弹簧自动接线

Question

I have a Spring 3.0 project that I'm trying to wire up that has a dependency on a library project (also Spring 3.0) which has several classes that have properties being injected via org.springframework.beans.factory.annotation.Value .

I do not need the classes with injected properties to be loaded nor the properties to be injected. I only need one specific class to be autowired from the library project.

I keep getting the following exception:

Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private java.lang.String com.example.library.controller.App.dir; nested exception is java.lang.IllegalArgumentException: Could not resolve placeholder 'app.achDir'
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:502)
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:84)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:282)
... 38 more
Caused by: java.lang.IllegalArgumentException: Could not resolve placeholder 'app.achDir'
    at org.springframework.util.PropertyPlaceholderHelper.parseStringValue(PropertyPlaceholderHelper.java:173)
    at org.springframework.util.PropertyPlaceholderHelper.replacePlaceholders(PropertyPlaceholderHelper.java:125)
    at org.springframework.beans.factory.config.PropertyPlaceholderConfigurer$PlaceholderResolvingStringValueResolver.resolveStringValue(PropertyPlaceholderConfigurer.java:403)
    at org.springframework.beans.factory.support.AbstractBeanFactory.resolveEmbeddedValue(AbstractBeanFactory.java:736)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:713)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:703)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:474)
    ... 40 more

Here is the snippet of my applicationContext.xml. I have tried several versions of the following but the exclusions/inclusion filters do not appear to work.

<context:component-scan base-package="com.example.library" >
    <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Service"/>     
</context:component-scan>

I am using a PropertyPlaceholderConfigurer as suggested by one of the answers, this already existed in my project. Also, I have removed all of the component-scan and annotation-config from my Spring config files.

<!-- Define the other the old-fashioned way, with 'ignoreUnresolvablePlaceholders' set to TRUE -->  
<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
    <property name="locations">
        <list>
            <value>src/test/resources/my.properties</value>
            <value>my.properties</value>
        </list>
    </property>
   <property name="ignoreResourceNotFound" value="true"/>
</bean>

I should add that this error occurs while running a unit test that extends a super class with the following annotations:

@TransactionConfiguration(defaultRollback = true,transactionManager="txManager")
@Transactional
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath*:applicationContext.xml")
public abstract class BaseTest {

Answer 1

If you need a single component from that library, then it's probably better to define it explicitly. For example:

<bean id="..." class="com.example.library.SomeComponent">
 <!-- Bean initialization -->
</bean>

... or using Java-based container configuration .

If you actually need to scan this package, then make sure that all possible cases are handled properly by your exclusion filters. The stack trace suggests, that the component is annotated with @Controller, not @Service. However, there are other options, that should be considered as well, like @Component and @Repository.

Answer 2

Turns out there was a very simple solution that I overlooked. My library project jar was including its applicationContext.xml and I didn't realize it. I removed that, rebuilt the jar and its working properly.