Develop Reference

Hibernate/Spring framework: path of the database in a configuration file

I am trying to write a simple Hibernate application and I want the SQLite database location to be changed according to an application configuration file.
What I was trying to do was therefore retrieving the path of the database from a text file in the project and putting it inside dbLocation, then running the following piece of code:
Configuration config = new Configuration();
config.setProperty("hibernate.connection.url", "jdbc:sqlite:" + dbLocation);
Is there a better and more "standard" way to do so? I'm using Spring Boot for my application and I just realized there's afile called application.properties. May I use this one maybe? I'm pretty new to both Hibernate and the Spring framework.

In Spring Boot application properties you can externalize your application properties so they are configured/managed outside your application source code.
Once a property is defined in application.properties you can use SpringBoot built-in feature to access the values
#Configuration
public class ApplicationProperty {
#Value("${prop}")
private String prop;

With Spring Boot another way is to use #ConfigurationProperties.
Example from the documentation can be found here
A comparison between #ConfigurationProperties and #Value annotation from the documentation
Feature #ConfigurationProperties #Value
Relaxed binding Yes No
Meta-data support Yes No
SpEL evaluation No Yes

Adding a conditional external PropertySource in a spring boot application

I'm currently using an EnvironmentPostProcessor to add my external PropertySource, the code looks like this :
public class ExternalPropertySourceEnvironmentPostProcessor implements EnvironmentPostProcessor
{
private static final String EXTERNAL_PROPERTY_SOURCE_NAME = "ExternalPropertySource";
#Override
public void postProcessEnvironment(ConfigurableEnvironment environment, SpringApplication application)
{
if (environment.acceptsProfiles(Profiles.EXTERNAL_PROPERTY_SOURCE_ENABLED_PROFILE)) {
environment.getPropertySources()
.addLast(new ExternalPropertySource(EXTERNAL_PROPERTY_SOURCE_NAME, new ExternalSource()));
}
}
}
A spring.factories is also used to register this EnvironmentPostProcessor.
This code actually works if the profile is set in the vm environment variables, but if it is added in src/main/resources/application.yml, the profile doesn't seem to be injected yet in the environment and is not returned by the environment.getActiveProfiles(). I've tried using the interface Ordered with the lowest precedence, but it doesn't help.
To add a bit of context around what I'm trying to achieve, this class is in a small library that adds an external property source like a database. Then we can use it in some other spring boot applications. Something like Spring Cloud Config does.
I'd like a clean way to enable or disable this property source depending on the environment where the code runs. I don't mind using something else then profiles or even another way to inject the property source, I just want something clean that doesn't depend on several factors to work.
The main problem in my code right now is that I'm using spring boot's property sources to make my own property source configurable.
UPDATE : I used a Spring Cloud app to debug this, and was confusing the bootstrap context with the normal spring boot context. See my answer below.

Further investigation made me figure out the problem appeared only with a Spring Cloud application.
In fact the breakpoint I had in this code was triggered twice, once after the bootstrap context initialization and once after the spring boot context initialization. I was only debugging the profiles in the first occurence. At that point, only the bootstrap.yml properties are loaded and not the ones from the application.yml file. The second occurence obviously had the profiles from my application.yml file.
My code worked as expected with a vanilla Spring Boot application. As the documentation states :
The Environment has already been prepared with all the usual property
sources that Spring Boot loads by default.
I was confused by the behaviour of my app which seemed to be different from that statement, but it was Spring Cloud's bootstrap that was messing with my debugging.
Since I need a PropertySource that has the highest precedence, I need to add it in the post bootstrap initialization for Spring Cloud apps. I used an init flag on my EnvironmentPostProcessor so it doesn't get executed twice and used the bootstrap.yml on Spring Cloud apps to set the profile.
TL;DR :
With Spring Cloud, an EnvironmentPostProcessor gets called twice: once after the bootstrap init and once after the normal Spring Boot context init. If you need injected properties and are targeting the Spring Cloud's post bootstrap initialization, use the bootstrap.yml instead of application.yml.

