JAXB注解使用

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发布时间：2019-06-19

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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

@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
    
      {    // 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
    
      orders =new HashSet
     
      ();                 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
      
        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


    
    
         
     
      100000
         
     
      EveryThing
         
             
      
       ZheJiang
              
      
       HangZhou
              
      
       XiHuRoad
              
      
       310000
          
    
     
              
      
                   
       
        Mart
                   
       
        80
                   
       
        1
                   
       
        2012-03-2512:57:23
                   
       
                        
        
         male
                        
        
         13699991000
                        
                            
         
          JiangSu
                             
         
          NanJing
                             
         
          ZhongYangLu
                             
         
          210000
                         
            
               
              
      
                   
       
        Mart
                   
       
        60
                   
       
        1
                   
       
        2012-03-2512:57:23
                   
       
                        
        
         male
                        
        
         13699990000
                        
                            
         
          ShangHai
                             
         
          ShangHai
                             
         
          Huang
                             
         
          200000