Jaxb annotation初步使用
Jaxb annotation初步使用
肥猫钓鱼 发表于3年前
Jaxb annotation初步使用
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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。

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