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：
@XmlElement(name="Address")
private String yourAddress;
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：
@XmlType
@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement
public class Address {}
@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement
public class Address {}
4.@XmlAttribute
@XmlAttribute用於把java對象的屬性映射爲xml的屬性,並可通過name屬性爲生成的xml屬性指定別名。如：
@XmlAttribute(name="Country")
private String state;
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);
}
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)@XmlRootElementpublic 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)@XmlRootElementpublic 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)@XmlRootElementpublic 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：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 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 { 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> |
以上是以一個簡單的商店訂單模型作爲示例。