Setting property reference for a bean programmatically - spring

Right now i am using the following bean entry
<bean id="Service" >
<property name="target">
<bean class="someClass" lazy-init="false">
<property name="SessionFactory1"><ref bean="SessionFactory1"/></property>
<property name="SessionFactory2"><ref bean="SessionFactory2"/></property>
<property name="SessionFactory3"><ref bean="SessionFactory3"/></property>
</bean>
</property>
</bean>
Now the requirement is to first check which all session factories have an active datasource and include those only in the above bean definition. So that the application does not break if we try to initialize a session factory with inactive datasource.
sessionfactory initialization will be take care by using seperate config xml for session factories and loading only the ones with active datasources.
Please help on how can this be achieved.

You can use Spring InitializingBean interface, which makes you implement an afterPropertiesSet() method. This method will be executed after Spring instantiates your class, and you could check if your session factories are available or not.
InitializingBean: Interface to be implemented by beans that need to react once all their properties have been set by a BeanFactory: for example, to perform custom initialization, or merely to check that all mandatory properties have been set.
link: Spring InitializingBean

Related

spring batch: inject main application context #Component using AutomaticJobRegistrar

I'm trying to inject some #Service / #Repository bean defined in main application context into some jobs loaded by AutomaticJobRegistrar.
<bean class="org.springframework.batch.core.configuration.support.AutomaticJobRegistrar">
<property name="applicationContextFactories">
<bean class="org.springframework.batch.core.configuration.support.ClasspathXmlApplicationContextsFactoryBean">
<property name="resources" value="classpath*:/META-INF/jobs/*Job.xml" />
</bean>
</property>
<property name="jobLoader">
<bean class="org.springframework.batch.core.configuration.support.DefaultJobLoader">
<property name="jobRegistry" ref="jobRegistry" />
</bean>
</property>
</bean>
Using #Autowired inside my ItemWriter implementation class do not inject my services beans.
I have to enable component scanning inside each *Job.xml or declare each bean in order to make injection works, but injected classes are not the same instance of that one used by main application context.
How can I get the same instance bean declared in main application context?
Thank you for any advice
Did you activate context:annotation-config for each job?
If a new applicationcontext is created for every Job you need to activate this or no annotationprocessing (including #Autowired) will happen.
'context:component-scan' also activates 'context:annotation-config' so this might be the reason #Autowired works if you activate it.

When does spring use AOP without Aspectj.jar?

I can use annotation #Transactional at the top of my service PersonServiceBean and config transactionManager like below. After that, my service can execute db operations under transaction control through AOP.
<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
.........
</bean>
<tx:annotation-driven transaction-manager="txManager"/>
<bean id="personService" class="cn.itcast.service.impl.PersonServiceBean">
<property name="dataSource" ref="dataSource"/>
</bean>
But i didn't include aspectj.jar into my project. How does it work? I heard spring implements AOP through aspectj.
It doesn't use AspectJ by default, but uses proxies (either JDK interface proxies or CGLIB proxies). So, when you inject a transactional bean into another bean, what you get injected is in fact a proxy to your actual bean instance, which intercepts the method calls and starts/commits/rollbacks transactions.
More in the documentation, of course.

