Jquery Error executing FreeMarker template：The following has evaluated to null or missing，空指針異常

異常如下：

2019-09-05 17:47:54.941 |-ERROR [http-nio-8089-exec-7] freemarker.runtime [59] -| Error executing FreeMarker template
freemarker.core.InvalidReferenceException: The following has evaluated to null or missing:
==> info.url  [in template "admin/wechatPublic/edit.ftl" at line 27, column 98]

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Tip: It's the step after the last dot that caused this error, not those before it.
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Tip: If the failing expression is known to be legally refer to something that's sometimes null or missing, either specify a default value like myOptionalVar!myDefault, or use <#if myOptionalVar??>when-present<#else>when-missing</#if>. (These only cover the last step of the expression; to cover the whole expression, use parenthesis: (myOptionalVar.foo)!myDefault, (myOptionalVar.foo)??
----

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FTL stack trace ("~" means nesting-related):
	- Failed at: ${info.url}  [in template "admin/wechatPublic/edit.ftl" at line 27, column 96]
----
	at freemarker.core.InvalidReferenceException.getInstance(InvalidReferenceException.java:134)
	at freemarker.core.EvalUtil.coerceModelToTextualCommon(EvalUtil.java:451)
	at freemarker.core.EvalUtil.coerceModelToStringOrMarkup(EvalUtil.java:374)
	at freemarker.core.DollarVariable.calculateInterpolatedStringOrMarkup(DollarVariable.java:96)
	at freemarker.core.DollarVariable.accept(DollarVariable.java:59)
	at freemarker.core.Environment.visit(Environment.java:327)
	at freemarker.core.Environment.visit(Environment.java:333)
	at freemarker.core.Environment.process(Environment.java:306)
	at freemarker.template.Template.process(Template.java:386)
	at org.springframework.web.servlet.view.freemarker.FreeMarkerView.processTemplate(FreeMarkerView.java:367)
	at org.springframework.web.servlet.view.freemarker.FreeMarkerView.doRender(FreeMarkerView.java:284)
	at org.springframework.web.servlet.view.freemarker.FreeMarkerView.renderMergedTemplateModel(FreeMarkerView.java:234)
。。。。。。。

解決辦法：

1.配置 FreeMarker 時

<!-- freemarker的配置 -->
<bean id="freeMarkerConfigurer" class="com.biomatch.qadm.util.ShiroTagFreeMarkerConfigurer">
	<property name="preferFileSystemAccess" value="false" />
	<property name="templateLoaderPath" value="classpath:/view/" />
	<property name="defaultEncoding" value="UTF-8" />
	<property name="freemarkerSettings">
		<props>
			<!--用於解決前端報空指針問題-->
			<prop key="classic_compatible">true</prop>
			<prop key="template_update_delay">10</prop>
			<prop key="locale">zh_CN</prop>
			<prop key="datetime_format">yyyy-MM-dd HH:mm:ss</prop>
			<prop key="date_format">yyyy-MM-dd</prop>
			<prop key="number_format">#.##</prop>
		</props>
	</property>
	<property name="freemarkerVariables">
		<map>
			<entry key="ctx" value="/queue-admin"></entry>
			<!-- <entry key="test" value="'test'"></entry> -->
		</map>
	</property>
</bean>

添加:

<!--用於解決前端報空指針問題-->
<prop key="classic_compatible">true</prop>

2.前端判斷null修改

<input type="text" class="form-control" id="url" value=${info.url}>

改爲

<input type="text" class="form-control" id="url" value=${(info.url)?default('')}>