8

我有一个使用 Spring (v4.0.5) 的 http 服务。它的 http 端点是使用 Spring Web MVC 配置的。响应是从模式生成的带有 JAXB2 注释的类。响应被包装，JAXBElement因为生成的 JAXB 类不@XmlRootElement包含注释（并且无法修改模式以对此进行修改）。我不得不为获得 XML 编组工作而奋斗。无论如何，它正在工作。

现在我正在设置 JSON 编组。我遇到的是获取具有JAXBElement“信封”特征的 JSON 文档。

{
  "declaredType": "io.github.gv0tch0.sotaro.SayWhat",
  "globalScope": true,
  "name": "{urn:io:github:gv0tch0:sotaro}say",
  "nil": false,
  "scope": "javax.xml.bind.JAXBElement$GlobalScope",
  "typeSubstituted": false,
  "value": {
    "what": "what",
    "when": "2014-06-09T15:56:46Z"
  }
}

我想要编组的只是value-object：

{
  "what": "what",
  "when": "2014-06-09T15:56:46Z"
}

这是我的 JSON 编组配置（弹簧上下文配置的一部分）：

<bean id="jsonConverter" class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
  <property name="objectMapper" ref="jacksonMapper" />
  <property name="supportedMediaTypes" value="application/json" />
</bean>

<bean id="jacksonMapper" class="com.fasterxml.jackson.databind.ObjectMapper">
  <property name="dateFormat">
    <bean class="java.text.SimpleDateFormat">
      <constructor-arg type="java.lang.String" value="yyyy-MM-dd'T'HH:mm:ss'Z'" />
      <property name="timeZone">
        <bean class="java.util.TimeZone" factory-method="getTimeZone">
          <constructor-arg type="java.lang.String" value="UTC" />
        </bean>
      </property>
    </bean>
  </property>
</bean>

我希望这可以通过配置ObjectMapper. 我想或者推出我自己的序列化程序可能会起作用。想法？建议？

4

2 回答 2

14

您可以为 JAXBElement 类注册一个mixin 注释，它将@JsonValue注释放在 JAXBElement.getValue() 方法上，使其返回值成为 JSON 表示。这是一个例子：

提供给的示例 .xsd 化学文件xjc。

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>

<xs:schema version="1.0" xmlns:xs="http://www.w3.org/2001/XMLSchema">
    <xs:element name="item" type="Thing"/>

    <xs:complexType name="Thing">
        <xs:sequence>
            <xs:element name="number" type="xs:long"/>
            <xs:element name="string" type="xs:string" minOccurs="0"/>
        </xs:sequence>
    </xs:complexType>

</xs:schema>

Java 主类：

public class JacksonJAXBElement {
    // a mixin annotation that overrides the handling for the JAXBElement
    public static interface JAXBElementMixin {
        @JsonValue
        Object getValue();
    }

    public static void main(String[] args) throws JAXBException, JsonProcessingException {
        ObjectFactory factory = new ObjectFactory();
        Thing thing = factory.createThing();
        thing.setString("value");
        thing.setNumber(123);
        JAXBElement<Thing> orderJAXBElement = factory.createItem(thing);

        System.out.println("XML:");
        JAXBContext jc = JAXBContext.newInstance(Thing.class);
        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
        marshaller.marshal(orderJAXBElement, System.out);
        System.out.println("JSON:");

        ObjectMapper mapper = new ObjectMapper();
        mapper.addMixInAnnotations(JAXBElement.class, JAXBElementMixin.class);
        System.out.println(mapper.writerWithDefaultPrettyPrinter()
                .writeValueAsString(orderJAXBElement));
    }
}

输出：

XML:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<item>
    <number>123</number>
    <string>value</string>
</item>
JSON:
{
  "number" : 123,
  "string" : "value"
}
于 2014-06-10T16:51:07.913 回答
3

对于一个完全配置的项目的例子，它：

  • 仅使用 Spring (v4.0.5) 进行内容协商和编组。
  • 使用 JAXB 生成响应的对象表示。
  • 支持 XML 和 JSON 内容协商。
  • 编组 JSON 响应时遵循 JAXB 注释。
  • 避免在响应对象周围泄漏JAXBElement-wrapper。

到这里来。

重要的部分是：

  • 一个 Jackson mixinJAXBElement ，它允许 Jackson在封送处理之前从 -wrapper中解开响应对象。
  • Spring 上下文配置，将 JSON 对象映射器配置为使用 Jackson，并将所述映射器配置为利用mixin并使用AnnotationIntrospectorPair 内省器（注意页面有点过时），将 JAXB 注释内省器配置为主要内省器（确保响应符合 XSD 的规定）并将 Jackson 的响应作为次要的（确保JAXBElement展开的mixin正在运行）。

