JAXB 实现java对象与xml之间互相转换

利用Marshaller和unMarshaller可在java的object对象和xml之间实现转换

首先创建一个简单的Boy对象

[java] view plaincopyprint?

1. @XmlRootElement(name="Root")  
2. @XmlAccessorType(XmlAccessType.PROPERTY)  
3. public class Boy {  
4.       
5.     private String name = "aa";  
6.   
7.     public String getName() {  
8.         return name;  
9.     }  
10.   
11.     public void setName(String name) {  
12.         this.name = name;  
13.     }  
14.       
15. }  

@XmlRootElement(name="Root")@XmlAccessorType(XmlAccessType.PROPERTY)public class Boy {private String name = "aa";public String getName() {return name;}public void setName(String name) {this.name = name;}}

其中@XmlRootElement(name="Root")表明xml的根元素，(name="Root")这个是重新定义xml文件的跟元素，如果没有此name定义，则xml根元素默认跟对象名一致

然后通过Marshaller类实现将对象转换为xml，同时也可利用Unmarshaller类进行xml和类之间的转换

[java] view plaincopyprint?

1. public class JAXBTest {  
2.   
3.     public static void main(String[] args) throws JAXBException {  
4.         JAXBContext context = JAXBContext.newInstance(Boy.class);  
5.           
6.         Marshaller marshaller = context.createMarshaller();  
7.         Unmarshaller unMarshaller = context.createUnmarshaller();  
8.           
9.         System.out.println("----------marshaller--------------");  
10.         Boy boy = new Boy();  
11.         marshaller.marshal(boy, System.out);  
12.           
13.         System.out.println("\n----------unMarshaller--------------");  
14.         //将xml转换为对应的java对象   
15.         String xml = "<Root><name>aa</name></Root>";//此处标签名称须和boy对象的属性一致  
16.         Boy b = (Boy) unMarshaller.unmarshal(new StringReader(xml));  
17.         System.out.println(b.getName());  
18.     }  
19.       
20. }  

public class JAXBTest {public static void main(String[] args) throws JAXBException {JAXBContext context = JAXBContext.newInstance(Boy.class);Marshaller marshaller = context.createMarshaller();Unmarshaller unMarshaller = context.createUnmarshaller();System.out.println("----------marshaller--------------");Boy boy = new Boy();marshaller.marshal(boy, System.out);System.out.println("\n----------unMarshaller--------------");//将xml转换为对应的java对象String xml = "<Root><name>aa</name></Root>";//此处标签名称须和boy对象的属性一致Boy b = (Boy) unMarshaller.unmarshal(new StringReader(xml));System.out.println(b.getName());}}

最后转换打印结果

----------marshaller--------------
<?xml version="1.0" encoding="UTF-8" standalone="yes"?><Root><name>aa</name></Root>
----------unMarshaller--------------
aa

上面介绍的对象boy中只包含简单属性，如果boy中还包含其他对象该做如何处理呢？

[java] view plaincopyprint?

1. @XmlRootElement(name="Root")  
2. @XmlAccessorType(XmlAccessType.PROPERTY)  
3. public class Boy {  
4.       
5.     private String name = "aa";  
6.     private Address address;  
7.       
8.     public String getName() {  
9.         return name;  
10.     }  
11.   
12.     public void setName(String name) {  
13.         this.name = name;  
14.     }  
15.       
16.     @XmlJavaTypeAdapter(AddressAdapter.class)  
17.     public Address getAddress() {  
18.         return address;  
19.     }  
20.       
21.     public void setAddress(Address address) {  
22.         this.address = address;  
23.     }  
24. }  

@XmlRootElement(name="Root")@XmlAccessorType(XmlAccessType.PROPERTY)public class Boy {private String name = "aa";private Address address;public String getName() {return name;}public void setName(String name) {this.name = name;}@XmlJavaTypeAdapter(AddressAdapter.class)public Address getAddress() {return address;}public void setAddress(Address address) {this.address = address;}}

[java] view plaincopyprint?

1. public class Address {  
2.   
3.     private String address;  
4.       
5.     public void setAddress(String address) {  
6.         this.address = address;  
7.     }  
8.   
9.     public String getAddress() {  
10.         return address;  
11.     }  
12.   
13. }  

public class Address {private String address;public void setAddress(String address) {this.address = address;}public String getAddress() {return address;}}

此时的boy对象中包含了Address对象，所以此时boy对象中的getAddress()须设置adapter，

创建AddressAdapter类，继承XmlAdapter<ValueType,BoundType>

[java] view plaincopyprint?

1. public class AddressAdapter extends XmlAdapter<String, Address> {  
2.   
3.     @Override  
4.     public Address unmarshal(String v) throws Exception {  
5.         AddressImpl address = new AddressImpl();  
6.         address.setAddress(v);  
7.         return address;  
8.     }  
9.   
10.     @Override  
11.     public String marshal(Address v) throws Exception {  
12.         return v.getAddress();  
13.     }  
14.   
15. }  

public class AddressAdapter extends XmlAdapter<String, Address> {@Overridepublic Address unmarshal(String v) throws Exception {AddressImpl address = new AddressImpl();address.setAddress(v);return address;}@Overridepublic String marshal(Address v) throws Exception {return v.getAddress();}}

此时即可进行java对象转换为xml

[java] view plaincopyprint?

1. public class JAXBTest {  
2.   
3.     public static void main(String[] args) throws JAXBException {  
4.         JAXBContext context = JAXBContext.newInstance(Boy.class);  
5.           
6.         Marshaller marshaller = context.createMarshaller();  
7.           
8.         System.out.println("----------marshaller--------------");  
9.         Boy boy = new Boy();  
10.         AddressImpl address = new AddressImpl();  
11.         address.setAddress("BeiJing");  
12.         boy.setAddress(address);  
13.         marshaller.marshal(boy, System.out);  
14.           
15.     }  
16.       
17. }  

public class JAXBTest {public static void main(String[] args) throws JAXBException {JAXBContext context = JAXBContext.newInstance(Boy.class);Marshaller marshaller = context.createMarshaller();System.out.println("----------marshaller--------------");Boy boy = new Boy();AddressImpl address = new AddressImpl();address.setAddress("BeiJing");boy.setAddress(address);marshaller.marshal(boy, System.out);}}

最后打印结果为：

<?xml version="1.0" encoding="UTF-8" standalone="yes"?><Root><address>BeiJing</address><name>aa</name></Root>