How do I make use of #Value in the following 2 cases?
case 1: I have a PropertyPlaceholderConfigurer bean defined as follows
<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
<value>file:#{ systemProperties['user.home']}/myconf/settings.properties</value>
</property>
</bean>
Case 2: I did not define the bean, but i have declared property-place holder in the context as follows
<context:property-placeholder
location="file:#{ systemProperties['user.home']}/myconf/settings.properties" />
In both cases you would use like
#Value(value="${key.in.file}")
private String myVar;
Related
I want to get the changed key value from properties file at runtime.
test.properties file:
name = Hi
I have made Thread sleep with 5 sec and changed the key value as "Hello" but it is not getting changed.
<bean class="org.springframework.context.support.PropertySourcesPlaceholderConfigurer">
<property name="locations">
<list>
<value>classpath:test.properties</value>
</list>
</property>
<property name="ignoreResourceNotFound" value="true" />
<property name="ignoreUnresolvablePlaceholders" value="true" />
</bean>
<bean id="messageSource" class="org.springframework.context.support.ReloadableResourceBundleMessageSource">
<property name="basenames">
<list>
<value>classpath:test</value>
</list>
</property>
<property name="cacheSeconds" value="1" />
</bean>
<bean id="tempBean" name="tempBean1" class="org.sri.spring.temp.Temp"
lazy-init="false" scope="prototype">
<constructor-arg type="String" value="${name}" />
</bean>
The ${name} placeholder inside the XML configuration is resolved using the PropertySourcesPlaceholderConfigurer which, as you may notice, has nothing in common with your reloadable messageSource.
It wouldn't work either way because Spring instantiates the tempBean only once: on application startup, by passing the value of ${name} to the constructor. The bean itself is not aware of where the value came from (and in particular, it doesn't care if the properties file gets edited).
If you really think it's a good idea to do it†, you can inject the entire messageSource into your tempBean, and get the current value in each call, e.g.:
public class Temp {
#Autowired // or wired in XML, constructor, etc.
private MessageSource messages;
public String sayHello() {
return messages.getMessage("name", null, Locale.getDefault());
}
}
† injecting a configuration-related object makes testing more difficult and is arguably bad design (mixing concerns). Have a look at the Spring Cloud Config project as it's likely that this is how the future is going to look like.
I do not think that Spring will update already existing beans when the properties change.
Try to create a new bean (prototype scope)
I want to get specific value based on request from the property file.how to do that?
I have following spring configuration.i want to set the value for Exprops as per the request and get corresponding values from the properties file
<bean id="Prop" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="location">
<value>classpath:ErrorMessage.properties</value>
</property>
</bean>
<bean id="PropertiesBean" class="com.util.PropertiesUtil">
<property name="Exprops" value="${EXampleExceptiion}"></property>
</bean>
Use the PropertiesFactoryBean to inject the Properties in a Bean.
<bean id="myPropertiesBean"
class="org.springframework.beans.factory.config.PropertiesFactoryBean">
<property name="location" value="classpath:ErrorMessage.properties"/>
</bean>
This provides a Properties Object/Bean which can be injected under the name myPropertiesBean in any Bean (<property name="x" ref="myPropertiesBean"/>).
In addition Spring provides the util namespace (since Spring 2.5):
There you can write the PropertyFactoryBean definition a bit shorter:
<util:properties id="myPropertiesBean"
location="classpath:ErrorMessage.properties"/>
#see Spring Reference Chapter C.2.2.3.
All use the following for doing this programmatically
XmlBeanFactory factory = new XmlBeanFactory(new FileSystemResource("beans.xml"));
PropertyPlaceholderConfigurer cfg = new PropertyPlaceholderConfigurer();
cfg.setLocation(new FileSystemResource("jdbc.properties"));
cfg.postProcessBeanFactory(factory);
<util:properties id="" location="location of prop file" />
this return java.util.Properties object
I have the following configuration in my applicationContext.xml:
<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
<list>
<value>classpath:app.properties</value>
</list>
</property>
</bean>
Now, in my java class, how can I read the values from the file app.properties?
With Spring 3.0 you can use the #Value annotation.
#Component
class MyComponent {
#Value("${valueKey}")
private String valueFromPropertyFile;
}
Actually PropertyPlaceholderConfigurer is useful to inject values to spring context using properties.
Example XML context definition:
<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName"><value>${driver}</value></property>
<property name="url"><value>jdbc:${dbname}</value></property>
</bean>`
Example properties file:
driver=com.mysql.jdbc.Driver
dbname=mysql:mydb
Or you can create bean like
<bean name="myBean" value="${some.property.key}" />
and then inject this bean into your class
I have a string property which looks similar to the following example:
<property name="mappingData">
<list>
<bean class="com.company.product.longNamingStandard.migration.extractor.FieldMapping">
<property name="elementName" value="entitlement.user"/>
<property name="mapping" value="DocUsers"/>
</bean>
<bean class="com.company.product.longNamingStandard.migration.extractor.FieldMapping">
<property name="elementName" value="entitlement.contributor"/>
<property name="mapping" value="DocContributors"/>
</bean>
</list>
</property>
The long class name(s) effect readability & also create a refactoring overhead.
