Question

我有一个相当大的对象树，我想导出到XML。在几个地方使用名为Person的对象（作为userCreated，许多子实体的userModified，作为客户端等）

根据Person对象的使用，我需要在xml中使用不同的元素。例如：

<policy>
  <userCreated>
    <firstName>John</firstName>
    <lastName>Doe</lastName>
  </userCreated>
  <client>
    <clientId>1234</clientId>
    <email>jdoe@example.com</email>
    <firstName>John</firstName>
    <lastName>Doe</lastName>
  </client>
</policy>

userCreated和client是同一对象（名为Person）的实例

如何在bindings.xml中设置？

Answer 1

您可以使用EclipseLink JAXB (MOXy)的@XmlNamedObjectGraph扩展程序来支持此用例。 @XmlNamedObjectGraph允许您执行的操作是为您的数据创建多个视图。

<强>人

下面我们将使用@XmlNamedObjectGraph在Person类上创建一个仅显示2个字段（firstName和lastName）的视图。

import javax.xml.bind.annotation.*;
import org.eclipse.persistence.oxm.annotations.*;

@XmlNamedObjectGraph(
    name = "simple", 
    attributeNodes = {
        @XmlNamedAttributeNode("firstName"), 
        @XmlNamedAttributeNode("lastName")
     }
)
@XmlAccessorType(XmlAccessType.FIELD)
public class Person {

    private int clientId;
    private String firstName;
    private String lastName;
    private String email;

    public void setClientId(int clientId) {
        this.clientId = clientId;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public void setEmail(String email) {
        this.email = email;
    }

}

<强>政策

我们还会在@XmlNamedObjectGraph课程中使用Policy。它表示对userCreated字段应用我们在simple类上定义的名为Person的命名对象图。

import javax.xml.bind.annotation.*;
import org.eclipse.persistence.oxm.annotations.*;

@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
@XmlNamedObjectGraph(
    name = "policy", 
    attributeNodes = {
        @XmlNamedAttributeNode(value = "userCreated", subgraph = "simple"),
        @XmlNamedAttributeNode("client") 
    }
)
public class Policy {

    private Person userCreated;
    private Person client;

    public void setUserCreated(Person userCreated) {
        this.userCreated = userCreated;
    }

    public void setClient(Person client) {
        this.client = client;
    }

}

<强>演示

在下面的演示代码中，我们将使用Marshaller属性指定要在MarshallerProperties.OBJECT_GRAPH上应用的命名对象图。

import javax.xml.bind.*;
import org.eclipse.persistence.jaxb.MarshallerProperties;

public class Demo {

    public static void main(String[] args) throws Exception {
        JAXBContext jc = JAXBContext.newInstance(Policy.class);

        Person person = new Person();
        person.setClientId(1234);
        person.setFirstName("John");
        person.setLastName("Doe");
        person.setEmail("jdoe@example.com");

        Policy policy = new Policy();
        policy.setClient(person);
        policy.setUserCreated(person);

        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        marshaller.setProperty(MarshallerProperties.OBJECT_GRAPH, "policy");
        marshaller.marshal(policy, System.out);
    }

}

<强>输出

以下是运行演示代码的输出：

<?xml version="1.0" encoding="UTF-8"?>
<policy>
   <userCreated>
      <firstName>John</firstName>
      <lastName>Doe</lastName>
   </userCreated>
   <client>
      <clientId>1234</clientId>
      <firstName>John</firstName>
      <lastName>Doe</lastName>
      <email>jdoe@example.com</email>
   </client>
</policy>

了解更多信息

JAXB / MOXy对几个属性使用相同的Entity类型

1 个答案: