We Keep Coding

Passing Spring Boot Property Bean to Classes in other Projects

I am configuring a spring boot application. So I created a property bean class like this:
import javax.validation.constraints.NotNull;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
#Configuration
#EnableConfigurationProperties
#PropertySource("classpath:/application.properties")
public class APPStaticProperties {
#NotNull
#Value("${dblog.system.name}")
String db_logsystem_name;
/**
* #return the db_logsystem_name
*/
public String getDb_logsystem_name() {
return db_logsystem_name;
}
/**
* #param db_logsystem_name the db_logsystem_name to set
*/
public void setDb_logsystem_name(String db_logsystem_name) {
this.db_logsystem_name = db_logsystem_name;
}
}
And I am creating a object by in the controller class:
#Autowired
APPStaticProperties appStaticProperties;
But I wanted to know how do I pass the this object for use in other projects? Because my code flow goes from the controller to a JSP and then to a class in another project. I need the object available for use in that class. Well to be honest, in many other projects as well! I am not able to figure it out how to do it. Neither are there too many examples out there for reference.

You wouldn't normally inject an #Configuration bean into other Spring managed beans, because it sets up configuration to be used by other Spring managed beans.
For example, because you have declared an #PropertySource, to access your properties in other Spring managed means you can just inject properties into your code elsewhere using #Value. You don't need to inject your APPStaticProperties bean to do this.

Camel read properties file

How do I configure the use of a properties file using Java DSL and the Main object?
According to this page I should be able to call something like:
main.setPropertyPlaceholderLocations("example.properties");
However that simply doesn't work. It seems that option wasn't added until Camel 2.18 and I'm running 2.17.1.
What was the original way to set a properties file to use when letting the application run in a standalone form?
Some backstory:
I'm trying to convert from Spring to Java DSL. During that conversion I was attempting to have my Camel application run on its own. I know that is achieved using main.run();.
I had things "functioning" when using the CamelContext, but that cannot run on its own. So I know using the following will work in that case:
PropertiesComponent pc = new PropertiesComponent();
pc.setLocation("classpath:/myProperties.properties");
context.addComponent("properties", pc);
Is there some way I can tell the main to use that setup? Or is there something else needed?

You can use the following snippet:
PropertiesComponent pc = new PropertiesComponent();
pc.setLocation("classpath:/myProperties.properties");
main.getCamelContexts().get(0).addComponent("properties", pc);
Also, if you are using camel-spring, you could use org.apache.camel.spring.Main class, it should use the property placeholder from your application context.

Since you are mentioning you are in the process to move from Spring XML to Java Config here's a minimum application that is using properties and injecting it into a Camel route (it's really properties management in Spring injected into our Camel route bean):
my.properties:
something=hey!
Main class:
package camelspringjavaconfig;
import org.apache.camel.spring.javaconfig.CamelConfiguration;
import org.apache.camel.spring.javaconfig.Main;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
#Configuration
#ComponentScan("camelspringjavaconfig")
#PropertySource("classpath:my.properties")
public class MyApplication extends CamelConfiguration {
public static void main(String... args) throws Exception {
Main main = new Main();
main.setConfigClass(MyApplication.class); // <-- passing to the Camel Main the class serving as our #Configuration context
main.run(); // <-- never teminates
}
}
MyRoute class:
package camelspringjavaconfig;
import org.apache.camel.builder.RouteBuilder;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.env.Environment;
import org.springframework.stereotype.Component;
#Component
public class MyRoute extends RouteBuilder {
#Autowired
Environment env; //<-- we are wiring the Spring Env
#Override
public void configure() throws Exception {
System.out.println(env.getProperty("something")); //<-- so that we can extract our property
from("file://target/inbox")
.to("file://target/outbox");
}
}