Is it possible to alias the class name and use a short name to declare the beans? Or is there an alternate best practice I'm missing?
Probably a bit late for you, but hopefully useful for others:
You can use parent beans to accomplish this.
First declare a parent bean as a template:
<bean id="FieldMapping" class="com.company.product.longNamingStandard.migration.extractor.FieldMapping"/>
Then use it elsewhere, using the parent attribute.
<property name="mappingData">
<list>
<bean parent="FieldMapping">
<property name="elementName" value="entitlement.user"/>
<property name="mapping" value="DocUsers"/>
</bean>
<bean parent="FieldMapping">
<property name="elementName" value="entitlement.contributor"/>
<property name="mapping" value="DocContributors"/>
</bean>
</list>
</property>
Please note my convention here is to use upper case id's here for the parent template beans.
each <bean/> comes with an attribute of name and id to help you reference those beans later in your configuration.
I would suggest using the id for declaring the bean.
your config could look like:
<bean id="fooBean" class="com.example.foo"/>
<bean id="barBean" class="com.example.bar"/>
<list>
<ref>fooBean</ref>
<ref>barBean</ref>
</list>
You may try to represent your mapping in some short form, and then convert it to the list of FieldMappings. For example, mappings from your snippet may be represented as a map.
As a theoretic exercise in Spring 3 you can do this with Spring Expression Language (if FieldMapping has the apropriate constructor):
<util:map id = "m">
<entry name = "entitlement.user" value = "DocUsers" />
<entry name = "entitlement.contributor" value = "DocContributors" />
</util:map>
...
<property name = "mappingData"
value = "#{m.![new com.company.product.longNamingStandard.migration.extractor.FieldMapping(key, value)]}" />
If this expression is too obscure, you may implement a FactoryBean to take a short form of your mapping data (for example, a map, as in this example) and return a configured list of FieldMappings:
<property name = "mappingData">
<bean class = "FieldMappingListFactoryBean">
<property name = "mappings">
<map>
<entry name = "entitlement.user" value = "DocUsers" />
<entry name = "entitlement.contributor" value = "DocContributors" />
</map>
</property>
</bean>
</property>
However, if your field mappings are some kind of reusable DSL, you may try to think about implementing a namespace extension.
I found a way to simulate an effect similar to a "import com.Foo;" in java code. The best option I could find was to use a PropertyPlaceholderConfigurer with local properties defined. Using your example, here's the configuration that you would put at the top of your spring config file to define a "class_FieldMapping" property:
<bean
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<description>Define properties equivalent to "import foo;" in java source</description>
<property name="properties">
<props>
<prop key="class_FieldMapping">com.company.product.longNamingStandard.migration.extractor.FieldMapping</prop>
</props>
</property>
</bean>
Then, you can use that property within your beans:
<property name="mappingData">
<list>
<bean class="${class_FieldMapping}">
...
</bean>
<bean class="${class_FieldMapping}">
...
</bean>
</list>
</property>
This has the benefit that use can also use it for things where you actually need the class name, and can't reference an instance of an object:
<util:constant static-field="${class_FieldMapping}.MYSTATICVAR" />
Why not declare those inner beans as separate top-level beans with their own names, and then reference them in the list ?
If I use PropertyPlaceholderConfigurer it leads to several exceptions in debug log. It works, but it seems it doesn't work on the first try.
I want to do something like the following in spring:
<beans>
...
<bean id="bean1" ... />
<bean id="bean2">
<property name="propName" value="bean1.foo" />
...
I would think that this would access the getFoo() method of bean1 and call the setPropName() method of bean2, but this doesn't seem to work.
What I understood:
You have a bean (bean1) with a
property called "foo"
You have another bean (bean2) with a
property named "propName", wich also
has to have the same "foo" that in
bean1.
why not doing this:
<beans>
...
<bean id="foo" class="foopackage.foo"/>
<bean id="bean1" class="foopackage.bean1">
<property name="foo" ref="foo"/>
</bean>
<bean id="bean2" class="foopackage.bean2">
<property name="propName" ref="foo"/>
</bean>
....
</beans>
Doing this, your bean2 is not coupled to bean1 like in your example. You can change bean1 and bean2 without affecting each other.
If you REALLY need to do the injection you proposed, you can use:
<util:property-path id="propName" path="bean1.foo"/>
You need to use PropertyPathFactoryBean:
<bean id="bean2" depends-on="bean1">
<property name="propName">
<bean class="org.springframework.beans.factory.config.PropertyPathFactoryBean">
<property name="targetBeanName" value="bean1"/>
<property name="propertyPath" value="foo"/>
</bean>
</property>
</bean>
I think you have to inject bean1, then get foo manually because of a timing issue. When does the framework resolve the value of the target bean?
You could create a pointer bean and configure that.
class SpringRef {
private String targetProperty;
private Object targetBean;
//getters/setters
public Object getValue() {
//resolve the value of the targetProperty on targetBean.
}
}
Common-BeanUtils should be helpful.