occur "Could not resolve placeholder KName" exception when start a webApp - java

here is a blog of Spring:
http://blog.springsource.org/2011/02/15/spring-3-1-m1-unified-property-management/
it introduce a new feature: user placeholder in import tag.
example: <import resource="com/bank/service/${customer}-config.xml"/>
well, I'm 3.1 too.
and then, when i start MYAPP, the miracle did not happen..
here is my code:
(config.properties in sourceFolder):
kName = P0765
(spring's xml):
<bean id="placeholderConfig" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">;
<property name="location" value="classpath:config.properties" >;
</bean>
<import resource="readyData/${KName}.xml"/>
:(
What work did not do??

Properties that are resolved in the import element have to be set as a JVM system property or system environment variable. It is described in the blog post you linked here.
This is because merging Spring configuration files happens before initializing beans (PropertyPlaceholderConfigurer is a bean) at it probably won't change, see this rejected feature request https://jira.springsource.org/browse/SPR-1358

Related

Cannot export Interface in OSGI

I am trying to export an interface (ITestRunable) I am sure I have linked everything correctly in the context.xml and osgi.xml files but it just wont work. The error is:
Application context initialization for 'me.overlaymanagement' has timed out waiting for (objectClass=me.overlaymanagement.testing.ITestRunable)
Any got any idea?
Code: Spring files for ITestRunable
context.xml
<bean id="testingRunable" class="me.overlaymanagement.testing.Testing"
init-method="startUp" destroy-method="shutDown">
</bean>
osgi.xml
<osgi:service id="testingRunable" ref="testingRunable">
<osgi:interfaces>
<value>me.overlaymanagement.testing.ITestRunable</value>
</osgi:interfaces>
</osgi:service>
Spring files for import into main system
context.xml
<bean id="overlaymanagementsystem"
class="me.overlaymanagementsystem.OverlayManagementSystem"
init-method="startUp" destroy-method="shutDown">
<property name="testingRunable" ref="testingRunable"/>
</bean>
osgi.xml
<osgi:reference id="testingRunable" cardinality="1..1"
interface="me.overlaymanagement.testing.ITestRunable">
</osgi:reference>
Gettors and Settors for ITestRunable within main system
public class OverlayManagementSystem{
...
protected ITestRunable testingRunable;
....
public ITestRunable getTestRunable() {
return testingRunable;
}
public void setTestRunable(ITestRunable testingRunable) {
this.testingRunable = testingRunable;
}
}
can anyone see a problem?
Ok so i managed to find the poblem. It was two things actually:
It didnt like that i had set the bean id and the service id where the ITestRunable code is located. Once i changed the service id name to something different it gave me a new error about invalid gettors and settors, which is the next point.
after some research i found the your gettor and setter for the imported service must be that same as the beans property name for that service. notice in my bean its:
< property name="testingRunable" .../>
and the get/set are defined as: "getTestRunable/setTestRunable". Changing these to getTestingRunable and setTestingRunable solved the problem for me.
I hope this helps others.

Spring reference a property from a property bean

I have created a spring configuration file that works well.
My next step was to separate user configuration properties from system properties.
I have decided to create additional xml file with beans that will be configured by the user.
I had problem to create few such logical beans encapsulating properties that will be used by real class beans:
I have found over the net an option to reference proprieties in such way:
UserConf.xml
<bean id="numberGuess" class="x...">
<property name="randomNumber" value="5"/>
<!-- other properties -->
</bean>
SystemConf.xml
<import resource="UserConf.xml" />
<bean id="shapeGuess" class="y...">
<property name="initialShapeSeed" value="#{ numberGuess.randomNumber }"/>
<!-- other properties -->
</bean>
But my problem is that i need x... class to be something logical that shouldn't be initialized at all, and i don't want it to disclose any info of the class hierarchy of the system since it should be only in use configuration xml file.
Solution1 is to create a Java object representing this proprieties:
public class MyProps(...)
and add a bean parent in the spring system configuration:
<bean id="MyProps" class="path to MyProps"/>
in the user side change the previous bean to be:
<bean id="numberGuess" parent="MyProps">
<property name="randomNumber" value="5"/>
<!-- other properties -->
</bean>
Solution2 is to use flat configuration file just like Database.props, and load it using factory.
Solution3 is to use Spring Property Placeholder configuration to load properties from XML properties file (e.g. example), but here i simply don't know how to get a more complex nested structure of properties (properties need to be separated by different logical names, e.g. minNumber will be defined both under xAlgo and y algo).
I don't like to create new Java class only to deal with this problem or to move my user configuration to a flat props file (i need the xml structure), is their any other solution??
I will answer my own question, since it looks as the best solution for me (and much more simplistic than was suggested)
I will use PropertiesFactoryBean to do the work for me:
e.g.
UserConf.xml
<bean id="numberGuess" class="org.springframework.beans.factory.config.PropertiesFactoryBean">
<property name="properties">
<props>
<prop key="randomNumber">3</prop>
<!-- other properties -->
</bean>
SystemConf.xml
<import resource="UserConf.xml" />
<bean id="shapeGuess" class="y...">
<property name="initialShapeSeed" value="#{ numberGuess.randomNumber }"/>
<!-- other properties -->
</bean>
First if you don't know about the property place holder you should take a look at that. Also #Value("${some.property:defaultvalue}") is something you should look at.
Second the word configuration is ambiguous in Spring. Spring uses this word but they mean developer configuration not user configuration. Despite what people say or think Spring is not a configuration engine.
I'm not sure what your trying to do but you should be aware that your configuration will not be adjusted at runtime which is frequently needed for something like "user" configuration. So most people write their own configuration layer.
Another thing you should take a look at is not using the XML configuration and instead use Java Configuration which will give you way more flexibility.

