Jaxb 复杂的 xml 解组

Question

我在解组下面的嵌套 xml 时遇到问题。如果我遗漏了什么，有人可以告诉我。
body 标签可以包含任何 Jaxb 带注释的 obj。
我是否必须创建一个自定义适配器来编组/解组此类 xml？

输入 XML

<?xml version="1.0" encoding="UTF-8"?>
<serviceRq xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="serviceRq">
  <body>   
    <createRq>
       <id>1234</id>
    </createRq>
  </body>
</serviceRq>

我的 Jaxb 注释类是：

@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "serviceRq")
public class ServiceRq{    
    private Object body;
    <!-- getters and setters omitted-->
}

这里，body 可以是任何带有 jaxb 注释的对象，在本例中是它的 CreateRq。

@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "createRq")
public class CreateRq{    
    private String id;
    <!-- getters and setters omitted-->
}

我正在寻找一种通用方法来支持输入 xml 正文中的任何 Jaxb 注释对象。

Answer 1

您可以使用@XmlAnyElement(lax=true) 和XmlAdapter 来处理此用例：

ServiceRq

import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;
import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;

@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "serviceRq")
public class ServiceRq{    

    @XmlJavaTypeAdapter(value=BodyAdapter.class)
    private Object body;
    // getters and setters omitted
}

BodyAdapter

import javax.xml.bind.annotation.adapters.XmlAdapter;

public class BodyAdapter extends XmlAdapter<Body, Object>{

    @Override
    public Object unmarshal(Body v) throws Exception {
        return v.getValue();
    }

    @Override
    public Body marshal(Object v) throws Exception {
        Body body = new Body();
        body.setValue(v);
        return body;
    }

}

身体

import javax.xml.bind.annotation.XmlAnyElement;

public class Body {

    private Object value;

    @XmlAnyElement(lax=true)
    public Object getValue() {
        return value;
    }

    public void setValue(Object value) {
        this.value = value;
    }

}

CreateRq

import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;

@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "createRq")
public class CreateRq{    
    private String id;
    // getters and setters omitted
}

演示

import java.io.File;

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

public class Demo {

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

        Unmarshaller unmarshaller = jc.createUnmarshaller();
        ServiceRq serviceRq = (ServiceRq) unmarshaller.unmarshal(new File("input.xml"));

        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        marshaller.marshal(serviceRq, System.out);

    }

}

更多信息

• http://bdoughan.blogspot.com/2010/08/using-xmlanyelement-to-build-generic.html
• http://bdoughan.blogspot.com/2010/07/xmladapter-jaxbs-secret-weapon.html
• http://bdoughan.blogspot.com/2010/12/jaxb-and-immutable-objects.html
• http://bdoughan.blogspot.com/2010/12/represent-string-values-as-element.html

Answer 2

您可以使用@XmlAnyElement(lax=true) 和EclipseLink JAXB (MOXy) 中的@XmlPath 扩展来处理这个用例（注意：我是MOXy 负责人）。有关适用于任何 JAXB 实现（Metro、MOXy、JaxMe 等）的方法，请参阅：Jaxb complex xml unmarshall。

ServiceRq

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlAnyElement;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;

import org.eclipse.persistence.oxm.annotations.XmlPath;

@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "serviceRq")
public class ServiceRq{    

    @XmlPath("body/createRq")
    @XmlAnyElement(lax=true)
    private Object body;
    // getters and setters omitted
}

CreateRq

import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;

@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "createRq")
public class CreateRq{    
    private String id;
    // getters and setters omitted
}

演示

import java.io.File;

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

public class Demo {

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

        Unmarshaller unmarshaller = jc.createUnmarshaller();
        ServiceRq serviceRq = (ServiceRq) unmarshaller.unmarshal(new File("input.xml"));

        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        marshaller.marshal(serviceRq, System.out);

    }
}

jaxb.properties

要将 MOXy 用作您的 JAXB 提供程序，您必须在与您的域模型相同的包中包含一个名为 jaxb.properties 的文件，其中包含以下条目：

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

更多信息

• http://bdoughan.blogspot.com/2010/08/using-xmlanyelement-to-build-generic.html
• http://bdoughan.blogspot.com/2011/05/specifying-eclipselink-moxy-as-your.html
• http://bdoughan.blogspot.com/2010/09/xpath-based-mapping-geocode-example.html
• http://bdoughan.blogspot.com/2011/03/map-to-element-based-on-attribute-value.html