Jaxb处理java对象和xml之间转换常用的annotation

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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)@XmlRootElementpublic 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     @XmlAttribute20     privateString name;21  22     // @XmlElement23     privateString number;24  25     @XmlElement26     privateString describer;27  28     @XmlElementWrapper(name ="orders")29     @XmlElement(name ="order")30     privateSet<Order> orders;31  32     @XmlElement33     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 @XmlRootElement14 public class Order {15  16 //  @XmlElement　　17     privateString shopName;18  19     @XmlAttribute20     privateString orderNumber;21  22 //  @XmlElement23     @XmlJavaTypeAdapter(value=DateAdapter.class)24     privateDate purDate;25  26 //  @XmlElement27     privateBigDecimal price;28  29 //  @XmlElement30     privateint amount;31  32 //  @XmlElement33     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 @XmlType10 @XmlAccessorType(XmlAccessType.FIELD)11 @XmlRootElement12 public class Customer {13  14     @XmlAttribute15     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 @XmlRootElement14 public class Address {15  16     @XmlAttribute　17     privateString state;18      19     @XmlElement20     privateString province;21      22     @XmlElement23     privateString city;24  25     @XmlElement26     privateString street;27      28     @XmlElement29     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     @Override12     publicDate unmarshal(String dateStr) throwsException {13         return fmt.parse(dateStr);14     }15  16     @Override17     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>

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