JAXB注解使用 一.Jaxb处理java对象和xml之间转换常用的annotation有:  二.常用annotation使用说明  三.示例

  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
    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
//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  
    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
//@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
    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

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 
    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
//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 extendsXmlAdapter<String, Date> {
 
    privateString pattern = "yyyy-MM-dd HH:mm:ss";
    SimpleDateFormat fmt =new SimpleDateFormat(pattern);
     
    @Override
    publicDate unmarshal(String dateStr) throwsException {
         
        returnfmt.parse(dateStr);
    }
 
    @Override
    publicString marshal(Date date) throwsException {
         
        returnfmt.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 {
 
    publicstatic 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(), newBigDecimal(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(), newBigDecimal(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>2012-03-2512:57:23</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>2012-03-2512:57:23</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。