I want to understand how the annotation works. I have this piece of code which I have used in a simple Spring project.
#Resource(name="dataSource")
private DataSource dataSouce;
The dataSource I have defined in an XML config file:
<!-- The Apache DBCP implementation of DataSource -->
<bean id="dataSource" class="org.apache.commons.dbcp2.BasicDataSource">
<property name="driverClassName" value="org.h2.Driver"/>
<property name="url" value="jdbc:h2:tcp://localhost/~/test"/>
<property name="username" value="sa"/>
<property name="password" value=""/>
</bean>
Other snippet from spring xml config file
<context:annotation-config /> <!-- This enables the annotation's actions, else annotations don't do their work. -->
<context:component-scan base-package="com.example.dao.jdbc.impl"/> <!-- This is for component scan -->
<bean id="jdbcOperImpl" class="com.example.dao.jdbc.impl.JdbcOperImpl"/>
As I understand the Resource annotations comes from javax.annotation.Resource. I looked its source code, and I notices the annotation is defined by JDK SE, and it is just a simple definition of an annotation. How does this do the injection? Does Spring Framework use this annotation and does Injection? How is #Resource annotation and Spring framework related?
Actually Spring supports two types of annotations which are Spring based annotations and Java based annotations. For dependencies you can use #Autowired that completely spring annotations.
#Resource and #Inject are the standard java based annotations. For more clarity see this link http://blogs.sourceallies.com/2011/08/spring-injection-with-resource-and-autowired/
Related
I created a JSF Application and I'm not sure what I should put into the faces-config?
One of my ManagedBeans looks like the following:
#ManagedBean(name = "ProfileBean")
#ViewScoped
public class ProfileBean implements Serializable
my applicationcontext
<context:annotation-config />
<bean class="org.springframework.context.annotation.CommonAnnotationBeanPostProcessor" />
<bean id="QuestionDao" class="code.elephant.dao.QuestionDao"></bean>
<bean id="QuestionService" class="code.elephant.service.QuestionService">
<constructor-arg ref="QuestionDao"/>
</bean>
<bean id="QuestionBean" class="controller.QuestionBean">
<constructor-arg ref="QuestionService"/>
</bean>
<bean id="UserDao" class="code.elephant.dao.UserDao"></bean>
<bean id="UserService" class="code.elephant.service.UserService">
<constructor-arg ref="UserDao"/>
</bean>
<bean id="LoginBean" class="controller.LoginBean">
<constructor-arg ref="UserService"/>
</bean>
<bean id="ProfileBean" class="controller.ProfileBean">
<constructor-arg ref="UserService" />
<property name="_LoginBean" ref="LoginBean"></property>
</bean>
my faces-config
<application>
<el-resolver>org.springframework.web.jsf.el.SpringBeanFacesELResolver</el-resolver>
</application>
I saw some examples which defines <managed-beans> in the java-faces.config but I already used the #ManagedBean annotation in the java class. Is this rly necessary? Is my setup up with jsf spring correct? Should I also define the managed beans in the faces-config?
The purpose of the SpringBeanFacesELResolver that you have configured in faces-config is to make it so that you can use Spring beans instead of the old-style JSF managed beans or CDI dependency injection.
Remove the #ManagedBean annotation from your ProfileBean class. You don't need it since you are using Spring instead of JSF's old managed beans mechanism.
The #ManagedBean annotation is a remnant from old versions of JSF; don't use it if you are using a newer version of JSF. Current versions of JSF use CDI (the standard Java EE API for dependency injection), but you are using Spring instead, so you should configure your beans the Spring way (which you are already doing since you've defined ProfileBean in your Spring XML config).
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.
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.
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.
I want to have some alternative to this using Spring DSL in Grails.
<bean name="someName" class="SomeClass">
<property name="resource" value="classpath*:Queues.xml"></property>
</bean>
If you really want to, you can use resources.xml instead of resources.groovy for a more conventionally Spring-y style.