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 converyToJavaBean(String xml, Class 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 = "" +
             "" +
             "    James" +
              "   2013-03-29T09:25:56.004+08:00" +
               "  23.45" +
             "";

         Book book = JaxbUtil.converyToJavaBean(str, Book.class);
         System.out.println(book);
     }
 }

 

输出结果分别为：

    James
    2013-03-29T14:50:58.974+08:00
    23.45

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 = ""+
             ""+
             "    test"+
              "   "+
               "      班长"+
                "     管理"+
                 ""+
             "";
         Student student = JaxbUtil.converyToJavaBean(str, Student.class);
         System.out.println(student);
     }

 }

 

输出结果分别为：

    test
   
        班长
        管理
   


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 provinceList;

     /**
      * @return the name
      */
     public String getName() {
         return name;
     }

     /**
      * @return the provinceList
      */
     public List 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 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 list = new ArrayList();
         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 = ""+
             ""+
             "    中国"+
             "    "+
             "        "+
             "            江苏省"+
              "           南京市"+
             "        "+
              "       "+
              "           浙江省"+
              "           杭州市"+
              "       "+
             "    "+
             "";
         Country country = JaxbUtil.converyToJavaBean(str, Country.class);
         System.out.println(country);
     }

 }

 

输出结果分别为：

    中国
   
       
            江苏省
            南京市
       
       
            浙江省
            杭州市
       
   


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

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