Spring #Autowired not working for eagerly initialized beans

I am trying to write a service-oriented application.
I have a been called memory defined as such:
package com.example.assets;
//imports ignored
#Resource
public class Memory {
}
And I have a service been called memoryHandler defined as such:
package com.example.service;
//imports ignored
#Service
public class MemoryHandler {
#Autowired
private Memory memory;
public void execute() {
//do something with memory
}
}
There is also another class, which is a BeanFactoryPostProcessor:
package com.example.service;
//imports ignored
#Component
public class PostProcessor implements BeanFactoryPostProcessor {
#Override
public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
beanFactory.getBeansOfType(MemoryHandler.class, false, true);
}
}
Which prematurely looks up the bean, memoryHandler, leaving it instantiated` but not autowired. However, I want the bean to be autowired before it is fetched by the factory.
In my Main class I have written:
package com.example.service;
//imports ignored
public class Main {
public static void main(String[] args) {
final ApplicationContext context = new ClassPathXmlApplicationContext("/context.xml");
context.getBean(MemoryHandler.class).execute();
}
}
I get a NullPointerException on the line I work with the memory. I replaced the above declaration with a setter injection, and upon tracing realized that the injection never occurs.
I have changed the annotations on both components to Service, Repository, and Component and also have tried replacing Autowired with Resource to no avail.
What am I missing here? I have read all the questions that have shown up in my search for an answer, and none of them helps me (I got the tip about using Resouce annotations there).
Needless to say, I have not missed annotation configuration for my beans:
<context:annotation-config/>
<context:component-scan base-package="com.example"/>
Moreover, autowiring works just fine when autowired beans are defined in the XML configuration file, and not via annotations.
I am using Spring 3.2.3.RELEASE.

Changing the implementation of the PostProcessor is the key:
Instead of:
public class PostProcessor implements BeanFactoryPostProcessor {
I will have to write:
public class PostProcessor implements ApplicationContextAware {
This ensures that the context will be fully populated before it is post-processed, which in my case works just fine. But I am wondering if there is another way to do this, using the usual BeanFactoryPostProcessor interface?

Spring Dependency Injection using Java Container Configuration

I'm new to Java and Spring, coming from C# and the .NET world, so bear with me - what I am attempting to do may be off the mark...
I am attempting to configure Spring DI using Java configuration and annotations, not XML configuration, however I am having a few issues. This is for a standalone application, not a web app. I have worked through the springsource documentationand as far as I can tell my very basic configuration should be correct...but isn't. Please take a look at the code below:
Java Configuration Annotated Class:
package birdalerter.common;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import birdalerter.process.ISightingsProcessor;
import birdalerter.process.SightingsProcessor;
#Configuration
#ComponentScan({"birdalerter.process", "birdalerter.common"})
public class AppConfig {
#Bean
#Scope("prototype")
public ISightingsProcessor sightingsProcessor(){
return new SightingsProcessor();
}
}
Configure Component implementing the ISightingsProcessor interface:
package birdalerter.process;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.LinkedBlockingQueue;
import org.springframework.stereotype.Component;
import birdalerter.domainobjects.IBirdSighting;
#Component
public class SightingsProcessor implements ISightingsProcessor{
private LinkedBlockingQueue<IBirdSighting> queue;
private List<ISightingVisitor> sightingVisitors = new ArrayList<ISightingVisitor>();
public SightingsProcessor(){
}
...
}
Configure Factory Component:
package birdalerter.process;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Required;
import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Component;
#Component
public class ProcessorFactory {
private ISightingsProcessor sightingsProcessor;
#Autowired
#Required
private void setSightingsProcessor(ISightingsProcessor sightingsProcessor){
this.sightingsProcessor = sightingsProcessor;
}
public ISightingsProcessor getSightingsProcessor(){
return this.sightingsProcessor;
}
}
Wire up the AnnotationConfigApplicationContext and test:
#Test
public void testProcessingDI(){
#SuppressWarnings("resource")
AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
context.register(AppConfig.class);
context.refresh();
ISightingsProcessor processor = new ProcessorFactory().getSightingsProcessor();
System.out.println(processor);
Assert.assertTrue(processor != null);
}
The SightingsProcessor is not being setter injected and the assert is failing as the returned object is null. Hopefully I have missed something very obvious.
Thanks in advance.
Edited in Response to Meriton:
Thanks for the answer Meriton.
Why would Spring not know about the newly created object? Does Spring not maintain dependencies throughout the application lifecycle and inject as appropriate when new objects are created that are configured as beans?
I don't want to directly use context.getBean(ISightingsProcessor.class) if I can help it to be honest, I would like the dependency injected in the setter method without having manual intervention - it just seems cleaner.
I am using the ProcessorFactory as the ISightingsProcessor interface extends Runnable - the implementing object is to be started as a thread. The application will be configurable to have n* threads, with each being started within a loop iteration. I don't think it is possible (I may be wrong, please advise if so) to have #Autowired annotations within method declarations, hence I use the factory to supply a new instance of the injected ISightingsProcessor concrete class.
Yes I've just had a look regarding the #Scope annotation - you are right, that needs moving to the AppConfig #Bean declaration (which I've done in this edit), thanks for that.

