JAXB解析xml转换成类的实现方式

<dependency>
    <groupId>javax.xml.bind</groupId>
    <artifactId>jaxb-api</artifactId>
    <version>2.3.1</version>
</dependency>
<dependency>
    <groupId>org.glassfish.jaxb</groupId>
    <artifactId>jaxb-runtime</artifactId>
    <version>2.3.1</version>
</dependency>

@XmlRootElement
      class Point {
         int x;
         int y;
         Point(int _x,int _y) {x=_x;y=_y;}
      }
  
//Example: Code fragment corresponding to XML output
marshal( new Point(3,5), System.out);
 <!-- Example: XML output -->  
 <point>    
    <x> 3 </x>
    <y> 5 </y>
</point>


//注释在模式中生成全局元素声明。全局元素声明与类映射到的XML模式类型相关联。

<!-- Example: XML schema definition -->
<xs:element name="point" type="point"/>
<xs:complexType name="point">
       <xs:sequence>
                        <xs:element name="x" type="xs:int"/>
                        <xs:element name="y" type="xs:int"/>
       </xs:sequence>
</xs:complexType>

@XmlRootElement(name="PriceElement")
public class USPrice {
    @XmlElement
    public java.math.BigDecimal price;
}


Example: XML schema definition -->   
 <xs:element name="PriceElement" type="USPrice"/>   
<xs:complexType name="USPrice">     
    <xs:sequence>       
    <xs:element name="price" type="xs:decimal"/>     
    </sequence>
</xs:complexType>

public class USPrice {
  @XmlElement(name="itemprice")
  public java.math.BigDecimal price;
}

<!-- Example: Local XML Schema element -->   
<xs:complexType name="USPrice"/>     
  <xs:sequence>       
    <xs:element name="itemprice" type="xs:decimal" minOccurs="0"/>     
  </sequence>   
</xs:complexType>

public class USPrice {
    @XmlElement(nillable=true)
    public java.math.BigDecimal price;
}

<!-- Example: Local XML Schema element -->   
<xs:complexType name="USPrice">     
    <xs:sequence>       
        <xs:element name="price" type="xs:decimal" nillable="true" minOccurs="0"/>     
    </sequence>   
</xs:complexType>

public class USPrice {
    @XmlElement(nillable=true, required=true)
    public java.math.BigDecimal price;
}

<!-- Example: Local XML Schema element -->   
<xs:complexType name="USPrice">     
    <xs:sequence>       
        <xs:element name="price" type="xs:decimal" nillable="true" minOccurs="1"/>     
    </sequence>   
</xs:complexType>

public class Foo {
     XmlElements(
         XmlElement(name="A", type=Integer.class),
         XmlElement(name="B", type=Float.class)
      )
      public List items;
 }

// items = [1,2.5]时，得到的xml为
 <A> 1 </A>
 <B> 2.5 </B>
 ...

 <!-- XML Schema fragment -->
 <xs:complexType name="Foo">
   <xs:sequence>
     <xs:choice minOccurs="0" maxOccurs="unbounded">
       <xs:element name="A" type="xs:int"/>
       <xs:element name="B" type="xs:float"/>
     <xs:choice>
   </xs:sequence>
 </xs:complexType>

 // Mapped code fragment
  public class Foo {
      XmlElementWrapper(name="bar")
      XmlElements(
          XmlElement(name="A", type=Integer.class),
          XmlElement(name="B", type=Float.class)
      }
      public List items;
  }

映射结果
  <!-- XML Schema fragment -->
  <xs:complexType name="Foo">
    <xs:sequence>
      <xs:element name="bar">
        <xs:complexType>
          <xs:choice minOccurs="0" maxOccurs="unbounded">
            <xs:element name="A" type="xs:int"/>
            <xs:element name="B" type="xs:float"/>
          </xs:choice>
        </xs:complexType>
      </xs:element>
    </xs:sequence>
  </xs:complexType>

class Foo {
   XmlJavaTypeAdapter(QtoPAdapter.class)
   XmlElements({
       XmlElement(name="A",type=PX.class),
       XmlElement(name="B",type=PY.class)
   })
   Q bar;
}

XmlType abstract class P {...}
XmlType(name="PX") class PX extends P {...}
XmlType(name="PY") class PY extends P {...}

<!-- XML Schema fragment -->
<xs:complexType name="Foo">
  <xs:sequence>
    <xs:element name="bar">
      <xs:complexType>
        <xs:choice minOccurs="0" maxOccurs="unbounded">
          <xs:element name="A" type="PX"/>
          <xs:element name="B" type="PY"/>
        </xs:choice>
      </xs:complexType>
    </xs:element>
  </xs:sequence>
</xs:complexType>

 //Example: code fragment    
 int[] names;    
 
 // XML Serialization Form 1 (Unwrapped collection)  
 <names> ... </names>  
 <names> ... </names>    
 
 // XML Serialization Form 2 ( Wrapped collection )  
 <wrapperElement>     
    <names> value-of-item </names>     
    <names> value-of-item </names>     
    ....  
</wrapperElement>

@XmlRootElement
  class Foo {
      @XmlElement
      @XmlList
      List<String> data;
  }
  
the above code will produce XML like this:
 <foo>  

         <data>abc def</data>

 </foo>

<person>
    <id>111111</id>
    <name>lijie</name>
    <address>
        <province></province>
        <city></city>
        <detail></detail>
    </address>
    <attr property="1231321" />
    <items>
        <item>afgafdafd</item>
        <item>adfadfadfa</item>
    </items>
</person>

@XmlRootElement(name = "person")
public class Person{
    
    @XmlElement(name = "id")
    String id;

    @XmlElement(name = "name")
    String name;

    @XmlElement(name = "address")
    Address addrss;

    @XmlElement(name = "attr")
    Attributes attributes;
    
    @XmlElementWrapper(name =  "items")
    @XmlElement(name = "item")
    List<Item> items;
}

public class Address{
    
    @XmlElement(name = "province")
    String province;

    @XmlElement(name = "city")
    String city;
}

public class Item{
    
    @XmlElement(name = "item")
    String des;
}


public class Attributes{
    
    @XmlAttribute(name = "property")
    String des;
}

ClassPathResource resource = new ClassPathResource("xml/SnmpTrapHitRules.xml");
BufferedReader reader = new BufferedReader(new InputStreamReader(resource.getStream()));

JAXBContext jaxbContext = JAXBContext.newInstance(SnmpTrapHitRuleDto.class);
Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();
snmpTrapHitRuleDto = (SnmpTrapHitRuleDto) unmarshaller.unmarshal(reader);

 // 创建Person对象
Person person = new Person("张三", 30);

// 创建JAXBContext对象
JAXBContext jaxbContext = JAXBContext.newInstance(Person.class);

// 创建Marshaller对象
Marshaller marshaller = jaxbContext.createMarshaller();

// 设置格式化输出
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);

// 将Java对象转换为XML字符串
StringWriter stringWriter = new StringWriter();
marshaller.marshal(person, stringWriter);