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

 

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

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

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 + "]";
    }

}

 

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

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 + "]";
    }

}

 

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 + "]";
    }

}

 

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）

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 + "]";
    }

}

 

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 + "]";
    }

}

 

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]]]