Jaxb annotation初步使用

　一.Jaxb處理java對象和xml之間轉換常用的annotation有：

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

　二.常用annotation使用說明

 

1. @XmlType

　　@XmlType用在class類的注解，常與@XmlRootElement，@XmlAccessorType一起使用。它有三個屬性：name、propOrder、namespace，經常使用的只有前兩個屬性。如：

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

在使用@XmlType的propOrder 屬性時，必須列出JavaBean對象中的所有屬性，否則會報錯。

　　2.@XmlElement

　　@XmlElement將java對象的屬性映射為xml的節點，在使用@XmlElement時，可通過name屬性改變java對象屬性在xml中顯示的名稱。如：

　　@XmlElement(name="Address") 　　

　　private String yourAddress;

　　3.@XmlRootElement

　　@XmlRootElement用於類級別的注解，對應xml的跟元素，常與 @XmlType 和 @XmlAccessorType一起使用。如：

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

　　4.@XmlAttribute

　　@XmlAttribute用於把java對象的屬性映射為xml的屬性,並可通過name屬性為生成的xml屬性指定別名。如：

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

　　5.@XmlAccessorType

　　@XmlAccessorType用於指定由java對象生成xml文件時對java對象屬性的訪問方式。常與@XmlRootElement、@XmlType一起使用。它的屬性值是XmlAccessType的4個枚舉值，分　　　別為：

　　XmlAccessType.FIELD:java對象中的所有成員變量

　　XmlAccessType.PROPERTY：java對象中所有通過getter/setter方式訪問的成員變量

　　XmlAccessType.PUBLIC_MEMBER：java對象中所有的public訪問權限的成員變量和通過getter/setter方式訪問的成員變量

　　XmlAccessType.NONE:java對象的所有屬性都不映射為xml的元素

　　注意：@XmlAccessorType的默認訪問級別是XmlAccessType.PUBLIC_MEMBER，因此，如果java對象中的private成員變量設置了public權限的getter/setter方法，就不要在　　　private變量上使用@XmlElement和@XmlAttribute注解，否則在由java對象生成xml時會報同一個屬性在java類里存在兩次的錯誤。同理，如果@XmlAccessorType的訪問權限　　　為XmlAccessType.NONE，如果在java的成員變量上使用了@XmlElement或@XmlAttribute注解，這些成員變量依然可以映射到xml文件。

　　6.@XmlAccessorOrder

　　@XmlAccessorOrder用於對java對象生成的xml元素進行排序。它有兩個屬性值：

　　AccessorOrder.ALPHABETICAL：對生成的xml元素按字母書序排序

　　XmlAccessOrder.UNDEFINED:不排序

　　7.@XmlTransient

　　@XmlTransient用於標示在由java對象映射xml時，忽略此屬性。即，在生成的xml文件中不出現此元素。

　　8.@XmlJavaTypeAdapter

　　@XmlJavaTypeAdapter常用在轉換比較復雜的對象時，如map類型或者格式化日期等。使用此注解時，需要自己寫一個adapter類繼承XmlAdapter抽象類，並實現里面的方法。

　　@XmlJavaTypeAdapter(value=xxx.class),value為自己定義的adapter類

　　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

//同時使用了@XmlType（propOrder={}）和@XmlAccessorOrder(XmlAccessOrder.ALPHABETICAL)，但是生成的xml只按照propOrder定義的順序生成元素

　　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)，所以此處注釋掉了@XmlElement，xml中依然會生成這些元素

　　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：雖然@XmlAccessorType為XmlAccessType.NONE,但是在java類的私有屬性上加了@XmlAttribute和@XmlElement注解后，這些私有成員會映射生成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);
	}

}

//用於格式化日期在xml中的顯示格式，並且由xml unmarshal為java對象時，將字符串解析為Date對象

　　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>

　　以上是以一個簡單的商店訂單模型作為示例。