JAXB注解使用[转]

一.Jaxb处理java对象和xml之间转换常用的annotation有：

@XmlType
@XmlElement
@XmlRootElement
@XmlAttribute
@XmlAccessorType
@XmlAccessorOrder
@XmlTransient
@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

 1 import java.util.Set;
 2  
 3 import javax.xml.bind.annotation.XmlAccessOrder;
 4 import javax.xml.bind.annotation.XmlAccessType;
 5 import javax.xml.bind.annotation.XmlAccessorType;
 6 import javax.xml.bind.annotation.XmlAttribute;
 7 import javax.xml.bind.annotation.XmlElement;
 8 import javax.xml.bind.annotation.XmlRootElement;
 9 import javax.xml.bind.annotation.XmlType;
10 import javax.xml.bind.annotation.XmlElementWrapper;
11 import javax.xml.bind.annotation.XmlAccessorOrder;
12  
13 @XmlAccessorOrder(XmlAccessOrder.ALPHABETICAL)
14 @XmlAccessorType(XmlAccessType.FIELD)
15 @XmlType(name ="shop", propOrder = {"name", "number","describer", "address","orders"})
16 @XmlRootElement(name ="CHMart")
17 public class Shop {
18  
19     @XmlAttribute
20     privateString name;
21  
22     // @XmlElement
23     privateString number;
24  
25     @XmlElement
26     privateString describer;
27  
28     @XmlElementWrapper(name ="orders")
29     @XmlElement(name ="order")
30     privateSet<Order> orders;
31  
32     @XmlElement
33     privateAddress address;
34  
35     publicShop() {
36     }
37  
38     publicShop(String name, String number, String describer, Address address) {
39         this.name = name;
40         this.number = number;
41         this.describer = describer;
42         this.address = address;
43     }
44  
45     getter/setter略
46 }

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

 1 import java.math.BigDecimal;
 2 import java.util.Date;
 3  
 4 import javax.xml.bind.annotation.XmlAccessType;
 5 import javax.xml.bind.annotation.XmlAccessorType;
 6 import javax.xml.bind.annotation.XmlAttribute;
 7 import javax.xml.bind.annotation.XmlRootElement;
 8 import javax.xml.bind.annotation.XmlType;
 9 import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
10  
11 @XmlType(name="order",propOrder={"shopName","orderNumber","price","amount","purDate","customer"})
12 @XmlAccessorType(XmlAccessType.FIELD)
13 @XmlRootElement
14 public class Order {
15  
16 //  @XmlElement　　
17     privateString shopName;
18  
19     @XmlAttribute
20     privateString orderNumber;
21  
22 //  @XmlElement
23     @XmlJavaTypeAdapter(value=DateAdapter.class)
24     privateDate purDate;
25  
26 //  @XmlElement
27     privateBigDecimal price;
28  
29 //  @XmlElement
30     privateint amount;
31  
32 //  @XmlElement
33     privateCustomer customer;
34  
35     publicOrder() {
36     }
37  
38     publicOrder(String shopName, String orderNumber, Date purDate,
39             BigDecimal price,int amount) {
40         this.shopName = shopName;
41         this.orderNumber = orderNumber;
42         this.purDate = purDate;
43         this.price = price;
44         this.amount = amount;
45     }
46 
47     getter/setter略
48 }

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

 1 import java.util.Set;
 2 import javax.xml.bind.annotation.XmlType;
 3 import javax.xml.bind.annotation.XmlAttribute;
 4 import javax.xml.bind.annotation.XmlElement;
 5 import javax.xml.bind.annotation.XmlRootElement;
 6 import javax.xml.bind.annotation.XmlAccessType;
 7 import javax.xml.bind.annotation.XmlAccessorType;
 8  
 9 @XmlType
10 @XmlAccessorType(XmlAccessType.FIELD)
11 @XmlRootElement
12 public class Customer {
13  
14     @XmlAttribute
15     privateString name;
16  
17     privateString gender;
18  
19     privateString phoneNo;
20  
21     privateAddress address;
22  
23     privateSet<Order> orders;
24  
25     publicCustomer() {
26     }
27  
28     publicCustomer(String name, String gender, String phoneNo, Address address) {
29         this.name = name;
30         this.gender = gender;
31         this.phoneNo = phoneNo;
32         this.address = address;
33     }
34 
35     getter/setter略
36 }

　　4.Address.java

 1 import javax.xml.bind.annotation.XmlAttribute;
 2 import javax.xml.bind.annotation.XmlType;
 3 import javax.xml.bind.annotation.XmlElement;
 4 import javax.xml.bind.annotation.XmlRootElement;
 5 import javax.xml.bind.annotation.XmlAccessType;
 6 import javax.xml.bind.annotation.XmlAccessorType;
 7 import javax.xml.bind.annotation.XmlAccessOrder;
 8 import javax.xml.bind.annotation.XmlAccessorOrder;
 9  
10 @XmlType(propOrder={"state","province","city","street","zip"})
11 @XmlAccessorOrder(XmlAccessOrder.ALPHABETICAL)
12 @XmlAccessorType(XmlAccessType.NONE)
13 @XmlRootElement
14 public class Address {
15  
16     @XmlAttribute　
17     privateString state;
18      
19     @XmlElement
20     privateString province;
21      
22     @XmlElement
23     privateString city;
24  
25     @XmlElement
26     privateString street;
27      
28     @XmlElement
29     privateString zip;
30  
31     publicAddress() {
32         super();
33     }
34  
35     publicAddress(String state, String province, String city, String street,
36             String zip) {
37         super();
38         this.state = state;
39         this.province = province;
40         this.city = city;
41         this.street = street;
42         this.zip = zip;
43     }
44 
45     getter/setter略
46 }

