Can I start with a spring boot application without the annotations componentscan,autoconfiguration,configuration,springbootapplication? - spring

I have written some code in order test integration with mongoDB. Please find the link to the main method for running this spring boot application below,
https://github.com/siva54/simpleusercontrol/blob/master/src/main/java/com/siva/UserManagementApplication.java
From what I have read, An application should contain any of the configurations from the following URL to declare how the applications manages the context,
http://docs.spring.io/autorepo/docs/spring-boot/current/reference/html/using-boot-using-springbootapplication-annotation.html
I haven't used any of those contexts, However my application works fine and I'm able to run it without any issues. Am I missing something here? Can you please help with the info of how my application is able to start and manage the context/dependencies automatically?
Thanks in advance

#SpringBootApplication is equivalent of #Configuration, #EnableAutoConfiguration and #ComponentScan. Let's consider why your application works without of any of this three annotations.
Why it works without #Configuration:
When Spring will scan packages, it will find all classes marked by #Configuration and will use them as part of configuration. But in next line you manually passed UserManagementApplication as configuration source:
SpringApplication.run(UserManagementApplication.class, args);
So spring doesn't need to find this class by scan. Therefor it is not necessary to mark it by #Configuration.
Why it works without #ComponentScan:
Class UserManagementApplication has #ImportResource("classpath:spring/application-context.xml") annotation. That means file spring/application-context.xml will be included into configuration. And this file contains next line:
<context:component-scan base-package="com.siva.*" />
So, you don't need use annotation for scan packages, because you already declared it in the xml file.
Why it works without #EnableAutoConfiguration:
This annotation allows to Spring to try guess and configure the components automatically. For example, if you include the following dependency in your build.gradle:
dependencies {
compile 'org.springframework.boot:spring-boot-starter-data-mongodb'
}
Spring configures all the components required to work with MongoDB automatically. And all you need just specify host and user/pass in the aplication.proprties file.
But you preferred to declare all needed beans manually in the spring/application-context.xml file. So, you simply don't need #EnableAutoConfiguration annotation at all.

Related

Run Mongock before #Configuration annotated class

I want to use Mongock migration tool to initialize my app's configuration that is stored in database.
The problem I have is that one of my configs is used in class that is annotated with #Configuration. As Mongock changesets are executed after #Configuration it cannot retrieve not existing yet value from database and that results in a crash of application. Is there a way to postpone creating #Configuration class? Or should I initialize this one config without using mongock?
I don't fully understand your issue. I think that you need Mongock to run before your class annotated with #Configuration is processed. As you mention, SpringMongock requires the configuration class to be processed, as it requires the Spring ApplicationContext. However, you can run Mongock as standalone runner and use it(run it) wherever you want, as it doesn't depend on Spring context.
Mongock documentation
I hope it helps.

Springboot build not working because of test configuration

I have started a spring boot project using start.spring.io.
But I am getting this error-
I have read various articles on the internet about this issue and they all say about putting my tests in the same package as my Main class.
But I already have the same.
Could you point out what is wrong with my configuration?
The exception is pretty clear: You are missing a configuration for your spring context. What you need to do is to add the configuration classes for your context like so:
#SpringBootTest(classes = { TestConfiguration.class })
whereas your TestConfiguration class must be annotated with
#Configuration
and/or
#EnableAutoConfiguration
There you can add configurations to your liking. You can of course also use your DatabaseApplication class as Configuration although Im wouldn't recommend that.
The search algorithm works up from the package that contains the test until it finds a #SpringBootApplication or #SpringBootConfiguration annotated class. As long as you’ve structure your code in a sensible way your main configuration is usually found.
Make Sure your DatabaseApplication class is annotated with #SpringBootApplication .