context:property-placeholder doesn't resolve references

I have next applicationContext.xml file on the root of classpath:
<context:annotation-config />
<context:property-placeholder location="classpath:props/datasource.properties" />
<bean id="datasource" class="org.apache.commons.dbcp.BasicDataSource"
p:username="${jdbc.username}"
p:password="${jdbc.password}"
p:url="${jdbc.url}"
p:driverClassName="${jdbc.driverclass}"
p:validationQuery="SELECT sysdate FROM dual" />
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"
p:dataSource-ref="datasource"
p:mapperLocations="classpath:mappers/*-mapper.xml" />
<tx:annotation-driven transaction-manager="txManager" />
<bean id="txManager"
class="org.springframework.jdbc.datasource.DataSourceTransactionManager"
p:dataSource-ref="datasource" />
<bean id="mappeScannerConfigurere" class="org.mybatis.spring.mapper.MapperScannerConfigurer"
p:sqlSessionFactory-ref="sqlSessionFactory"
p:basePackage="com.mypackage" />
props/datasource.properties also exists on the root of classpath with such content:
jdbc.url=myjdbcurl
jdbc.driverclass=myClass
jdbc.username=myUserName
jdbc.password=myPassword
I have a spring managed test where I declare to use previously mentioned applicationContext.xml via next annotations:
#RunWith(SpringJUnit4ClassRunner.class)
#ContextConfiguration(locations = {"classpath:applicationContext.xml"})
When I invoke test method i get next error from spring:
org.apache.commons.dbcp.SQLNestedException: Cannot load JDBC driver class '${jdbc.driverclass}'
As I understand sping didn't resolve reference to jdbc.driverclass.
What have I done wrong?
PS: I'm using spring 3.2.3.RELEASE
**
EDIT
**
Perhaps the problem may be in MapperScannerConfigurer. It is a BeanDefinitionRegistryPostProcessor and as Javadoc says:
Extension to the standard BeanFactoryPostProcessor SPI,
allowing for the registration of further bean definitions
before regular BeanFactoryPostProcessor detection kicks in
So MapperScannerConfigurer instantiates datasource object via sqlSessionFactory with BeanFacoryPostProcessor(which is responsible for <context:property-placeholder/>) have not been utilized.
So my question transforms to how to reorder BeanFacoryPostProcessor from <context:property-placeholder/> and BeanDefinitionRegistryPostProcessor(MapperScannerConfigurer)?
Resolved
After a couple hours of investigation I found the solution:
As I said earlier MapperScannerConfigurer is a BeanDefinitionRegistryPostProcessor which fires before BeanFactoryPostProcessor which is responsible for <context:property-placeholder/>. So, during the creation of MapperScannerConfigurer references to external properties will not be resolved. In this case we have to defer the creation of datasource to the time after BeanFactoryPostProcessorhave been applied. We can do that in several ways:
remove p:sqlSessionFactory-ref="sqlSessionFactory" from MapperScannerConfigurer. In this case datasource object will not be created before MapperScannerConfigurer, but after BeanFactoryPostProcessor which is responsible for <context:property-placeholder/>. If you have more than one sqlSessionFactory in applicationContext, than can be some troubles
In versions of mybatis-spring module higher than 1.0.2 there is a possibility to set sqlSessionFactoryBeanName instead of sqlSessionFactory. It helps to resolve PropertyPlaceHolder issue with BeanFactoryPostProcessor. It is a recommended way to solve this issue described in mybatis-spring doc
I was having the same issue and came across this post but I was unable to resolve it the same way maks did. What ended up working for me was to set the ignoreUnresolvablePlaceholders property value to true.
<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="location">
<value>classpath:database.properties</value>
</property>
<property name="ignoreUnresolvablePlaceholders" value="true"/>
</bean>
I am using Spring 3.2.3.RELEASE as well. I realize this post is over 4 months old but I figured someone might find it useful.
Short form: What is the proper way to load an implementation of: BeanDefinitionRegistryPostProcessor?
Expanded form: Is there a way to load BeanDefinitionRegistryPostProcessor before any beans have been created. If you look at the javadoc:
Extension to the standard {#link BeanFactoryPostProcessor} SPI, allowing for
the registration of further bean definitions before regular
BeanFactoryPostProcessor detection kicks in.
So it's meant to be loaded when bean definitions have been created but before any beans have been created. If we just create it as a regular bean in the application xml then it defeats the purpose of having this bean in the first place.

Configuring Datasource in Spring 3.0

Hello guys I have configured a connection pool and JNDI resource in glassfish 2.1. I can get the Datasource via lookup method in my projects and everything works good. However I decided to try Spring framework and to use my existing connection pool.
In the Spring context file I have the following:
<jee:jndi-lookup id="dataSource" jndi-name="jdbc/name" />
<bean id="jdbcTemplate" class="org.springframework.jdbc.core.simple.SimpleJdbcTemplate">
<constructor-arg ref="dataSource"/>
</bean>
<bean id="dao" class="com.mycompany.mavenproject3.Dao">
<property name="simpleJdbcTemplate" ref="jdbcTemplate"/>
</bean>
When I deploy the project I get:
java.lang.IllegalArgumentException: 'dataSource' or 'jdbcTemplate' is required]
Is there anything else I have to configure in that file or in any other file in order to get the Datasource?
Presumably, com.mycompany.mavenproject3.Dao extends JdbcDaoSupport, but you're setting a property named simpleJdbcTemplate on it, leading me to believe that you've defined your own property to hold the template since that doesn't exist on Spring's implementation. It's therefore complaining at you because you're required to set either the dataSource property or the jdbcTemplate property of the JdbcDaoSupport object before using it, exactly like it's telling you. Change <property name="simpleJdbcTemplate"... to <property name="jdbcTemplate"....
If your DAO doesn't extend JdbcDaoSupport, then find what does and remove it or set its properties appropriately.
You can also call your datasource directly in your dao bean, don't need to do an another bean for jdbcTemplate. So your context file become something like this:
<jee:jndi-lookup id="dataSource" jndi-name="jdbc/name" />
<bean id="dao" class="com.mycompany.mavenproject3.Dao">
<property name="dataSource" ref="dataSource"/>
</bean>
After you just have to extends JdbcDaoSupport spring class (in which contain the getter and setter of datasource) on your Dao class.

Spring El Expression

I'm switching from faces-config to Spring and wanted to know how you can pass a property from one bean to another:
e.g.
<bean id="myBean" class="Bean1">
</bean>
<bean id="myBean2" class="Bean2">
<constructor-arg ref="#{myBean1.value}"/>
</bean>
Upgraded to Spring 3.0 which has spring el support
First things first, the purpose of the D.I container is to fully initialize your system prior to execution; that is, all dependencies being set, the app is ready to run.
There are both #property and #value annotations in Spring for similar purposes, but since you want to use and specific bean property value for other bean the best solution would be:
<bean id="myBean" class="Bean1">
</bean>
<bean id="myBean2" class="Bean2">
<constructor-arg ref="myBean"/>
</bean>
If you argue that you just want to set the value at instantiation time, and not establish a dependency, then skip the D.I part and set the value directly.

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