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

 1 import java.util.Date;
 2 import java.text.SimpleDateFormat;
 3  
 4 import javax.xml.bind.annotation.adapters.XmlAdapter;
 5  
 6 public class DateAdapter extendsXmlAdapter<String, Date> {
 7  
 8     private String pattern = "yyyy-MM-dd HH:mm:ss";
 9     SimpleDateFormat fmt =new SimpleDateFormat(pattern);
10      
11     @Override
12     publicDate unmarshal(String dateStr) throwsException {
13         return fmt.parse(dateStr);
14     }
15  
16     @Override
17     publicString marshal(Date date) throwsException {
18         return fmt.format(date);
19     }
20  
21 }

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

 1 import java.io.FileReader;
 2 import java.io.FileWriter;
 3 import java.io.IOException;
 4 import java.math.BigDecimal;
 5 import java.util.Date;
 6 import java.util.HashSet;
 7 import java.util.Set;
 8  
 9 import javax.xml.bind.JAXBContext;
10 import javax.xml.bind.JAXBException;
11 import javax.xml.bind.Marshaller;
12 import javax.xml.bind.Unmarshaller;
13  
14 public class ShopTest {
15  
16     publicstatic void main(String[] args) throws JAXBException, IOException{
17         Set<Order> orders =new HashSet<Order>();
18          
19         Address address1 =new Address("China","ShangHai", "ShangHai", "Huang","200000");
20         Customer customer1 =new Customer("Jim","male", "13699990000", address1);
21         Order order1 =new Order("Mart","LH59900", new Date(), newBigDecimal(60),1);
22         order1.setCustomer(customer1);
23          
24         Address address2 =new Address("China","JiangSu", "NanJing", "ZhongYangLu","210000");
25         Customer customer2 =new Customer("David","male", "13699991000", address2);
26         Order order2 =new Order("Mart","LH59800", new Date(), newBigDecimal(80),1);
27         order2.setCustomer(customer2);
28          
29         orders.add(order1);
30         orders.add(order2);
31          
32         Address address3 =new Address("China","ZheJiang", "HangZhou", "XiHuRoad","310000");
33         Shop shop =new Shop("CHMart","100000", "EveryThing",address3);
34         shop.setOrder(orders);
35          
36          
37         FileWriter writer =null;
38         JAXBContext context = JAXBContext.newInstance(Shop.class);
39         try{
40             Marshaller marshal = context.createMarshaller();
41             marshal.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT,true);
42             marshal.marshal(shop, System.out);
43              
44             writer =new FileWriter("shop.xml");
45             marshal.marshal(shop, writer);
46         }catch (Exception e) {
47             e.printStackTrace();
48         }
49          
50         Unmarshaller unmarshal = context.createUnmarshaller();
51         FileReader reader =new FileReader("shop.xml") ;
52         Shop shop1 = (Shop)unmarshal.unmarshal(reader);
53          
54         Set<Order> orders1 = shop1.getOrder();
55         for(Order order : orders1){
56             System.out.println("***************************");
57             System.out.println(order.getOrderNumber());
58             System.out.println(order.getCustomer().getName());
59             System.out.println("***************************");
60         }
61     }
62 }

　　7.生成的xml文件

 1 <?xml version="1.0"encoding="UTF-8"standalone="yes"?>
 2 <CHMart name="CHMart">
 3     <number>100000</number>
 4     <describer>EveryThing</describer>
 5     <address state="China">
 6         <province>ZheJiang</province>
 7         <city>HangZhou</city>
 8         <street>XiHuRoad</street>
 9         <zip>310000</zip>
10     </address>
11     <orders>
12         <order orderNumber="LH59800">
13             <shopName>Mart</shopName>
14             <price>80</price>
15             <amount>1</amount>
16             <purDate>2012-03-2512:57:23</purDate>
17             <customer name="David">
18                 <gender>male</gender>
19                 <phoneNo>13699991000</phoneNo>
20                 <address state="China">
21                     <province>JiangSu</province>
22                     <city>NanJing</city>
23                     <street>ZhongYangLu</street>
24                     <zip>210000</zip>
25                 </address>
26             </customer>
27         </order>
28         <order orderNumber="LH59900">
29             <shopName>Mart</shopName>
30             <price>60</price>
31             <amount>1</amount>
32             <purDate>2012-03-2512:57:23</purDate>
33             <customer name="Jim">
34                 <gender>male</gender>
35                 <phoneNo>13699990000</phoneNo>
36                 <address state="China">
37                     <province>ShangHai</province>
38                     <city>ShangHai</city>
39                     <street>Huang</street>
40                     <zip>200000</zip>
41                 </address>
42             </customer>
43         </order>
44     </orders>
45 </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