Java：XStream 下划线

Why do field names suddenly have double underscores in the generated XML?

XStream maps Java class names and field names to XML tags or attributes. Unfortunately this mapping cannot be 1:1, since some characters used for identifiers in Java are invalid in XML names. Therefore XStream uses an XmlFriendlyNameCoder to replace these characters with a replacement. By default this NameCoder uses an underscore as escape character and has therefore to escape the underscore itself also. You may provide a different configured instance of the XmlFriendlyNameCoder or a complete different implementation like the NoNameCoder to prevent name coding at all. However it is your responsibility then to ensure, that the resulting names are valid for XML.

1、1.4及以后

<bean id="marshaller" class="org.springframework.oxm.xstream.AnnotationXStreamMarshaller">
    <property name="streamDriver">
        <bean class="com.thoughtworks.xstream.io.xml.StaxDriver">
            <constructor-arg>
                <bean class="com.thoughtworks.xstream.io.naming.NoNameCoder()">
                </bean>
            </constructor-arg>
        </bean>
    </property>
</bean>

2、1.4之前

<bean id="marshaller" class="org.springframework.oxm.xstream.AnnotationXStreamMarshaller">
    <property name="streamDriver">
        <bean class="com.thoughtworks.xstream.io.xml.XppDriver">
            <constructor-arg>
                <bean class="com.thoughtworks.xstream.io.xml.XmlFriendlyReplacer">
                    <constructor-arg index="0" value="_-"/>
                    <constructor-arg index="1" value="_"/>
                </bean>
            </constructor-arg>
        </bean>
    </property>
</bean>

3、注册到spring mvc

<mvc:annotation-driven>
  <mvc:message-converters>
    <bean class="org.springframework.http.converter.xml.MarshallingHttpMessageConverter">
        <property name="marshaller" ref="marshaller" />
        <property name="unmarshaller" ref="marshaller" />
    </bean>
  </mvc:message-converters>
</mvc:annotation-driven>

<!-- 根据客户端的不同的请求决定不同的view进行响应, 如 /blog/1.json /blog/1.xml -->
<bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">
	<property name="ignoreAcceptHeader" value="true" />
	<property name="defaultContentType" value="application/json" />
	<!-- 扩展名至mimeType的映射,即 /blog.json => application/json -->
	<property name="mediaTypes">
		<map>
			<entry key="json" value="application/json" />
			<entry key="xml" value="application/xml" />
		</map>
	</property>
	<!-- 用于开启 /blog/123?format=json 的支持 -->
	<property name="favorParameter" value="false" />
	<property name="viewResolvers">
		<list>
			<bean class="org.springframework.web.servlet.view.BeanNameViewResolver" />
			<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
				<property name="viewClass" value="org.springframework.web.servlet.view.JstlView" />
				<property name="prefix" value="/pages" />
				<property name="suffix" value=".jsp"></property>
			</bean>
		</list>
	</property>
	<property name="defaultViews">
		<list>
			<bean  class="org.springframework.web.servlet.view.json.MappingJackson2JsonView">
				<property  name="extractValueFromSingleKeyModel" value="true" />
			</bean>
			<bean  class="org.springframework.web.servlet.view.xml.MarshallingView">
				<property name="marshaller">
					<bean  class="org.springframework.oxm.xstream.XStreamMarshaller">
						<property name="autodetectAnnotations" value="true"/>
						<!-- 针对bean中下划线处理 -->
						<property name="streamDriver">
							<bean class="com.thoughtworks.xstream.io.xml.StaxDriver">
								<constructor-arg>
									<bean class="com.thoughtworks.xstream.io.naming.NoNameCoder" />
								</constructor-arg>
							</bean>
						</property>
					</bean>
				</property>
			</bean>
		</list>
	</property>
</bean>