How to inject spring beans into a jsp 2.0 SimpleTag?

java spring jsp jsp-tags
krosenvold picture krosenvold · Aug 18, 2009 · Viewed 23.1k times · Source

Currently my jsp 2.0 tags that need spring beans use this code:

ac = WebApplicationContextUtils.getWebApplicationContext( servletContext);
ac.getBeansOfType(MyRequestedClass.class);

The I just get the first matching bean.

This code works fine, but has the undesired drawback that I spend about half my page rendering time looking up spring beans, since this happens every time a tag is invoked. I was thinking maybe to put the bean into application scope or at least session scope. But what's really the smartest way of handling this problem ?

Answer

skaffman picture skaffman · Aug 18, 2009

My first thought is, are you sure the calls to spring are expensive? This stuff is pretty heavily optimized, so make sure it's actually a problem before trying to optimize it.

Assuming it is a problem, then an alternative is the exposeContextBeansAsAttributes and exposedContextBeanNames properties of InternalResourceViewResolver. You can use one or the other (but not both) to expose some or all of your beans as JSP attributes.

This raises the possibly of actually injecting Spring beans into your tag classes. For example, in your Spring context you can have:

<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
  <property name="exposeContextBeansAsAttributes" value="true"/>
</bean>

<bean id="myBean" class="com.x.MyClass"/>

Your JSP:

<MyTag thing="${myBean}"/>

SO if MyTag defines an attribute thing of type MyClass, the myBean spring bean should get injected as a normal JSP attribute.

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