java - JAXB 条件绑定(bind)

Question

我有一个类:

@XmlRootElement 
Class ClassA {

public long objectId;

public String status;

public String property1;

......
}

我希望 JAXB 的 JSON 输出以属性“status”为条件。例如:

if status != "deleted"-> 绑定(bind)所有字段

{"objectId":1,"status":"new","property1":"value1","property2":"value2","prop3":"val3"....}

if status == "deleted"-> 只绑定(bind) 2 个字段

{"objectsId":1,"status":"deleted"}

这可能与 JAXB 相关吗？？？ 谢谢

Answer 1

注意:我是 EclipseLink JAXB (MOXy) JAXB (JSR-222) 的领导和成员专家组。

您可以使用我们在 EclipseLink 2.5 中添加到 MOXy 的对象图扩展来处理此用例。您可以从以下位置下载夜间构建:

• http://www.eclipse.org/eclipselink/downloads/nightly.php

A 级

我们将使用 MOXy 的对象图扩展来指定可以编码的值的子集。

• http://blog.bdoughan.com/2013/03/moxys-object-graphs-inputoutput-partial.html
• http://blog.bdoughan.com/2013/03/moxys-object-graphs-partial-models-on.html

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

@XmlRootElement 
@XmlNamedObjectGraph(
    name="deleted",
    attributeNodes = { 
        @XmlNamedAttributeNode("objectId"),
        @XmlNamedAttributeNode("status")
    }
)
public class ClassA {

    public long objectId;
    public String status;
    public String property1;

}

jaxb.properties

要将 MOXy 指定为您的 JAXB 提供程序，您需要包含一个名为 jaxb.properties 的文件在与域模型相同的包中，包含以下条目(请参阅:http://blog.bdoughan.com/2011/05/specifying-eclipselink-moxy-as-your.html):

javax.xml.bind.context.factory=org.eclipse.persistence.jaxb.JAXBContextFactory

演示

在下面的演示代码中，我们将设置 MarshallerProperties.OBJECT_GRAPH属性(property)deleted在 Marshaller 上如果status在 ClassA 的实例上等于deleted .

import java.util.*;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.Marshaller;
import org.eclipse.persistence.jaxb.JAXBContextProperties;
import org.eclipse.persistence.jaxb.MarshallerProperties;

public class Demo {

    public static void main(String[] args) throws Exception {
        Map<String, Object> properties = new HashMap<String, Object>(2);
        properties.put(JAXBContextProperties.MEDIA_TYPE, "application/json");
        properties.put(JAXBContextProperties.JSON_INCLUDE_ROOT, false);
        JAXBContext jc = JAXBContext.newInstance(new Class[] {ClassA.class}, properties);

        ClassA classA = new ClassA();
        classA.objectId = 1;
        classA.property1 = "value1";

        classA.status = "new";
        marshal(jc, classA);

        classA.status = "deleted";
        marshal(jc, classA);
    }

    private static void marshal(JAXBContext jc, ClassA classA) throws Exception {
        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        if("deleted".equals(classA.status)) {
            marshaller.setProperty(MarshallerProperties.OBJECT_GRAPH, "deleted");
        }
        marshaller.marshal(classA, System.out);
    }

}

输出

下面是运行演示代码的输出。当 status等于deleted property1值未编码。

{
   "objectId" : 1,
   "status" : "new",
   "property1" : "value1"
}
{
   "objectId" : 1,
   "status" : "deleted"
}

---

我已经打开了以下增强请求，使这个用例更容易处理:

• http://bugs.eclipse.org/406375