JAXB Annotation初步使用
JAXB（Java Architecture for XML Binding簡稱JAXB）容許Java開發人員將Java類映射爲XML表示方式。JAXB提供兩種主要特性：將一個Java對象序列化爲XML，以及反向操做，將XML解析成Java對象。換句話說，JAXB容許以XML格式存儲和讀取數據，而不須要程序的類結構實現特定的讀取XML和保存XML的代碼。java
一.Jaxb經常使用annotation
@XmlTypeapp
@XmlElementide
@XmlRootElement測試
@XmlAttributethis
@XmlAccessorTypespa
@XmlAccessorOrdercode
@XmlTransientorm
@XmlJavaTypeAdapterxml
二.經常使用annotation使用說明
1.@XmlType
@XmlType用在class類的註解，常與@XmlRootElement，@XmlAccessorType一塊兒使用。它有三個屬性：name、propOrder、namespace，常用的只有前兩個屬性。如：對象
@XmlType(name = "basicStruct", propOrder = {
"intValue",
"stringArray",
"stringValue"
)
在使用@XmlType的propOrder 屬性時，必須列出JavaBean對象中的全部屬性，不然會報錯。
2.@XmlElement
@XmlElement將java對象的屬性映射爲xml的節點，在使用@XmlElement時，可經過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一塊兒使用。如：
@XmlType
@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,並可經過name屬性爲生成的xml屬性指定別名。如：
@XmlAttribute(name="Country")
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一塊兒使用。它的屬性值是XmlAccessType的4個枚舉值，分別爲：
XmlAccessType.FIELD:java對象中的全部成員變量
XmlAccessType.PROPERTY：java對象中全部經過getter/setter方式訪問的成員變量
XmlAccessType.PUBLIC_MEMBER：java對象中全部的public訪問權限的成員變量和經過getter/setter方式訪問的成員變量
XmlAccessType.NONE:java對象的全部屬性都不映射爲xml的元素
注意：@XmlAccessorType的默認訪問級別是XmlAccessType.PUBLIC_MEMBER，所以，若是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，不然在由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，若是@XmlAccessorType的訪問權限爲XmlAccessType.NONE，若是在java的成員變量上使用了@XmlElement或@XmlAttribute註解，這些成員變量依然能夠映射到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經常使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，須要本身寫一個adapter類繼承XmlAdapter抽象類，並實現裏面的方法。
@XmlJavaTypeAdapter(value=xxx.class),value爲本身定義的adapter類
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：
Shop.java
package jaxb2;
import javax.xml.bind.annotation.*;
import java.util.Set;
@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;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getNumber() {
return number;
}
public void setNumber(String number) {
this.number = number;
}
public String getDescriber() {
return describer;
}
public void setDescriber(String describer) {
this.describer = describer;
}
public Set<Order> getOrders() {
return orders;
}
public void setOrders(Set<Order> orders) {
this.orders = orders;
}
public Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
}
Order.java
package jaxb2;
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;
}
public String getShopName() {
return shopName;
}
public void setShopName(String shopName) {
this.shopName = shopName;
}
public String getOrderNumber() {
return orderNumber;
}
public void setOrderNumber(String orderNumber) {
this.orderNumber = orderNumber;
}
public Date getPurDate() {
return purDate;
}
public void setPurDate(Date purDate) {
this.purDate = purDate;
}
public BigDecimal getPrice() {
return price;
}
public void setPrice(BigDecimal price) {
this.price = price;
}
public int getAmount() {
return amount;
}
public void setAmount(int amount) {
this.amount = amount;
}
public Customer getCustomer() {
return customer;
}
public void setCustomer(Customer customer) {
this.customer = customer;
}
}
Customer.java
package jaxb2;
import java.util.Set;
import javax.xml.bind.annotation.XmlType;
import javax.xml.bind.annotation.XmlAttribute;
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;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
public String getPhoneNo() {
return phoneNo;
}
public void setPhoneNo(String phoneNo) {
this.phoneNo = phoneNo;
}
public Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
public Set<Order> getOrders() {
return orders;
}
public void setOrders(Set<Order> orders) {
this.orders = orders;
}
}
Address.java
package jaxb2;
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;
}
public String getState() {
return state;
}
public void setState(String state) {
this.state = state;
}
public String getProvince() {
return province;
}
public void setProvince(String province) {
this.province = province;
}
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
public String getStreet() {
return street;
}
public void setStreet(String street) {
this.street = street;
}
public String getZip() {
return zip;
}
public void setZip(String zip) {
this.zip = zip;
}
}
DateAdapter.java
package jaxb2;
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);
}
}
最後作一個測試：
package jaxb2;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;
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;
/**
* Created with IntelliJ IDEA.
* User: ASUS
* Date: 14-7-2
* Time: 下午6:10
* To change this template use File | Settings | File Templates.
*/
public class Test {
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.setOrders(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.getOrders();
for (Order order : orders1) {
System.out.println("***************************");
System.out.println(order.getOrderNumber());
System.out.println(order.getCustomer().getName());
System.out.println("***************************");
}
}
}
以上是以一個簡單的商店訂單模型做爲示例。
====END====
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