Jaxb annotation

一.Jaxb处理java对象和xml之间转换常用的annotation有：

1. @XmlType
2. @XmlElement
3. @XmlRootElement
4. @XmlAttribute
5. @XmlAccessorType
6. @XmlAccessorOrder
7. @XmlTransient
8. @XmlJavaTypeAdapter

　二.常用annotation使用说明

 

1. @XmlType

　　@XmlType用在class类的注解，常与@XmlRootElement，@XmlAccessorType一起使用。它有三个属性：name、propOrder、namespace，经常使用的只有前两个属性。如：

@XmlType(name = "basicStruct", propOrder = {
    "intValue",
    "stringArray",
    "stringValue"
)

在使用@XmlType的propOrder 属性时，必须列出JavaBean对象中的所有属性，否则会报错。

　　2.@XmlElement

　　@XmlElement将java对象的属性映射为xml的节点，在使用@XmlElement时，可通过name属性改变java对象属性在xml中显示的名称。如：

　　@XmlElement(name="Address")　　

　　private String yourAddress;

　　3.@XmlRootElement

　　@XmlRootElement用于类级别的注解，对应xml的跟元素，常与 @XmlType 和 @XmlAccessorType一起使用。如：

　　@XmlType
　　@XmlAccessorType(XmlAccessType.FIELD)
　　@XmlRootElement
　　public class Address {}

　　4.@XmlAttribute

　　@XmlAttribute用于把java对象的属性映射为xml的属性,并可通过name属性为生成的xml属性指定别名。如：

　　@XmlAttribute(name="Country")
　　private String state;

　　5.@XmlAccessorType

　　@XmlAccessorType用于指定由java对象生成xml文件时对java对象属性的访问方式。常与@XmlRootElement、@XmlType一起使用。它的属性值是XmlAccessType的4个枚举值，分　　　别为：

　　XmlAccessType.FIELD:java对象中的所有成员变量

　　XmlAccessType.PROPERTY：java对象中所有通过getter/setter方式访问的成员变量

　　XmlAccessType.PUBLIC_MEMBER：java对象中所有的public访问权限的成员变量和通过getter/setter方式访问的成员变量

　　XmlAccessType.NONE:java对象的所有属性都不映射为xml的元素

　　注意：@XmlAccessorType的默认访问级别是XmlAccessType.PUBLIC_MEMBER，因此，如果java对象中的private成员变量设置了public权限的getter/setter方法，就不要在　　　private变量上使用@XmlElement和@XmlAttribute注解，否则在由java对象生成xml时会报同一个属性在java类里存在两次的错误。同理，如果@XmlAccessorType的访问权限　　　为XmlAccessType.NONE，如果在java的成员变量上使用了@XmlElement或@XmlAttribute注解，这些成员变量依然可以映射到xml文件。

　　6.@XmlAccessorOrder

　　@XmlAccessorOrder用于对java对象生成的xml元素进行排序。它有两个属性值：

　　AccessorOrder.ALPHABETICAL：对生成的xml元素按字母书序排序

　　XmlAccessOrder.UNDEFINED:不排序

　　7.@XmlTransient

　　@XmlTransient用于标示在由java对象映射xml时，忽略此属性。即，在生成的xml文件中不出现此元素。

　　8.@XmlJavaTypeAdapter

　　@XmlJavaTypeAdapter常用在转换比较复杂的对象时，如map类型或者格式化日期等。使用此注解时，需要自己写一个adapter类继承XmlAdapter抽象类，并实现里面的方法。

　　@XmlJavaTypeAdapter(value=xxx.class),value为自己定义的adapter类

　　XmlAdapter如下：

public abstract class XmlAdapter<ValueType,BoundType> {
    // Do-nothing constructor for the derived classes.
    protected XmlAdapter() {}
    // Convert a value type to a bound type.
    public abstract BoundType unmarshal(ValueType v);
    // Convert a bound type to a value type.
    public abstract ValueType marshal(BoundType v);
 }

　三.示例

　　1.Shop.java

package jaxb.shop;

 

import java.util.Set;

 

import javax.xml.bind.annotation.XmlAccessOrder;

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;

import javax.xml.bind.annotation.XmlElementWrapper;

import javax.xml.bind.annotation.XmlAccessorOrder;

 

@XmlAccessorOrder(XmlAccessOrder.ALPHABETICAL)

@XmlAccessorType(XmlAccessType.FIELD)

