JAXB教程

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。
JAXB2.0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。

概念

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。

示例

Order.java

package com.ricky.domain;
 
import javax.xml.bind.annotation.*;
import java.util.List;
import java.util.Set;
 
/** * 订单 * * @author Ricky Fung * @create 2016-06-13 18:27 */
@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement
@XmlType(propOrder = {"id","totalPrice","category","shoppingList","tags","address"})
public class Order {
 
    @XmlAttribute(name="id")
    private long id;
    private String category;
 
    @XmlElementWrapper(name = "shopping_list")
    @XmlElement(name = "shopping_item")
    private List<ShoppingItem> shoppingList;
 
    @XmlElementWrapper(name = "tags")
    @XmlElement(name = "tag")
    private Set<String> tags;
 
    @XmlElement(name = "addr",required = true)
    private Address address;
 
    @XmlElement(name = "total_price")
    private float totalPrice;
 
    public long getId() {
        return id;
    }
 
    public void setId(long id) {
        this.id = id;
    }
 
    public String getCategory() {
        return category;
    }
 
    public void setCategory(String category) {
        this.category = category;
    }
 
    public List<ShoppingItem> getShoppingList() {
        return shoppingList;
    }
 
    public void setShoppingList(List<ShoppingItem> shoppingList) {
        this.shoppingList = shoppingList;
    }
 
    public Set<String> getTags() {
        return tags;
    }
 
    public void setTags(Set<String> tags) {
        this.tags = tags;
    }
 
    public Address getAddress() {
        return address;
    }
 
    public void setAddress(Address address) {
        this.address = address;
    }
 
    public float getTotalPrice() {
        return totalPrice;
    }
 
    public void setTotalPrice(float totalPrice) {
        this.totalPrice = totalPrice;
    }
 
    @Override
    public String toString() {
        return "Order{" +
                "id=" + id +
                ",category='" + category + '\'' +
                ",shoppingList=" + shoppingList +
                ",tags=" + tags +
                ",address=" + address +
                ",totalPrice=" + totalPrice +
                '}';
    }
}

ShoppingItem.java

package com.ricky.domain;
 
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
 
/** * 购物项 * * @author Ricky Fung * @create 2016-06-13 19:00 */
@XmlAccessorType(XmlAccessType.FIELD)
public class ShoppingItem {
    private String name;
    private float price;
    private int num;
 
    public String getName() {
        return name;
    }
 
    public void setName(String name) {
        this.name = name;
    }
 
    public float getPrice() {
        return price;
    }
 
    public void setPrice(float price) {
        this.price = price;
    }
 
    public int getNum() {
        return num;
    }
 
    public void setNum(int num) {
        this.num = num;
    }
 
    @Override
    public String toString() {
        return "ShopItem{" +
                "name='" + name + '\'' +
                ",price=" + price +
                ",num=" + num +
                '}';
    }
}

Address.java

package com.ricky.domain;
 
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
 
/** * 收货地址 * * @author Ricky Fung * @create 2016-06-13 18:28 */
@XmlAccessorType(XmlAccessType.FIELD)
public class Address {
    private String province;
    private String city;
    private String district;
    private String street;
 
    public String getProvince() {
        return province;
    }
 
    public void setProvince(String province) {
        this.province = province;
    }
 
    public String getCity() {
        return city;
    }
 
    public void setCity(String city) {
        this.city = city;
    }
 
    public String getDistrict() {
        return district;
    }
 
    public void setDistrict(String district) {
        this.district = district;
    }
 
    public String getStreet() {
        return street;
    }
 
    public void setStreet(String street) {
        this.street = street;
    }
 
    @Override
    public String toString() {
        return "Address{" +
                "province='" + province + '\'' +
                ",city='" + city + '\'' +
                ",district='" + district + '\'' +
                ",street='" + street + '\'' +
                '}';
    }
}

JAXBDemo.java

package com.ricky;
 
import com.ricky.domain.Address;
import com.ricky.domain.Order;
import com.ricky.domain.ShoppingItem;
import com.ricky.util.JAXBUtil;
import javax.xml.bind.JAXBException;
import java.util.*;
 
