JAXB 映射到 JSON [英] JAXB Mapping to JSON
问题描述
我编写了一个 JAX-RS (Jersey) REST 服务，它接受 ONIX XML 格式的 XML 消息.通常，我已经使用 xjc 从给定的模式生成了 JAXB 绑定所需的所有类.总共有 500 多个类，我无法修改它们.
I have written a JAX-RS (Jersey) REST Service, which accepts XML messages of ONIX XML format. Generally, I have generated all the required classes for JAXB binding from the given schema with xjc. There are more than 500 classes overall and I cannot modify them.
现在，当我有一个 JAXB 映射对象时，我需要将它存储到数据库中.我使用 mongoDb，所以消息格式应该是 JSON.我尝试使用带有 JAXB 模块的 Jackson 将 JAXB 对象转换为 JSON，这在存储数据方面效果很好.但是当我尝试将 JSON 转换回 JAXB 对象时，它会抛出一个与 JAXBElement 以某种方式连接的异常.在 google 中，我发现 Jackson 不支持 JAXBElement，我必须解决这个问题.但是我不能这样做，因为我无法修改 JAXB 生成的类.
Now, when I have a JAXB-mapped object, I need to store it to the database. I work with mongoDb, so the message format should be JSON. I tried to use Jackson with JAXB module to convert JAXB-object into JSON, which works pretty fine with storing the data. But when I try to convert the JSON back into the JAXB object, it throws an exception connected somehow with the JAXBElement. In google I found out that the JAXBElement is not supported in Jackson and I have to work around this issue. But I cant do it because I cannot modify JAXB-generated classes.
有没有办法用其他方式将 JAXB 对象映射到 JSON，但是这将遵循整个 JAXB 规范，以便我将来从 JSON 转换为 JAXB 对象和签证没有问题?
Is there a way to map JAXB Objects into JSON with some other means, but which will follow the whole JAXB specification so that I have no problems in the future converting from JSON to the JAXB object and visa vera?
推荐答案
注意:我是EclipseLink JAXB (MOXy) 领导和成员 JAXB (JSR-222) 专家组.
Note: I'm the EclipseLink JAXB (MOXy) lead and a member of the JAXB (JSR-222) expert group.
如果您不能使用 Jackson，您的用例将适用于 MOXy.
If you can't do it with Jackson, you use case will work with MOXy.
Foo
这是一个包含 JAXBElement 类型字段的示例类.
Here is a sample class that contains a field of type JAXBElement.
import javax.xml.bind.JAXBElement;
import javax.xml.bind.annotation.*;
@XmlAccessorType(XmlAccessType.FIELD)
public class Foo {
@XmlElementRef(name="bar")
private JAXBElement<Bar> bar;
}
条形
public class Bar {
}
对象工厂
import javax.xml.bind.JAXBElement;
import javax.xml.bind.annotation.*;
import javax.xml.namespace.QName;
@XmlRegistry
public class ObjectFactory {
@XmlElementDecl(name = "bar")
public JAXBElement<Bar> createBar(Bar bar) {
return new JAXBElement<Bar>(new QName("bar"), Bar.class, bar);
}
}
独立演示代码
下面是一些演示代码，您可以在 Java SE 中运行以查看一切正常:
Standalone Demo Code
Below is some demo code you can run in Java SE to see that everything works:
演示
import java.util.*;
import javax.xml.bind.*;
import javax.xml.transform.stream.StreamSource;
import org.eclipse.persistence.jaxb.JAXBContextProperties;
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[] {Foo.class, ObjectFactory.class}, properties);
Unmarshaller unmarshaller = jc.createUnmarshaller();
StreamSource json = new StreamSource("src/forum19158056/input.json");
Foo foo = unmarshaller.unmarshal(json, Foo.class).getValue();
Marshaller marshaller = jc.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
marshaller.marshal(foo, System.out);
}
}
input.json/输出
{"bar" : {} }
使用 JAX-RS 运行
以下链接将帮助您在 JAX-RS 服务中利用 MOXy:
Running with JAX-RS
The following links will help you leverage MOXy in a JAX-RS service:
- http://blog.bdoughan.com/2012/05/moxy-as-your-jax-rs-json-provider.html
- http://blog.bdoughan.com/2013/06/moxy-is-new-default-json-binding.html
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