How to return a long property as JSON string value with JAXB

问题

I have a Java class annotated with @XmlRootElement. This Java class has a long property (private long id) that I want to return to a JavaScript-client.

I create the JSON as follows:

MyEntity myInstance = new MyEntity("Benny Neugebauer", 2517564202727464120);
StringWriter writer = new StringWriter();
JSONConfiguration config = JSONConfiguration.natural().build();
Class[] types = {MyEntity.class};
JSONJAXBContext context = new JSONJAXBContext(config, types);
JSONMarshaller marshaller = context.createJSONMarshaller();
marshaller.marshallToJSON(myInstance, writer);
json = writer.toString();
System.out.println(writer.toString());

This will be generated:

{"name":"Benny Neugebauer","id":2517564202727464120}

But the problem is that the long value is too large for the JavaScript client. Therefore, I would like to return this value as a string (without making the long a string in Java).

Is there an annotation (or something similar) that can generate the following?

{"name":"Benny Neugebauer","id":"2517564202727464120"}

回答1:

Note: I'm the EclipseLink JAXB (MOXy) lead and a member of the JAXB (JSR-222) expert group.

Below is how you could accomplish this use case with MOXy as your JSON provider.

MyEntity

You would annotate your long property with @XmlSchemaType(name="string") to indicate that it should be marshalled as a String.

package forum11737597;

import javax.xml.bind.annotation.*;

@XmlRootElement
public class MyEntity {

    private String name;
    private long id;

    public MyEntity() {
    }

    public MyEntity(String name, long id) {
        setName(name);
        setId(id);
    }

    public String getName() {
        return name;
    }

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

    @XmlSchemaType(name="string")
    public long getId() {
        return id;
    }

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

}

jaxb.properties

To configure MOXy as your JAXB provider you need to include a file called jaxb.properties in the same package as your domain model (see: http://blog.bdoughan.com/2011/05/specifying-eclipselink-moxy-as-your.html).

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

Demo

I have modified your sample code to show what it would look like if you used MOXy.

package forum11737597;

import java.io.StringWriter;
import java.util.*;
import javax.xml.bind.*;
import org.eclipse.persistence.jaxb.JAXBContextProperties;

public class Demo {

    public static void main(String[] args) throws Exception {
        MyEntity myInstance = new MyEntity("Benny Neugebauer", 2517564202727464120L);
        StringWriter writer = new StringWriter();
        Map<String, Object> config = new HashMap<String, Object>(2);
        config.put(JAXBContextProperties.MEDIA_TYPE, "application/json");
        config.put(JAXBContextProperties.JSON_INCLUDE_ROOT, false);
        Class[] types = {MyEntity.class};
        JAXBContext context = JAXBContext.newInstance(types, config);
        Marshaller marshaller = context.createMarshaller();
        marshaller.marshal(myInstance, writer);
        System.out.println(writer.toString());
    }

}

Output

Below is the output from running the demo code:

{"id":"2517564202727464120","name":"Benny Neugebauer"}

For More Information

http://blog.bdoughan.com/2011/08/json-binding-with-eclipselink-moxy.html

来源：https://stackoverflow.com/questions/11737597/how-to-return-a-long-property-as-json-string-value-with-jaxb

标签

json

string

jaxb

marshalling

long-integer