Spring AOP aspect doesn't get applied if included from an external jar with different package name

I have a spring boot rest service that included an external project in pom as it's dependency. That external project is basically a jar that has spring AOP code.
The base package in my main application that includes this external jar with spring AOP code is x.y.z
The class in external jar where the #before advice is, is under the package a.b.c
With this class under a.b.c package, it doesn't get recognized by the main application where I want to use the spring aop implementation and apply the aspect. However, when I change it's package from a.b.c to x.y.z (which I really can't do in real life) it works fine.
I know that in spring boot service which happens to be the including service, it scans everything under root package given in the application class, x.y.z in this case and that is why aspect works fine if it's class is under x.y.z.
however, the problem is that this spring app jar will be used across multiple applications. So changing package name like this is not an option.
Is there a way to accomplish this without changing the package name of the class where spring app code is ?
Probably component scan is only activated for your application class packages by default. You can extend it to multiple packages, including the aspect package:
XML style configuration:
<context:component-scan base-package="x.y.z, a.b.c" />
Annotation style configuration:
#ComponentScan(basePackages = {"x.y.z", "a.b.c"})
Disclaimer: I am not a Spring user, only an AspectJ expert. I just knew that you can configure component scan, googled the syntax for you and hope it is correct.
Please define the bean (of jar project )inside main application. Give the #ComponentScan(basePackages = {"x.y.z", "a.b.c"}) as well as #EnableAspectJAutoProxy. Also include below piece of code.
ex:
` #Bean
public LoggingHandler loggingHandler()
{
return new LoggingHandler();
}`
Also annotate external jar code with:
`#Aspect
#Component
public class LoggingHandler {`
What #kriegaex suggests is correct. In addition to that, please make sure you are using #Component along with #Aspect. Since #Aspect is not a Spring annotation, Spring won't recognize it and hence your aspect won't be registered. So, using #Component is mandatory to getting aspects to work in Spring environment.

Wiring a bean from dependency module

I have created a configuration project which essentially creates couple of beans with configuration stereotype. Then, I want this project to be reused across by my clients.
I have added this config project as a maven dependency, but my client project is not having those beans i have created as part of configuration project.
Could someone help
Ok, the answer is the following: you should place
#ComponentScan("you.configurations.base.package")
on one of your configuration (in the current application, one that #SpringBootApplication sees) or on the class with #SpringBootApplication annotation.
The explanation is as follows: #SpringBootApplication under the hood contains #ComponentScan without specifying a base package. That means that it says to Spring to scan the package where the class annotated with #SpringBootApplication resides and all the packages recursively. And that's it. If you place you #Configuration somewhere there - it will create it during startup, otherwise not.
We can resolve this by enabling spring-boot autoconfiguration
Create classpath->resources->META-INF->spring.factories file
org.springframework.boot.autoconfigure.EnableAutoConfiguration=[add your class with you need to be loaded during application load time]

spring-boot without #SpringBootApplication

I am attempting to migrate a spring, non-boot, app to a boot app. The current one builds a war file. Following these instructions, I am walking through the steps to migrate.
I am finding that the #SpringBootApplication annotation forces a lot of things to fail. For instance, it tries to auto config security when I really need the existing xml security config to remain as is. I found that I can override #EnableAutoConfiguration and exclude configuration classes (.i.e. SecurityAutoConfiguration.class). But I am finding it is doing this a great deal for the items I already have on my classpath. I decided it would be better to remove #SpringBootApplication and replace it with just #Configuration, #ComponentScan and #ImportResource to load my original context xml. The class extends SpringBootServletInitializer so that I can register my custom servlets and filters.
What I have found, it now no longer knows to load the application.yml or bootstrap.yml. What triggers auto configuration of these files? Do I fall back to loading with the traditional properties placeholder configurers? I want to avoid this as the next step is to hook it up to spring cloud config to centralize the management of the application configuration.
#SpringBootApplication is a alternative for #Configuration, #EnableAutoConfiguration and #ComponentScan.
Probably you want use #Configuration + #ComponentScan. If you want load xml configuration you can use: #ImportResource annotation.
If you want use autoconfiguration, but you can disable a few auto configurations, eg:
#EnableAutoConfiguration(exclude={DataSourceAutoConfiguration.class})
Details:
http://docs.spring.io/spring-boot/docs/current/reference/html/using-boot-auto-configuration.html
http://docs.spring.io/spring-boot/docs/current/reference/html/using-boot-configuration-classes.html
http://docs.spring.io/spring-boot/docs/current/reference/html/using-boot-using-springbootapplication-annotation.html

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