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:
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:
@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement
public class Address {}
4.@XmlAttribute
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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