使用JAXB灵活编组 [英] Flexible marshalling with JAXB
问题描述
我希望有一种灵活的编组方式。单个对象的详细版本和多个对象版本的详细版本。
例如，考虑我的部门模型：
获取/位置/ 1：
< location id ='1'>
< link rel =selfhref =http://example.com/locations/1/>
< link rel =parenthref =http://example.com/serviceareas/1/>
< name> location 01< / name>
< departments>
< department id ='1'>
< link rel =selfhref =http://example.com/departments/1/>
< name> department 01< / name>
< / department>
< department id ='2'>
< link rel =selfhref =http://example.com/departments/2/>
< name> department 02< / name>
< / department>
< department id ='3'>
< link rel =selfhref =http://example.com/departments/3/>
< name> department 03< / name>
< / department>
< / departments>
< / location>
GET / department / 1：
< department id ='1'>
< link rel =selfhref =http://example.com/departments/1/>
< link rel =parenthref =http://example.com/locations/1/>
< name> department 01< / name>
< abbr> dept 01< / abbr>
....
< special>重症监护< / special>
< / department>
有没有办法做到这一点？我需要有单独的实体对象吗？一个引用CRUD操作表而另一个引用列表？
注意：我是 EclipseLink JAXB（MOXy） 领导，以及 JAXB 2（JSR-222） 专家如果您使用的是 EclipseLink JAXB（MOXy） strong>您可以利用外部绑定文档将第二个映射应用于 Department 类。
ContextResolver
在 JAX-RS 环境中，您可以通过 ContextResolver 来利用MOXy的外部绑定文档：
import java.io. *;
import java.util。*;
import javax.ws.rs.Produces;
import javax.ws.rs.ext。*;
import javax.xml.bind。*;
import org.eclipse.persistence.jaxb.JAXBContextFactory;
@Provider
@Produces（{application / xml，application / json}）
公共类DepartmentContextResolver实现ContextResolver< JAXBContext> {
private JAXBContext jc;
public DepartmentContextResolver（）{
try {
Map< String，Object> props = new HashMap< String，Object>（1）;
props.put（JAXBContextFactory.ECLIPSELINK_OXM_XML_KEY，example / bindings.xml）;
jc = JAXBContext.newInstance（new Class [] {Department.class}，props）;
} catch（JAXBException e）{
抛出新的RuntimeException（e）;
}
}
public JAXBContext getContext（Class<？> clazz）{
if（Department.class == clazz）{
return jc ;
}
返回null;
}
}
更多信息
- http://blog.bdoughan.com/2011/04/moxys-xml-metadata-in- jax-rs-service.html
- http://blog.bdoughan.com/2010/08/creating-restful-web-service-part-35.html
外部装订文件
默认情况下，MOXy的外部绑定文档用于扩充带注释的模型，但如果设置 xml-mapping-metadata-complete 标志，它将完全覆盖允许您的注释应用完全不同的映射：
< xml-bindings
xmlns =http：//www.eclipse .ORG /的EclipseLink / XSD文件/持续ence / oxm
package-name =example
xml-mapping-metadata-complete =true>
...
< / xml-bindings>
更多信息
- http://blog.bdoughan.com/2011/09/mapping-objects-to-multiple-xml-schemas.html
- http://blog.bdoughan.com/2010/12/ extend-jaxb-represent-annotations.html
更新
此更新旨在解答您在一条评论中提出的一些问题：
1。每个ContentResolver应该/可以拥有自己的绑定文件吗？
是每个 ContextResolver 应该有自己的绑定文件。引入新的 ContextResolver 的主要原因是表示辅助映射。
2。我可以为每个ContentResolver设置多个（这会给我一些同一个类的渲染，创建一个'视图'的排序），也许在构造函数中指定它的位置？
对于单个 ContextResolver ，您可以在多个绑定文件中表达元数据，但它们将合并为一组映射。这意味着单个 ContentResolver 不能拥有单个类的多个视图。单独的 ContextResolver 用于表示辅助映射。
3。绑定文件应该驻留在哪里？
我建议从类路径加载元数据文件。
4。我可以看到如何在Resource的GET方法中轻松指定ContentResolver，但是如果对象嵌入另一个（JPA）对象中，如何做到这一点？在嵌入对象的getter / setter中？
你的JAX-RS实现应该拿起 ContextResolver 因为它是用 @Provider 注释的。用于类的 ContextResolver 将取决于您如何实现 getContext 方法：
public JAXBContext getContext（Class<？> clazz）{
if（Customer.class == clazz）{
return jc;
}
返回null;
}
I'm hoping to have a flexible way of marshalling objects. A verbose version for single objects and a less-verbose version for multiple object versions.
