JAXB注解使用

时间 2019-11-09

标签 jaxb 注解使用繁體版

原文原文链接

一.Jaxb处理java对象和xml之间转换经常使用的annotation有：

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

　二.经常使用annotation使用说明

@XmlType

　　@XmlType用在class类的注解，常与@XmlRootElement，@XmlAccessorType一块儿使用。它有三个属性：name、propOrder、namespace，常用的只有前两个属性。如：html

@XmlType(name = "basicStruct", propOrder = {
    "intValue",
    "stringArray",
    "stringValue"
)

在使用@XmlType的propOrder 属性时，必须列出JavaBean对象中的全部属性，不然会报错。

　　2.@XmlElement

　　@XmlElement将Java对象的属性映射为xml的节点，在使用@XmlElement时，可经过name属性改变java对象属性在xml中显示的名称。如：java

　　@XmlElement(name="Address")　　app

　　private String yourAddress;ide

　　3.@XmlRootElement

　　@XmlRootElement用于类级别的注解，对应xml的跟元素，常与 @XmlType 和 @XmlAccessorType一块儿使用。如：this

　　@XmlType
　　@XmlAccessorType(XmlAccessType.FIELD)
　　@XmlRootElement
　　public class Address {}spa

　　4.@XmlAttribute

　　@XmlAttribute用于把java对象的属性映射为xml的属性,并可经过name属性为生成的xml属性指定别名。如：.net

　　@XmlAttribute(name="Country")
　　private String state;code

　　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一块儿使用。它的属性值是XmlAccessType的4个枚举值，分　　　别为：orm

　　XmlAccessType.FIELD:java对象中的全部成员变量xml

　　XmlAccessType.PROPERTY：java对象中全部经过getter/setter方式访问的成员变量

　　XmlAccessType.PUBLIC_MEMBER：java对象中全部的public访问权限的成员变量和经过getter/setter方式访问的成员变量

　　XmlAccessType.NONE:java对象的全部属性都不映射为xml的元素

　　注意：@XmlAccessorType的默认访问级别是XmlAccessType.PUBLIC_MEMBER，所以，若是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，不然在由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，若是@XmlAccessorType的访问权限　　　为XmlAccessType.NONE，若是在java的成员变量上使用了@XmlElement或@XmlAttribute注解，这些成员变量依然能够映射到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经常使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，须要本身写一个adapter类继承XmlAdapter抽象类，并实现里面的方法。

　　@XmlJavaTypeAdapter(value=xxx.class),value为本身定义的adapter类

　　XmlAdapter以下：

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)，可是生成的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)，因此此处注释掉了@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,可是在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，而且由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做为示例。