一.Jaxb處理java對象和xml之間轉換常用的annotation有:
- @XmlType
- @XmlElement
- @XmlRootElement
- @XmlAttribute
- @XmlAccessorType
- @XmlAccessorOrder
- @XmlTransient
- @XmlJavaTypeAdapter
二.常用annotation使用說明
-
@XmlType
@XmlType用在class類的註解,常與@XmlRootElement,@XmlAccessorType一起使用。它有三個屬性:name、propOrder、namespace,經常使用的只有前兩個屬性。如:
@XmlType(name = "basicStruct", propOrder = { "intValue", "stringArray", "stringValue" )
在使用@XmlType的propOrder 屬性時,必須列出JavaBean對象中的所有屬性,否則會報錯。
2.@XmlElement
@XmlElement將java對象的屬性映射爲xml的節點,在使用@XmlElement時,可通過name屬性改變java對象屬性在xml中顯示的名稱。如:
如果 required爲 true,則將 Javabean 屬性映射到一個 minOccurs="1" 的 XML 模式元素聲明。maxOccurs 爲 "1" 表示單個賦值的屬性,maxOccurs 爲 "unbounded" 則表示多個賦值的屬性。
如果 required爲 false,則將 Javabean 屬性映射到一個 minOccurs="0" 的 XML 模式元素聲明。maxOccurs 爲 "1" 表示單個賦值的屬性,maxOccurs 爲 "unbounded" 則表示多個賦值的屬性。
3.@XmlRootElement
@XmlRootElement用於類級別的註解,對應xml的跟元素,常與 @XmlType 和 @XmlAccessorType一起使用。如:
@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement
public class Address {}
4.@XmlAttribute
private String state;
5.@XmlAccessorType
@XmlAccessorType用於指定由java對象生成xml文件時對java對象屬性的訪問方式。常與@XmlRootElement、@XmlType一起使用。它的屬性值是XmlAccessType的4個枚舉值,分 別爲:
XmlAccessType.FIELD:java對象中的所有成員變量
XmlAccessType.PROPERTY:java對象中所有通過getter/setter方式訪問的成員變量
XmlAccessType.PUBLIC_MEMBER:java對象中所有的public訪問權限的成員變量和通過getter/setter方式訪問的成員變量
XmlAccessType.NONE:java對象的所有屬性都不映射爲xml的元素
注意:@XmlAccessorType的默認訪問級別是XmlAccessType.PUBLIC_MEMBER,因此,如果java對象中的private成員變量設置了public權限的getter/setter方法,就不要在 private變量上使用@XmlElement和@XmlAttribute註解,否則在由java對象生成xml時會報同一個屬性在java類裏存在兩次的錯誤。同理,如果@XmlAccessorType的訪問權限 爲XmlAccessType.NONE,如果在java的成員變量上使用了@XmlElement或@XmlAttribute註解,這些成員變量依然可以映射到xml文件。
6.@XmlAccessorOrder
@XmlAccessorOrder用於對java對象生成的xml元素進行排序。它有兩個屬性值:
AccessorOrder.ALPHABETICAL:對生成的xml元素按字母書序排序
XmlAccessOrder.UNDEFINED:不排序
7.@XmlTransient
@XmlTransient用於標示在由java對象映射xml時,忽略此屬性。即,在生成的xml文件中不出現此元素。
8.@XmlJavaTypeAdapter
@XmlJavaTypeAdapter常用在轉換比較複雜的對象時,如map類型或者格式化日期等。使用此註解時,需要自己寫一個adapter類繼承XmlAdapter抽象類,並實現裏面的方法。
@XmlJavaTypeAdapter(value=xxx.class),value爲自己定義的adapter類
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); }
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
//同時使用了@XmlType(propOrder={})和@XmlAccessorOrder(XmlAccessOrder.ALPHABETICAL),但是生成的xml只按照propOrder定義的順序生成元素
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),所以此處註釋掉了@XmlElement,xml中依然會生成這些元素
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:雖然@XmlAccessorType爲XmlAccessType.NONE,但是在java類的私有屬性上加了@XmlAttribute和@XmlElement註解後,這些私有成員會映射生成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);
}
}
//用於格式化日期在xml中的顯示格式,並且由xml unmarshal爲java對象時,將字符串解析爲Date對象
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>