@XmlType(name = "shop", propOrder = { "name", "number", "describer", "address","orders" })

@XmlRootElement(name = "CHMart")

public class Shop {

 

    @XmlAttribute

    private String name;

 

    // @XmlElement

    private String number;

 

    @XmlElement

    private String describer;

 

    @XmlElementWrapper(name = "orders")

    @XmlElement(name = "order")

    private Set<Order> orders;

 

    @XmlElement

    private Address address;

 

    public Shop() {

    }

 

    public Shop(String name, String number, String describer, Address address) {

        this.name = name;

        this.number = number;

        this.describer = describer;

        this.address = address;

    }

 

    getter/setter略

//同时使用了@XmlType（propOrder={}）和@XmlAccessorOrder(XmlAccessOrder.ALPHABETICAL)，但是生成的xml只按照propOrder定义的顺序生成元素

　　2.Order.java

package jaxb.shop;

 

import java.math.BigDecimal;

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.XmlRootElement;

import javax.xml.bind.annotation.XmlType;

import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;

 

@XmlType(name="order",propOrder={"shopName","orderNumber","price","amount","purDate","customer"})

@XmlAccessorType(XmlAccessType.FIELD)

@XmlRootElement

public class Order {

 

//  @XmlElement　　

    private String shopName;

 

    @XmlAttribute

    private String orderNumber;

 

//  @XmlElement

    @XmlJavaTypeAdapter(value=DateAdapter.class)

    private Date purDate;

 

//  @XmlElement

    private BigDecimal price;

 

//  @XmlElement

    private int amount;

 

//  @XmlElement

    private Customer customer;

 

    public Order() {

    }

 

    public Order(String shopName, String orderNumber, Date purDate,

            BigDecimal price, int amount) {

        this.shopName = shopName;

        this.orderNumber = orderNumber;

        this.purDate = purDate;

        this.price = price;

        this.amount = amount;

    }

getter/setter略

//@XmlAccessorType(XmlAccessType.FIELD)，所以此处注释掉了@XmlElement，xml中依然会生成这些元素

　　3.Customer.java

package jaxb.shop;

 

import java.util.Set;

import javax.xml.bind.annotation.XmlType;

import javax.xml.bind.annotation.XmlAttribute;

import javax.xml.bind.annotation.XmlElement;

import javax.xml.bind.annotation.XmlRootElement;

import javax.xml.bind.annotation.XmlAccessType;

import javax.xml.bind.annotation.XmlAccessorType;

 

@XmlType

@XmlAccessorType(XmlAccessType.FIELD)

@XmlRootElement

public class Customer {

 

    @XmlAttribute

    private String name;

 

    private String gender;

 

    private String phoneNo;

 

    private Address address;

 

    private Set<Order> orders;

 

    public Customer() {

    }

 

    public Customer(String name, String gender, String phoneNo, Address address) {

        this.name = name;

        this.gender = gender;

        this.phoneNo = phoneNo;

        this.address = address;

    }

getter/setter略

　　4.Address.java

package jaxb.shop;

 

import javax.xml.bind.annotation.XmlAttribute;

import javax.xml.bind.annotation.XmlType;

import javax.xml.bind.annotation.XmlElement;

import javax.xml.bind.annotation.XmlRootElement;

import javax.xml.bind.annotation.XmlAccessType;

import javax.xml.bind.annotation.XmlAccessorType;

import javax.xml.bind.annotation.XmlAccessOrder;

import javax.xml.bind.annotation.XmlAccessorOrder;

 

@XmlType(propOrder={"state","province","city","street","zip"})

@XmlAccessorOrder(XmlAccessOrder.ALPHABETICAL)

@XmlAccessorType(XmlAccessType.NONE)

@XmlRootElement

public class Address {

 

    @XmlAttribute　

    private String state;

     

    @XmlElement

    private String province;

     

    @XmlElement

    private String city;

 

    @XmlElement

    private String street;

     

    @XmlElement

    private String zip;

 

    public Address() {

        super();

    }

 

    public Address(String state, String province, String city, String street,

            String zip) {

        super();

        this.state = state;

        this.province = province;

        this.city = city;

        this.street = street;

        this.zip = zip;

    }

getter/setter略

//注意：虽然@XmlAccessorType为XmlAccessType.NONE,但是在java类的私有属性上加了@XmlAttribute和@XmlElement注解后，这些私有成员会映射生成xml的元素

　　5.DateAdapter.java

package jaxb.shop;