For example, consider my department model:
GET /locations/1:
<location id='1'>
<link rel="self" href="http://example.com/locations/1"/>
<link rel="parent" href="http://example.com/serviceareas/1"/>
<name>location 01</name>
<departments>
<department id='1'>
<link rel="self" href="http://example.com/departments/1"/>
<name>department 01</name>
</department>
<department id='2'>
<link rel="self" href="http://example.com/departments/2"/>
<name>department 02</name>
</department>
<department id='3'>
<link rel="self" href="http://example.com/departments/3"/>
<name>department 03</name>
</department>
</departments>
</location>
GET /department/1:
<department id='1'>
<link rel="self" href="http://example.com/departments/1"/>
<link rel="parent" href="http://example.com/locations/1"/>
<name>department 01</name>
<abbr>dept 01</abbr>
....
<specialty>critical care</specialty>
</department>
Is there a way to do this? Would I need to have separate entity objects? One that references the table for CRUD operations and another for lists?
Note: I'm the EclipseLink JAXB (MOXy) lead, and a member of the JAXB 2 (JSR-222) expert group.
Your question is tagged EclipseLink, if you are using EclipseLink JAXB (MOXy) you can take advantage of the external binding document to apply a second mapping to the Department class.
ContextResolver
In a JAX-RS environment you can leverage MOXy's external binding document through a ContextResolver:
import java.io.*;
import java.util.*;
import javax.ws.rs.Produces;
import javax.ws.rs.ext.*;
import javax.xml.bind.*;
import org.eclipse.persistence.jaxb.JAXBContextFactory;
@Provider
@Produces({"application/xml", "application/json"})
public class DepartmentContextResolver implements ContextResolver<JAXBContext> {
private JAXBContext jc;
public DepartmentContextResolver() {
try {
Map<String, Object> props = new HashMap<String, Object>(1);
props.put(JAXBContextFactory.ECLIPSELINK_OXM_XML_KEY, "example/bindings.xml");
jc = JAXBContext.newInstance(new Class[] {Department.class} , props);
} catch(JAXBException e) {
throw new RuntimeException(e);
}
}
public JAXBContext getContext(Class<?> clazz) {
if(Department.class == clazz) {
return jc;
}
return null;
}
}
For More Information
- http://blog.bdoughan.com/2011/04/moxys-xml-metadata-in-jax-rs-service.html
- http://blog.bdoughan.com/2010/08/creating-restful-web-service-part-35.html
External Binding Document
By default MOXy's external binding document is used to augment the annotated model, but if you set the xml-mapping-metadata-complete flag it will completely override the annotations allowing you to apply a completely different mapping:
<xml-bindings
xmlns="http://www.eclipse.org/eclipselink/xsds/persistence/oxm"
package-name="example"
xml-mapping-metadata-complete="true">
...
</xml-bindings>
For More Information
- http://blog.bdoughan.com/2011/09/mapping-objects-to-multiple-xml-schemas.html
- http://blog.bdoughan.com/2010/12/extending-jaxb-representing-annotations.html
UPDATE
This update is to address a number of questions you asked in one of your comments:
1 . Should/can each ContentResolver have its own binding file?
Yes each ContextResolver should have its own binding file. The main reason for introducing a new ContextResolver is to represent a secondary mapping.
2 . Can I have more than one for each ContentResolver (this would give me a number of renderings of the same class, creating a 'view' of sorts), perhaps specifying its location in the constructor?
For a single ContextResolver you can express the metadata across multiple binding files, but they will be combined into a single set of mappings. This means that a single ContentResolver cannot have multiple views of a single class. A separate ContextResolver is used to represent a secondary mapping.
3 . Where should the binding files reside?
I recommend loading the metadata file from the class path.
4 . I can see how the ContentResolver could be easily specified in a Resource's GET method, but how would this be done if the object is embedded in another (JPA) object? In the embedded object's getter/setter?
Your JAX-RS implementation should pick up your ContextResolver because it is annotated with @Provider. The ContextResolver used for a class will depend on how you implement the getContext method:
public JAXBContext getContext(Class<?> clazz) {
if(Customer.class == clazz) {
return jc;
}
return null;
}
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