Set prefix for imported Spring XML resources

I have a Spring application context file that imports several other resources. However some of the resources in the imported files have similar names for example include1.xml has something like
<bean id="MyBean" class="...">
...
</bean>
The same bean id is used in include2.xml. Is there a way to set a prefix to the included beans or is there a way so restrict the scope of the included resource. For example something like.
<import resource="include1.xml" prefix="foo"/>
<import resource="include2.xml" prefix="bar"/>
Now in the parent file I can refer to foo.MyBean and bar.MyBean. If no such system exists is there any way to restrict scope so there is no bean id collisions, what is the best practice here?
No, there is no way to namespace the beans based on a file(beans defined later with the same name will override the one's defined earlier) however, you have the freedom to give them your own "name" - so potentially you can name all beans in your foo file:
<bean name="foo.bean1" class=../>
<bean name="foo.bean2" class=../>
and in your bar file, thus namespacing them manually:
<bean name="bar.bean1" class=../>
<bean name="bar.bean2" class=../>

Reusing bean definitions in Spring

Our project has two application contexts:
application-context.xml
application-context-test.xml
Currently each file has duplicate bean definitions. So for example the following bean would be in each application context:
<bean id="foo "class="com.foo">
<property name="bar">
<ref local="bar"/>
</property>
</bean>
The plan is to create another file for bean definitions so we can reuse the beans, however, if we put the above xml segment into its own file, there will be no reference to bar
Is there an easy way to solve this?
Please note that barwill be different in each application context.
Thanks!
<ref local="bar"/> has a specific meaning - it means that bar must be defined in the same file. In your case, that's too strict, so loosen it a bit:
<bean id="foo "class="com.foo">
<property name="bar" ref="bar"/>
</bean>
And then use <import resource="..."> to import this file where needed.
With this, bar must still exist, but it can be in any file that's part of the context, or in any of the parent contexts.
Sure, use a common context file that you import into both xml files.
<import resource="/common"/>
See 4.2.2.1. Composing XML-based configuration metadata