 

import java.util.Date;

import java.text.SimpleDateFormat;

 

import javax.xml.bind.annotation.adapters.XmlAdapter;

 

public class DateAdapter extends XmlAdapter<String, Date> {

 

    private String pattern = "yyyy-MM-dd HH:mm:ss";

    SimpleDateFormat fmt = new SimpleDateFormat(pattern);

     

    @Override

    public Date unmarshal(String dateStr) throws Exception {

         

        return fmt.parse(dateStr);

    }

 

    @Override

    public String marshal(Date date) throws Exception {

         

        return fmt.format(date);

    }

 

}

//用于格式化日期在xml中的显示格式，并且由xml unmarshal为java对象时，将字符串解析为Date对象

　　6.ShopTest.java

package jaxb.shop;

 

import java.io.FileReader;

import java.io.FileWriter;

import java.io.IOException;

import java.math.BigDecimal;

import java.util.Date;

import java.util.HashSet;

import java.util.Set;

 

import javax.xml.bind.JAXBContext;

import javax.xml.bind.JAXBException;

import javax.xml.bind.Marshaller;

import javax.xml.bind.Unmarshaller;

 

public class ShopTest {

 

    public static void main(String[] args) throws JAXBException, IOException{

        Set<Order> orders = new HashSet<Order>();

         

        Address address1 = new Address("China", "ShangHai", "ShangHai", "Huang", "200000");

        Customer customer1 = new Customer("Jim", "male", "13699990000", address1);

        Order order1 = new Order("Mart", "LH59900", new Date(), new BigDecimal(60), 1);

        order1.setCustomer(customer1);

         

        Address address2 = new Address("China", "JiangSu", "NanJing", "ZhongYangLu", "210000");

        Customer customer2 = new Customer("David", "male", "13699991000", address2);

        Order order2 = new Order("Mart", "LH59800", new Date(), new BigDecimal(80), 1);

        order2.setCustomer(customer2);

         

        orders.add(order1);

        orders.add(order2);

         

        Address address3 = new Address("China", "ZheJiang", "HangZhou", "XiHuRoad", "310000");

        Shop shop = new Shop("CHMart", "100000", "EveryThing",address3);

        shop.setOrder(orders);

         

         

        FileWriter writer = null;

        JAXBContext context = JAXBContext.newInstance(Shop.class);

        try {

            Marshaller marshal = context.createMarshaller();

            marshal.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);

            marshal.marshal(shop, System.out);

             

            writer = new FileWriter("shop.xml");

            marshal.marshal(shop, writer);

        } catch (Exception e) {

            e.printStackTrace();

        }

         

        Unmarshaller unmarshal = context.createUnmarshaller();

        FileReader reader = new FileReader("shop.xml") ;

        Shop shop1 = (Shop)unmarshal.unmarshal(reader);

         

        Set<Order> orders1 = shop1.getOrder();

        for(Order order : orders1){

            System.out.println("***************************");

            System.out.println(order.getOrderNumber());

            System.out.println(order.getCustomer().getName());

            System.out.println("***************************");

        }

    }

}

　　7.生成的xml文件

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

<CHMart name="CHMart">

    <number>100000</number>

    <describer>EveryThing</describer>

    <address state="China">

        <province>ZheJiang</province>

        <city>HangZhou</city>

        <street>XiHuRoad</street>

        <zip>310000</zip>

    </address>

    <orders>

        <order orderNumber="LH59800">

            <shopName>Mart</shopName>

            <price>80</price>

            <amount>1</amount>

            <purDate>2012-03-25 12:57:23</purDate>

            <customer name="David">

                <gender>male</gender>

                <phoneNo>13699991000</phoneNo>

                <address state="China">

                    <province>JiangSu</province>

                    <city>NanJing</city>

                    <street>ZhongYangLu</street>

                    <zip>210000</zip>

                </address>

            </customer>

        </order>

        <order orderNumber="LH59900">

            <shopName>Mart</shopName>

            <price>60</price>

            <amount>1</amount>

            <purDate>2012-03-25 12:57:23</purDate>

            <customer name="Jim">

                <gender>male</gender>

                <phoneNo>13699990000</phoneNo>

                <address state="China">

                    <province>ShangHai</province>

                    <city>ShangHai</city>

                    <street>Huang</street>

                    <zip>200000</zip>

                </address>

            </customer>

        </order>

    </orders>

</CHMart>

　　以上是以一个简单的商店订单模型作为示例。