使用JAXB取消使用namspace编组XML时的空值

Question

I have an issue while un-marshalling simple XML (a subset of CSDL) using JAXB.
Someone already tried to assist me in the past ( here ), however it is partially worked and I don't know what to do...
Please consider the following XML:

<edmx:Edmx xmlns:edmx="http://schemas.microsoft.com/ado/2007/06/edmx">
  <edmx:DataServices xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata" m:DataServiceVersion="3.0">
    <Schema xmlns:cg="http://schemas.microsoft.com/ado/2006/04/codegeneration" xmlns:sap="http://www.sap.com/Protocols/SAPData" xmlns="http://schemas.microsoft.com/ado/2009/11/edm" xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata" xmlns:d="http://schemas.microsoft.com/ado/2007/08/dataservices" Namespace="myNS">
    </Schema>
  </edmx:DataServices>
</edmx:Edmx>

As I was told, I have a package-info.java file that looks like (in the same package):

@XmlSchema(
  namespace="http://schemas.microsoft.com/ado/2007/06/edmx",
  elementFormDefault=XmlNsForm.QUALIFIED,
  xmlns={
          @XmlNs(prefix="edmx", namespaceURI="http://schemas.microsoft.com/ado/2007/06/edmx"),
          @XmlNs(prefix="", namespaceURI="http://schemas.microsoft.com/ado/2009/11/edm"),
          @XmlNs(prefix="m", namespaceURI="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata")                                
  }
)
@XmlAccessorType(XmlAccessType.FIELD)
package com.sap.ndb.studio.rdl.csdlparser.jaxb.objects;

import javax.xml.bind.annotation.*;

In addition, I have the following data structure:

Edmx.java

package com.sap.ndb.studio.rdl.csdlparser.jaxb.objects;

import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name = "Edmx")
public class Edmx {

    @XmlElement(name = "DataServices")
    private DataService dataService;

    public DataService getDataService() {
          return dataService;
    }
}

DataService.java

package com.sap.ndb.studio.rdl.csdlparser.jaxb.objects;

import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class DataService {

    @XmlElement(name = "Schema")
    private Schema schema;

    @XmlAttribute(name = "DataServiceVersion")
    private double version;

    public Schema getSchema() {
      return schema;
    }
 }

Schema.java

package com.sap.ndb.studio.rdl.csdlparser.jaxb.objects;

@XmlRootElement
public class Schema {
  ....
}

Notice: in Schema.java I have some implementation which does not related to the XML so I have took it off (internal logic).

After un-marshalling the XML using the JAXB, The returned Edmx object contains null values both in 'schema' and 'version' members, although I have mentioned all xmlns parameters in my package-info.java.

Anyone? :(

Answer 1

UPDATE

In my answer to one of your previous questions I provider a mapping for the model from this question.

• Error while trying to unmarshal EDMX with JAXB

I have updated this answer to address the following comment that you made:

Why should I declare 'namespace=schemas.microsoft.com/ado/2009/11/edm'; in my @XmlElement? sorry for being annoying (this is my first experience with JAXB) but I just gonna have a long XML with many @XmlElement nodes similar to the 'Schema' and I would like to declare the namespace for them only once...

You can reduce the number of times you need to declare a namespace by organizing your model classes into different packages based on the namespace that they correspond to.

Package 1 for Namespace http://schemas.microsoft.com/ado/2007/06/edmx

package-info

For each package we will use the @XmlSchema annotation to specify the namespace qualification. In this example we only need to specify the namespace for this particular package.

@XmlSchema(
        namespace="http://schemas.microsoft.com/ado/2007/06/edmx",
        elementFormDefault=XmlNsForm.QUALIFIED,
        xmlns={
                @XmlNs(
                    prefix="edmx", 
                    namespaceURI="http://schemas.microsoft.com/ado/2007/06/edmx"
                ),
        }
)
@XmlAccessorType(XmlAccessType.FIELD)
package forum14875956.edmx;

import javax.xml.bind.annotation.*;

Edmx

The XML elements corresponding to the Edmx class will be namespace qualified according to what we defined on the @XmlSchema annotation for this package.

package forum14875956.edmx;

import javax.xml.bind.annotation.*;

@XmlRootElement(name = "Edmx")
public class Edmx {

    @XmlElement(name = "DataServices")
    private DataService dataService;

    public DataService getDataService() {
        return dataService;
    }

}

DataService

The DataService class contains a reference to a class corresponding to a different XML namespace. If the Schema class was in the same package we could use the @XmlElement annotation to override the namespace qualification. Since Schema is in a different package we can use the @XmlElementRef annotation. This tells JAXB to derive the element information from the root element configured for that class.

package forum14875956.edmx;

import javax.xml.bind.annotation.*;
import forum14875956.schema.Schema;

public class DataService {

    //@XmlElement(namespace="http://schemas.microsoft.com/ado/2009/11/edm", name="Schema")
    @XmlElementRef
    private Schema schema;

    public Schema getSchema() {
        return schema;
    }

}

Package 2 for Namespace http://schemas.microsoft.com/ado/2009/11/edm

Again we will use the @XmlSchema to declare the namespace information for the second package.

package-info

@XmlSchema(
        namespace="http://schemas.microsoft.com/ado/2009/11/edm",
        elementFormDefault=XmlNsForm.QUALIFIED,
        xmlns={
                @XmlNs(
                    prefix="", 
                    namespaceURI="http://schemas.microsoft.com/ado/2009/11/edm"
                )
        }
)
@XmlAccessorType(XmlAccessType.FIELD)
package forum14875956.schema;

import javax.xml.bind.annotation.*;

Schema

The elements in the Schema class will be namespace qualified based namespace information in the @XmlSchema annotation for its package.

package forum14875956.schema;

import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name="Schema")
public class Schema {

}

---

ORIGINAL ANSWER

You need to include the namespace URI on the mapping for the schema property:

@XmlRootElement
public class DataService {

    @XmlElement(name = "Schema" , namespace="http://schemas.microsoft.com/ado/2009/11/edm")
    private Schema schema;

    @XmlAttribute(name = "DataServiceVersion")
    private double version;

    public Schema getSchema() {
      return schema;
    }
 }

Full Example

A little while I ago I answered one of your questions providing a complete mapping for this model:

• Error while trying to unmarshal EDMX with JAXB