混音：_

/**
 * Ensures, when the Jackson {@link ObjectMapper} is configured with it, that
 * {@link JAXBElement}-wrapped response objects when serialized as JSON documents
 * do not feature the JAXBElement properties; but instead the JSON-document that
 * results in marshalling the member returned by the {@link JAXBElement#getValue()}
 * call.
 * <p>
 * More on the usage and configuration options is available
 * <a href="http://wiki.fasterxml.com/JacksonMixInAnnotations">here</a>.
 */
public interface JaxbElementMixin {
  @JsonValue
  Object getValue();
}

Spring 上下文配置：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
  xmlns:aop="http://www.springframework.org/schema/aop"
  xmlns:context="http://www.springframework.org/schema/context" 
  xmlns:tx="http://www.springframework.org/schema/tx"
  xmlns:util="http://www.springframework.org/schema/util" 
  xmlns:mvc="http://www.springframework.org/schema/mvc"
  xmlns:oxm="http://www.springframework.org/schema/oxm"
  xsi:schemaLocation="
  http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
  http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
  http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
  http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd
  http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.0.xsd
  http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
  http://www.springframework.org/schema/oxm http://www.springframework.org/schema/oxm/spring-oxm-4.0.xsd">

  <context:component-scan base-package="io.github.gv0tch0.sotaro"/>

  <bean id="contentNegotiationManager" class="org.springframework.web.accept.ContentNegotiationManagerFactoryBean">
    <property name="favorPathExtension" value="false" />
    <property name="ignoreAcceptHeader" value="false" />
    <property name="useJaf" value="false" />
    <property name="defaultContentType" value="application/xml" />
    <property name="mediaTypes">
      <map>
        <entry key="xml" value="application/xml" />
        <entry key="json" value="application/json" />
      </map>
    </property>
  </bean>

  <bean id="typeFactory" class="com.fasterxml.jackson.databind.type.TypeFactory" factory-method="defaultInstance" />

  <bean id="jaxbIntrospector" class="com.fasterxml.jackson.module.jaxb.JaxbAnnotationIntrospector">
    <constructor-arg ref="typeFactory" />
  </bean>

  <bean id="jacksonIntrospector" class="com.fasterxml.jackson.databind.introspect.JacksonAnnotationIntrospector" />

  <bean id="annotationIntrospector" class="com.fasterxml.jackson.databind.introspect.AnnotationIntrospectorPair">
    <!-- Note that in order to get the best of both the JAXB annotation instrospector and the Mixin configuration
         the JAXB introspector needs to be the primary introspector, hence it needs to stay at position 0. -->
    <constructor-arg index="0" ref="jaxbIntrospector" />
    <constructor-arg index="1" ref="jacksonIntrospector" />
  </bean>

  <bean id="jacksonMapper" class="com.fasterxml.jackson.databind.ObjectMapper">
    <property name="annotationIntrospector" ref="annotationIntrospector" />
    <!-- The mixin ensures that when JAXBElement wrapped responses are marshalled as JSON the
         JAXBElement "envelope" gets discarded (which makes our JSON responses conform to spec). -->
    <property name="mixInAnnotations">
      <map key-type="java.lang.Class" value-type="java.lang.Class">
        <entry key="javax.xml.bind.JAXBElement" value="io.github.gv0tch0.sotaro.JaxbElementMixin" />
      </map>
    </property>
    <property name="dateFormat">
      <bean class="java.text.SimpleDateFormat">
        <constructor-arg type="java.lang.String" value="yyyy-MM-dd'T'HH:mm:ss'Z'" />
        <property name="timeZone">
          <bean class="java.util.TimeZone" factory-method="getTimeZone">
            <constructor-arg type="java.lang.String" value="UTC" />
          </bean>
        </property>
      </bean>
    </property>
  </bean>

  <bean id="jsonConverter" class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
    <property name="objectMapper" ref="jacksonMapper" />
    <property name="supportedMediaTypes" value="application/json" />
  </bean>

  <bean id="jaxbMarshaller" class="org.springframework.oxm.jaxb.Jaxb2Marshaller">
    <property name="supportJaxbElementClass" value="true" />
    <property name="contextPath" value="io.github.gv0tch0.sotaro" />
  </bean>

  <bean id="xmlConverter" class="org.springframework.http.converter.xml.MarshallingHttpMessageConverter">
    <constructor-arg ref="jaxbMarshaller" />
    <property name="supportedMediaTypes" value="application/xml" />
  </bean>

  <mvc:annotation-driven content-negotiation-manager="contentNegotiationManager">
    <mvc:message-converters register-defaults="false">
      <ref bean="xmlConverter" />
      <ref bean="jsonConverter" />
    </mvc:message-converters>
  </mvc:annotation-driven>

</beans>
于 2014-06-22T20:36:32.173 回答