使用 JAXB 解组

Question

我需要将 XML 字符串解组到项目中已经存在的类中，但我不知道如何将 XML 的某个部分解组为对象列表。让我用一些代码解释一下：

我有这个 XML：

<user>
  <id>123</id>
  <name>John Doe</name>
  <vaddresses>
    <address>
      <street>Street XYZ</street>
    </address>
    <address>
      <street>Street ABC</street>
    </address>
  </vaddresses>
</user>

我有这些课程：

• 用户

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "User", propOrder = {"id", "name", "addresses"})
public class User {

    @XmlElement
    private int id;

    @XmlElement
    private String name;

    @XmlElement
    private List<Address> addresses;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public List<Address> getAddresses() {
        return addresses;
    }

    public void setAddresses(List<Address> addresses) {
        this.addresses = addresses;
    }

• 地址

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "Address", propOrder = {"street"})
public class Address {

    @XmlElement
    private String street;

    public String getStreet() {
        return street;
    }

    public void setStreet(String street) {
        this.street = street;
    }
}

当我尝试将 XML 解组到这些类中时，字段 id 和 name 被正确处理，但 addresses：

• 输出

User: 
    Id: 123
    Nome: John Doe
    Addresses: null

我该如何解决这个问题？是否有一些我可以使用的 JAXB 注释？如何？还是我需要创建某种类型的 XmlAdapter？ （我试过这个但没有成功......）

Answer 1

您可以利用@XmlElementWrapper 在您的集合周围添加分组元素：

@XmlElementWrapper(name="vaddresses")
@XmlElement(name="address")
private List<Address> addresses;

注意

您添加的注释过多。 JAXB 是异常配置，因此您只需要注释您希望 XML 表示与默认值不同的位置。

• http://blog.bdoughan.com/2012/07/jaxb-no-annotations-required.html

Answer 2

我认为您必须更改私有财产地址的类型：

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "User", propOrder = {"id", "name", "vaddresses"})
public class User {

    @XmlElement
    private int id;

    @XmlElement
    private String name;

    @XmlElement
    private VAddress vaddresses;

    //...
 }

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "VAddress", propOrder = {"addresses"})
public class VAddress {

    @XmlElement
    private List<Address> addresses;

    //...
 }

或许你也可以试试@XmlElementWrapper注解。

问候，

Answer 3

用户.java

package generated;

import java.util.ArrayList;
import java.util.List;
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "", propOrder = {
    "id",
    "name",
    "vaddresses"
})
@XmlRootElement(name = "user")
public class User {

    protected int id;
    @XmlElement(required = true)
    protected String name;
    @XmlElement(required = true)
    protected User.Vaddresses vaddresses;

    public int getId() {
        return id;
    }


    public void setId(int value) {
        this.id = value;
    }

    public String getName() {
        return name;
    }


    public void setName(String value) {
        this.name = value;
    }


    public User.Vaddresses getVaddresses() {
        return vaddresses;
    }

    public void setVaddresses(User.Vaddresses value) {
        this.vaddresses = value;
    }


    @XmlAccessorType(XmlAccessType.FIELD)
    @XmlType(name = "", propOrder = {
        "address"
    })
    public static class Vaddresses {

        @XmlElement(required = true)
        protected List<User.Vaddresses.Address> address;

        public List<User.Vaddresses.Address> getAddress() {
            if (address == null) {
                address = new ArrayList<User.Vaddresses.Address>();
            }
            return this.address;
        }


        @XmlAccessorType(XmlAccessType.FIELD)
        @XmlType(name = "", propOrder = {
            "street"
        })
        public static class Address {

            @XmlElement(required = true)
            protected String street;


            public String getStreet() {
                return street;
            }

            public void setStreet(String value) {
                this.street = value;
            }

        }

    }

}

JaxBExample.java

package generated;
import generated.User.Vaddresses.Address;

import java.io.File;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Unmarshaller;

public class JAXBExample {
    public static void main(String[] args) {

     try {

        File file = new File("D:\\StackOverFlow\\JAXBTest\\file.xml");
        JAXBContext jaxbContext = JAXBContext.newInstance(User.class);

        Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();
        User user = (User) jaxbUnmarshaller.unmarshal(file);
        System.out.println("ID::"+user.getId());
        System.out.println("Name::"+user.getName());
        System.out.print("Addresses::");
        for(Address address:user.getVaddresses().getAddress())
        {
            System.out.println(address.getStreet());
        }


      } catch (JAXBException e) {
        e.printStackTrace();
      }

    }
}

输出：--

ID::123 名称::John Doe 地址::Street XYZ 街道ABC