Jaxb annotation初步使用(Object转xml)

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。