JAXB注解使用[转]

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

 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
     privateString name;

     // @XmlElement
     privateString number;

     @XmlElement
     privateString describer;

     @XmlElementWrapper(name ="orders")
     @XmlElement(name ="order")
     privateSet<Order> orders;

     @XmlElement
     privateAddress address;

     publicShop() {
     }

     publicShop(String name, String number, String describer, Address address) {
         this.name = name;
         this.number = number;
         this.describer = describer;
         this.address = address;
     }

     getter/setter略
 }

备注：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

　　2.Order.java

 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　　
     privateString shopName;

     @XmlAttribute
     privateString orderNumber;

 //  @XmlElement
     @XmlJavaTypeAdapter(value=DateAdapter.class)
     privateDate purDate;

 //  @XmlElement
     privateBigDecimal price;

 //  @XmlElement
     privateint amount;

 //  @XmlElement
     privateCustomer customer;

     publicOrder() {
     }

     publicOrder(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
 }

备注：@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

 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
     privateString name;

     privateString gender;

     privateString phoneNo;

     privateAddress address;

     privateSet<Order> orders;

     publicCustomer() {
     }

     publicCustomer(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

 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　
     privateString state;

     @XmlElement
     privateString province;

     @XmlElement
     privateString city;

     @XmlElement
     privateString street;

     @XmlElement
     privateString zip;

     publicAddress() {
         super();
     }

     publicAddress(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
 }

备注：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

 import java.util.Date;
 import java.text.SimpleDateFormat;

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

 public class DateAdapter extendsXmlAdapter<String, Date> {

     private String pattern = "yyyy-MM-dd HH:mm:ss";
     SimpleDateFormat fmt =new SimpleDateFormat(pattern);

     @Override
     publicDate unmarshal(String dateStr) throwsException {
         return fmt.parse(dateStr);
     }

     @Override
     publicString marshal(Date date) throwsException {
         return fmt.format(date);
     }

 }

备注：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

 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 {

     publicstatic void main(String[] args) throws JAXBException, IOException{
         Set<Order> orders =new HashSet<Order>();

         Address address1 =new Address("China","ShangHai", "ShangHai", "Huang","");
         Customer customer1 =new Customer("Jim","male", "", address1);
         Order order1 =new Order("Mart","LH59900", new Date(), newBigDecimal(),);
         order1.setCustomer(customer1);

         Address address2 =new Address("China","JiangSu", "NanJing", "ZhongYangLu","");
         Customer customer2 =new Customer("David","male", "", address2);
         Order order2 =new Order("Mart","LH59800", new Date(), newBigDecimal(),);
         order2.setCustomer(customer2);

         orders.add(order1);
         orders.add(order2);

         Address address3 =new Address("China","ZheJiang", "HangZhou", "XiHuRoad","");
         Shop shop =new Shop("CHMart","", "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></number>
     <describer>EveryThing</describer>
     <address state="China">
         <province>ZheJiang</province>
         <city>HangZhou</city>
         <street>XiHuRoad</street>
         <zip></zip>
     </address>
     <orders>
         <order orderNumber="LH59800">
             <shopName>Mart</shopName>
             <price></price>
             <amount></amount>
             <purDate>--::</purDate>
             <customer name="David">
                 <gender>male</gender>
                 <phoneNo></phoneNo>
                 <address state="China">
                     <province>JiangSu</province>
                     <city>NanJing</city>
                     <street>ZhongYangLu</street>
                     <zip></zip>
                 </address>
             </customer>
         </order>
         <order orderNumber="LH59900">
             <shopName>Mart</shopName>
             <price></price>
             <amount></amount>
             <purDate>--::</purDate>
             <customer name="Jim">
                 <gender>male</gender>
                 <phoneNo></phoneNo>
                 <address state="China">
                     <province>ShangHai</province>
                     <city>ShangHai</city>
                     <street>Huang</street>
                     <zip></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。

转自：http://blog.csdn.net/czplplp_900725/article/details/7888896