Spring: import a module with specified environment - spring

Question

Is there anything that can achieve the equivalent of the below:
<import resource="a.xml">
<prop name="key" value="a"/>
</import>
<import resource="a.xml">
<prop name="key" value="b"/>
</import>
Such that the beans defined in resouce a would see the property key with two different values? The intention would be that this would be used to name the beans in the imports such that resource a.xml would appear:
<bean id="${key}"/>
And hence the application would have two beans named a and b now available with the same definition but as distinct instances. I know about prototype scope; it is not intended for this reason, there will be many objects created with interdepednencies that are not actually prototypes. Currently I am simply copying a.xml, creating b.xml and renaming all the beans using the equivalent of a sed command. I feel there must be a better way.

Answer 1

I suppose that PropertyPlaceholderConfigurers work on a per container basis, so you can't achieve this with xml imports.
Re The application would have two beans named a and b now available with the same definition but as distinct instances
I think you should consider creating additional application contexts(ClassPathXmlApplicationContext for example) manually, using your current application context as the parent application context.
So your many objects created with interdependencies sets will reside in its own container each.
However, in this case you will not be able to reference b-beans from a-container.
update you can postprocess the bean definitions(add new ones) manually by registering a BeanDefinitionRegistryPostProcessor specialized bean, but this solution also does not seem to be easy.
OK, here's my rough attempt to import xml file manually:
disclaimer: I'm very bad java io programmer actually so double check the resource related code :-)
public class CustomXmlImporter implements BeanDefinitionRegistryPostProcessor {
#Override
public void postProcessBeanFactory(
ConfigurableListableBeanFactory beanFactory) throws BeansException {
}
private Map<String, String> properties;
public void setProperties(Map<String, String> properties) {
this.properties = properties;
}
public Map<String, String> getProperties() {
return properties;
}
private void readXml(XmlBeanDefinitionReader reader) {
InputStream inputStream;
try {
inputStream = new ClassPathResource(this.classpathXmlLocation).getInputStream();
} catch (IOException e1) {
throw new AssertionError();
}
try {
Scanner sc = new Scanner(inputStream);
try {
sc.useDelimiter("\\A");
if (!sc.hasNext())
throw new AssertionError();
String entireXml = sc.next();
PropertyPlaceholderHelper helper = new PropertyPlaceholderHelper("${",
"}", null, false);
Properties props = new Properties();
props.putAll(this.properties);
String newXml = helper.replacePlaceholders(entireXml, props);
reader.loadBeanDefinitions(new ByteArrayResource(newXml.getBytes()));
} finally {
sc.close();
}
} finally {
try {
inputStream.close();
} catch (IOException e) {
throw new AssertionError();
}
}
}
private String classpathXmlLocation;
public void setClassPathXmlLocation(String classpathXmlLocation) {
this.classpathXmlLocation = classpathXmlLocation;
}
public String getClassPathXmlLocation() {
return this.classpathXmlLocation;
}
#Override
public void postProcessBeanDefinitionRegistry(
BeanDefinitionRegistry registry) throws BeansException {
XmlBeanDefinitionReader reader = new XmlBeanDefinitionReader(registry);
readXml(reader);
}
}
XML configuration:
<bean class="CustomXmlImporter">
<property name="classPathXmlLocation" value="a.xml" />
<property name="properties">
<map>
<entry key="key" value="a" />
</map>
</property>
</bean>
<bean class="CustomXmlImporter">
<property name="classPathXmlLocation" value="a.xml" />
<property name="properties">
<map>
<entry key="key" value="b" />
</map>
</property>
</bean>
this code loads the resources from classpath. I would think twice before doing something like that, anyway, you can use this as a starting point.