</student>";

Student student = JaxbUtil.converyToJavaBean(str, Student.class);

System.out.println(student);

}

}

输出结果分别为：

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>

<student id="12">

<name>test</name>

<role>

<name>班长</name>

<desc>管理</desc>

</role>

</student>

Student [id=12, name=test, role=Role [name=班长, desc=管理]]

4、集合对象的转换（同样适用于Set）

Java代码


package t3;

import java.util.List;

import javax.xml.bind.annotation.XmlAccessType;

import javax.xml.bind.annotation.XmlAccessorType;

import javax.xml.bind.annotation.XmlElement;

import javax.xml.bind.annotation.XmlElementWrapper;

import javax.xml.bind.annotation.XmlRootElement;

import javax.xml.bind.annotation.XmlType;

/**

* @author zhuc

* @create 2013-3-29 下午2:55:56

*/

@XmlAccessorType(XmlAccessType.FIELD)

@XmlRootElement(name = "country")

@XmlType(propOrder = { "name", "provinceList" })

public class Country {

@XmlElement(name = "country_name")

private String name;

@XmlElementWrapper(name = "provinces")

@XmlElement(name = "province")

private List<Province> provinceList;

/**

* @return the name

*/

public String getName() {

return name;

}

/**

* @return the provinceList

*/

public List<Province> getProvinceList() {

return provinceList;

}

/**

* @param name the name to set

*/

public void setName(String name) {

this.name = name;

}

/**

* @param provinceList the provinceList to set

*/

public void setProvinceList(List<Province> provinceList) {

this.provinceList = provinceList;

}

/* (non-Javadoc)

* @see java.lang.Object#toString()

*/

@Override

public String toString() {

return "Country [name=" + name + ", provinceList=" + provinceList + "]";

}

}

Java代码


package t3;

import javax.xml.bind.annotation.XmlAccessType;

import javax.xml.bind.annotation.XmlAccessorType;

import javax.xml.bind.annotation.XmlElement;

import javax.xml.bind.annotation.XmlType;

/**

* @author zhuc

* @create 2013-3-29 下午2:56:03

*/

@XmlAccessorType(XmlAccessType.FIELD)

@XmlType(propOrder = { "name", "provCity" })

public class Province {

@XmlElement(name = "province_name")

private String name;

@XmlElement(name = "prov_city")

private String provCity;

/**

* @return the provCity

*/

public String getProvCity() {

return provCity;

}

/**

* @param provCity the provCity to set

*/

public void setProvCity(String provCity) {

this.provCity = provCity;

}

/**

* @return the name

*/

public String getName() {

return name;

}

/**

* @param name the name to set

*/

public void setName(String name) {

this.name = name;

}

/* (non-Javadoc)

* @see java.lang.Object#toString()

*/

@Override

public String toString() {

return "Province [name=" + name + ", provCity=" + provCity + "]";

}

}

Java代码


package t3;

import java.util.ArrayList;

import java.util.List;

import org.junit.Test;

import utils.JaxbUtil;

/**

* @author zhuc

* @create 2013-3-29 下午2:56:11

*/

public class JaxbTest3 {

/**

* @throws JAXBException

*/

@Test

public void showMarshaller() {

Country country = new Country();

country.setName("中国");

List<Province> list = new ArrayList<Province>();

Province province = new Province();

province.setName("江苏省");

province.setProvCity("南京市");

Province province2 = new Province();

province2.setName("浙江省");

province2.setProvCity("杭州市");

list.add(province);

list.add(province2);

country.setProvinceList(list);

String str = JaxbUtil.convertToXml(country);

System.out.println(str);

}

/**

*

*/

@Test

public void showUnMarshaller() {

String str = "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?>"+

"<country>"+

" <country_name>中国</country_name>"+

" <provinces>"+

" <province>"+

" <province_name>江苏省</province_name>"+

" <prov_city>南京市</prov_city>"+

" </province>"+

" <province>"+

" <province_name>浙江省</province_name>"+

" <prov_city>杭州市</prov_city>"+

" </province>"+

" </provinces>"+

"</country>";

Country country = JaxbUtil.converyToJavaBean(str, Country.class);

System.out.println(country);

}

}

输出结果分别为：

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>

<country>

<country_name>中国</country_name>

<provinces>

<province>

<province_name>江苏省</province_name>

<prov_city>南京市</prov_city>

</province>

<province>

<province_name>浙江省</province_name>

<prov_city>杭州市</prov_city>

</province>

</provinces>

</country>

Country [name=中国, provinceList=[Province [name=江苏省, provCity=南京市], Province [name=浙江省, provCity=杭州市]]]