Import Spring config file based on property in .properties file

In my Spring xml configuration I'm trying to get something like this to work:
<beans>
<import resource="${file.to.import}" />
<!-- Other bean definitions -->
</beans>
I want to decide which file to import based on a property in a properties file.
I know that I can use a System property, but I can't add a property to the JVM at startup.
Note: The PropertyPlaceHolderConfigurer will not work. Imports are resolved before any BeanFactoryPostProcessors are run. The import element can only resolve System.properties.
Does anyone have a simple solution to this? I don't want to start subclassing framework classes and so on...
Thanks
This is, unfortunately, a lot harder than it should be. In my application I accomplished this by doing the following:
A small, "bootstrap" context that is responsible for loading a PropertyPlaceholderConfigurer bean and another bean that is responsible for bootstrapping the application context.
The 2nd bean mentioned above takes as input the "real" spring context files to load. I have my spring context files organized so that the configurable part is well known and in the same place. For example, I might have 3 config files: one.onpremise.xml, one.hosted.xml, one.multitenant.xml. The bean programmatically loads these context files into the current application context.
This works because the context files are specified as input the the bean responsible for loading them. It won't work if you just try to do an import, as you mentioned, but this has the same effect with slightly more work. The bootstrap class looks something like this:
public class Bootstrapper implements ApplicationContextAware, InitializingBean {
private WebApplicationContext context;
private String[] configLocations;
private String[] testConfigLocations;
private boolean loadTestConfigurations;
public void setConfigLocations(final String[] configLocations) {
this.configLocations = configLocations;
}
public void setTestConfigLocations(final String[] testConfigLocations) {
this.testConfigLocations = testConfigLocations;
}
public void setLoadTestConfigurations(final boolean loadTestConfigurations) {
this.loadTestConfigurations = loadTestConfigurations;
}
#Override
public void setApplicationContext(final ApplicationContext applicationContext) throws BeansException {
context = (WebApplicationContext) applicationContext;
}
#Override
public void afterPropertiesSet() throws Exception {
String[] configsToLoad = configLocations;
if (loadTestConfigurations) {
configsToLoad = new String[configLocations.length + testConfigLocations.length];
arraycopy(configLocations, 0, configsToLoad, 0, configLocations.length);
arraycopy(testConfigLocations, 0, configsToLoad, configLocations.length, testConfigLocations.length);
}
context.setConfigLocations(configsToLoad);
context.refresh();
}
}
Basically, get the application context, set its config locations, and tell it to refresh itself. This works perfectly in my application.
Hope this helps.
For the Spring 2.5 and 3.0, I have a similar solution to louis, however I've just read about 3.1's upcoming feature: property management, which sounds great too.
There is an old issue on the Spring JIRA for adding properties placeholder support for import (SPR-1358) that was resolved as "Won't Fix", but there has since been a proposed solution using an EagerPropertyPlaceholderConfigurer.
I've been lobbying to have SPR-1358 reopened, but no response so far. Perhaps if others added their use cases to the issue comments that would help raise awareness.
Why not:
read your properties file on startup
that will determine which Spring config to load
whichever Spring config is loaded sets specific stuff, then loads a common Spring config
so you're effectively inverting your current proposed solution.
Add something similar to the following:
<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="ignoreResourceNotFound"><value>true</value></property>
<property name="locations">
<list>
<value>classpath:propertyfile.properties</value>
</list>
</property>
</bean>
If what you want is to specify the imported XML file name outside applicationContext.xml so that you could replace applicationContext.xml without losing the configuration of the imported XML file path, you can just add an intermediate Spring beans XML file, say, confSelector.xml, so that applicationContext.xml imports confSelector.xml and confSelector.xml only contains an <import> element that refers to the suitable custom beans XML file.
Another means that might be of use are XML entities (defined by adding <!ENTITY ... > elements into the DTD declaration at the beginning of XML). These allow importing XML fragments from other files and provide "property placeholder"-like functionality for any XML file.
Neither of these solutions allows you to have the configuration file in Java's .properties format, though.
André Schuster's answer, which I bumped, helped me solve a very similar issue I was having in wanting to find a different expression of properties depending on whether I was running on my own host, by Jenkins on our build host or in "real" deployment. I did this:
<context:property-placeholder location="file:///etc/myplace/database.properties" />
followed later by
<bean id="propertyConfigurer"
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
<list>
<value>WEB-INF/classes/resources/database.properties</value>
...
</list>
</property>
</bean>
which solved my problem because on my development host, I put a link to my own copy of database.properties in /etc/myplace/database.properties, and a slightly different one on the server running Jenkins. In real deployment, no such file is found, so Spring falls back on the "real" one in resources in my class files subdirectory. If the properties in question have already been specified by the file on /etc/myplace/database.properties, then (fortunately) they aren't redefined by the local file.
Another workaround which does not rely on system properties is to load the properties of all the files using a different PropertyPlaceholderConfigurer for each file and define a different placeholderPrefix for each of them.
That placeholderprefix being configured by the initial property file.
Define the first property file: (containing either first or second)
global.properties
fileToUse=first
Define the files containing a property that can be switched depending on the property defined just above:
first.properties
aProperty=propertyContentOfFirst
second.properties
aProperty=propertyContentOfSecond
Then define the place holders for all the files:
<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
<list>
<value>classpath:global.properties</value>
</list>
</property>
</bean>
<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="placeholderPrefix" value="first{" />
<property name="locations">
<list>
<value>classpath:first.properties</value>
</list>
</property>
</bean>
<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="placeholderPrefix" value="second{" />
<property name="locations">
<list>
<value>classpath:second.properties</value>
</list>
</property>
</bean>
Use the property defined in global to identify the resource to use from the other file:
${fileToUse}{aProperty}
If I add the JVM argument below and have the file myApplicationContext.dev.xml, spring does load
-DmyEnvironment=dev
<context:property-placeholder />
<import resource="classpath:/resources/spring/myApplicationContext.${myEnvironment}.xml"/>
I'm using Spring 3 and load a properties like that:
<context:property-placeholder location="/WEB-INF/my.properties" />

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