ISightingsProcessor processor = new ProcessorFactory().getSightingsProcessor();
This calls the constructor of ProcessorFactory, and then the getter of the instance the constructor created. Spring can not know about that newly created object, and therefore not inject its dependencies. You should ask Spring for the ProcessorFactory instead, for instance with
ProcessorFactory pf = context.getBean(ProcessorFactory.class);
ISightingsProcessor processor = pf.getSightingsProcessor();
That said, I don't know why you need class ProcessorFactory at all. You might just as well get the ISightingsProcessor directly:
ISightingsProcessor processor = context.getBean(ISightingsProcessor.class);
Additionally, "Java Based Configuration" and component scanning are independent ways to declare beans. Currently, you are therefore declaring the ISightingsProcessor twice: Once with the #Bean-annotated factory method, and once with the component scan and the #Component annotation on the class. Doing either of that will do. In fact, doing both might cause one bean definition to override the other.
Oh, and the #Scope annotation is for bean definitions (those you annotate with #Bean or #Component). It will likely be ignored on injection points (#Autowired).

Is there an annotations based method for getting springs application context?

I was wondering is there an annotations based method for starting a spring application?
i.e. replacing this below:
public static void main(String[] args) {
ApplicationContext ctx = new ClassPathXmlApplicationContext("spring.xml");
User user = (User)ctx.getBean("user");
user.createUser();
}
With an annotations based method for getting the context and then Autowiring in the bean?

I don't think you can do that, after all someone would have to understand and process that annotation. If Spring has not initialized yet, who would?

There is an anotation in spring: called #ContextConfiguration
Very helpfull for testing.
You need to extend one of the spring abstract classes created for test support(testNG or JUnit).
(e.g. AbstractTransactionalTestNGSpringContextTests tor testNG or AbstractTransactionalJUnit4SpringContextTests for JUnit)
Then you just use the #ContextConfiguration annotation(for Class, interface (including annotation type), or enum declaration)
some example code for junit test:
#RunWith(SpringJUnit4ClassRunner.class)
// ApplicationContext will be loaded from "/applicationContext.xml" and "/applicationContext-test.xml"
// in the root of the classpath
#ContextConfiguration(locations={"/applicationContext.xml", "/applicationContext-test.xml"})
public class MyTest {
// class body...
}
please read:
http://static.springsource.org/spring/docs/2.5.x/reference/testing.html

You cannot avoid that ClassPathApplicationContextXml code but you can avoid that ctx.getBean("user") by doing as below. Ideally what it does is it asks the xml to scan the packages where spring want to inject things. The only thing you should not here is that i have declared my main class as spring Component, since springs annotations work on spring recognized classes and hence i am making my main as spring recognized class. The loading of xml using Classpathapplicationcontext cannot be avoided.
package com.spring.sample;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.stereotype.Component;
import com.spring.sample.component.Sample;
#Component
public class SampleMain {
#Autowired
Sample testSample;
static ApplicationContext appCtx = new ClassPathXmlApplicationContext("META-INF/webmvc-application.xml");
public static void main(String[] args){
SampleMain sampleMain = appCtx.getBean(SampleMain.class);
sampleMain.invokeSample();
}
private void invokeSample(){
testSample.invokeSample();
}
}