/** * JAXB示例 * * @author Ricky Fung * @create 2016-06-13 18:15 */
public class JAXBDemo {
 
    public static void main(String[] args) throws JAXBException {
 
        Order order = new Order();
        order.setId(2);
        order.setCategory("3C");
        Set<String> tags = new HashSet<String>();
        tags.add("3C");
        tags.add("手机");
        order.setTags(tags);
 
        List<ShoppingItem> shopping_list = new ArrayList<ShoppingItem>();
        ShoppingItem shoppingItem1 = new ShoppingItem();
        shoppingItem1.setName("Apple 6s Plus 64G");
        shoppingItem1.setPrice(6499f);
        shoppingItem1.setNum(1);
        shopping_list.add(shoppingItem1);
 
        ShoppingItem shoppingItem2 = new ShoppingItem();
        shoppingItem2.setName("魅蓝Note3 32G");
        shoppingItem2.setPrice(999f);
        shoppingItem2.setNum(1);
        shopping_list.add(shoppingItem2);
 
        order.setShoppingList(shopping_list);
 
        order.setTotalPrice(7498f);
 
        Address address = new Address();
        address.setProvince("湖北省");
        address.setCity("武汉市");
        address.setDistrict("武昌区");
        address.setStreet("复兴路");
        order.setAddress(address);
 
        String xml = JAXBUtil.beanToXml(order);
        System.out.println("marshaller order:"+xml);
 
        Order o = JAXBUtil.xmlToBean(xml,Order.class);
        System.out.println("unmarshaller order:"+o);
    }
}

package com.ricky.util;
 
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;
import java.io.StringReader;
import java.io.StringWriter;
 
/** * JAXB工具类 * * @author Ricky Fung * @create 2016-06-13 18:20 */
public class JAXBUtil {
 
    public static String beanToXml(Object obj) throws JAXBException {
 
        JAXBContext jaxbContext = JAXBContext.newInstance(obj.getClass());
        Marshaller marshaller = jaxbContext.createMarshaller();
 
        // 用来指定是否使用换行和缩排对已编组XML数据进行格式化的属性名称
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT,true);
        marshaller.setProperty(Marshaller.JAXB_ENCODING,"UTF-8");
 
        StringWriter writer = new StringWriter();
        marshaller.marshal(obj,writer);
        return writer.toString();
    }
 
    public static <T> T xmlToBean(String xml,Class<T> cls) throws JAXBException {
 
        JAXBContext context = JAXBContext.newInstance(cls);
        Unmarshaller unmarshaller = context.createUnmarshaller();
 
        return (T) unmarshaller.unmarshal(new StringReader(xml));
    }
}

忽略字段

使用@XmlTransient

package com.ricky.domain;
 
import javax.xml.bind.annotation.*;
import java.util.List;
 
/** * ${DESCRIPTION} * * @author Ricky Fung * @create 2016-06-14 18:35 */
@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement
public class Student {
    private long id;
    private String name;
 
    @XmlTransient
    private int age;
 
    @XmlElementWrapper(name = "hobbies")
    @XmlElement(name = "hobby")
    private List<String> hobbies;
 
    public long getId() {
        return id;
    }
 
    public void setId(long 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 List<String> getHobbies() {
        return hobbies;
    }
 
    public void setHobbies(List<String> hobbies) {
        this.hobbies = hobbies;
    }
}

package com.ricky;
 
import com.ricky.domain.Student;
import com.ricky.util.JAXBUtil;
import javax.xml.bind.JAXBException;
import java.util.ArrayList;
import java.util.List;
 
/** * ${DESCRIPTION} * * @author Ricky Fung * @create 2016-06-14 18:34 */
public class JAXBExcludeDemo {
 
    public static void main(String[] args) throws JAXBException {
 
        Student student = new Student();
        student.setId(1l);
        student.setName("Ricky");
        student.setAge(27);
 
        List<String> hobbies = new ArrayList<String>();
        hobbies.add("NBA");
        hobbies.add("电影");
        student.setHobbies(hobbies);
 
        String xml = JAXBUtil.beanToXml(student);
        System.out.println(xml);
    }
}

参考资料：
https://java.net/projects/jaxb2-commons/pages/Home

JAXB教程

简介

概念

示例

忽略字段

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