spring MVC之使用@SessionAttributes时报异常

spring MVC之使用@SessionAttributes时报异常

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异常用下：

javax.servlet.ServletException: Cannot expose session attribute 'user_1' because of an existing model object of the same name

注意：我的项目是spring mvc3.5+freemarker的，控制器中使用的注解。在把对象用@SessionAttributes注解入到session时，报错。

这个时候，我们只需要在spring mvc的配置文件中，把freemarker的视图配置，加上：

<property name="allowSessionOverride" value="true"/>

 

完整的：

<bean id="freemarderConfig" class="org.springframework.web.servlet.view.freemarker.FreeMarkerConfigurer">
		<property name="templateLoaderPath" value="/WEB-INF/ftl/" />
		<property name="freemarkerVariables">
			<map>
				<entry key="xml_escape" value-ref="fmXmlEscape" />
			</map>
		</property>
		<property name="freemarkerSettings">
			<props>
				<prop key="defaultEncoding">UTF-8</prop>
				<prop key="template_update_delay">5</prop>
				<prop key="url_escaping_charset">UTF-8</prop>
				<prop key="locale">zh_CN</prop>
				<prop key="boolean_format">true,false</prop>
				<prop key="datetime_format">yyyy-MM-dd HH:mm:ss</prop>
				<prop key="date_format">yyyy-MM-dd</prop>
				<prop key="time_format">HH:mm:ss</prop>
				<prop key="number_format">0.######</prop>
				<prop key="whitespace_stripping">true</prop>
			</props>
		</property>
	</bean>
	<bean id="fmXmlEscape" class="freemarker.template.utility.XmlEscape" />
	<bean id="viewResolver" class="org.springframework.web.servlet.view.freemarker.FreeMarkerViewResolver">
		<property name="cache" value="true" />
		<property name="viewClass" value="org.springframework.web.servlet.view.freemarker.FreeMarkerView"/>
		<property name="suffix" value=".html" />
		<property name="exposeRequestAttributes" value="true" />
		<!-- <property name="allowSessionOverride" value="true"/> -->
		<property name="exposeSessionAttributes" value="true" />
		<property name="exposeSpringMacroHelpers" value="true" />
		<property name="contentType" value="text/html;charset=UTF-8" />
	</bean>