Disable Redis AutoConfig in spring boot when testing

I am trying to disable Redis when I am testing with spring boot. I have disabled my configuration but the auto config created a default connection and fails because it can't connect to a non-existent service. For testing I am content to just use a basic in-memory cache or a no-op cache. That doesn't work either. Here is what I have tried:
per this issue I added said configuration to my test app properties
spring.autoconfigure.exclude=org.springframework.boot.autoconfigure.data.redis.RedisAutoConfiguration
But. That gets me a bit further. But ultimately I get a NoSuchBeanDefinitionException redisTemplate - this is because redisReferenceResolver is trying to look that up.
Looking at my debugger right now, the bean it's trying to hydrate is:
org.springframework.data.redis.core.convert.ReferenceResolverImpl which is coming from spring-data-redis:1.8.0.RELEASE which is coming from this dependency: compile('org.springframework.boot:spring-boot-starter-data-redis') . I admit, the bean name is a bit misleading. The type it actually resolves to is not
The only other reference to redis is in our hibernate support.
Can someone explain how to turn this off for testing?

Try excluding this two auto-configuration classes in your test properties file:
spring.autoconfigure.exclude=org.springframework.boot.autoconfigure.data.redis.RedisAutoConfiguration,org.springframework.boot.autoconfigure.data.redis.RedisRepositoriesAutoConfiguration
or
exclude
org.springframework.boot.autoconfigure.data.redis.RedisAutoConfiguration
and set: spring.data.redis.repositories.enabled=false

With YAML syntax (& Spring Boot):
spring.autoconfigure:
exclude:
- org.springframework.boot.autoconfigure.data.redis.RedisAutoConfiguration
- org.springframework.boot.autoconfigure.data.redis.RedisRepositoriesAutoConfiguration
If you have SystemEnvironmentPropertySource in you app context you can use environment variable SPRING_AUTOCONFIGURE_EXCLUDE separating items with comma:
SPRING_AUTOCONFIGURE_EXCLUDE=org.springframework.boot.autoconfigure.data.redis.RedisAutoConfiguration,org.springframework.boot.autoconfigure.data.redis.RedisRepositoriesAutoConfiguration
Also try #EnableAutoConfiguration(exclude = {...}) on a #TestConfiguration annotated class.

If you dont want to change any files/code, you can also do this with an environment variable:
SPRING_AUTOCONFIGURE_EXCLUDE=org.springframework.boot.autoconfigure.data.redis.RedisAutoConfiguration,org.springframework.boot.autoconfigure.data.redis.RedisRepositoriesAutoConfiguration

How to update configuration of SpringBoot application at runtime without reloading whole ApplicationContext

I am trying to figure out how can I dynamically update/reload externalized configuration in a Spring Boot application without restarting the whole application.
Most of the advice involves reloading ApplicationContext after changing the externalized configuration, but that is equivalent to restarting the entire application, so this is not really all that useful.
Reading through SpringBoot reference documentation, I found a chapter 23.7 Typesafe Configuration Properties.
If I understand it correctly, this allows to define simple POJO classes that will hold your application (externalized) configuration values as attributes.
In theory at least, this scheme could be used to bind beans only once to the required configuration POJO and upon configuration change just update the values in the POJO. Components could easily pick up the changes next time they access getters on the POJO...
However, I have yet not managed to figure out how to enable this type of behavior. Is there some glaringly obvious way to dynamically update components annotated with #ConfigurationProperties when relevant configuration has changed?

It sounds like you're looking for #RefreshScope which is provided by Spring Cloud. From the Spring Cloud documentation:
A Spring #Bean that is marked as #RefreshScope will get special treatment when there is a configuration change. This addresses the problem of stateful beans that only get their configuration injected when they are initialized. For instance if a DataSource has open connections when the database URL is changed via the Environment, we probably want the holders of those connections to be able to complete what they are doing. Then the next time someone borrows a connection from the pool he gets one with the new URL.

Update spring beans dynamically. Is it possible?

Is there a way to update a Spring bean dynamically if the spring beans configuration changes?
E.g. assume that I have a spring bean with boolean property x and the spring beans has the value true when the application starts.
So spring creates the bean with the property x set to true.
Is there a way so that if I changes the property to x (while the application is running) that the property will be updated e.g. to false?

Calling the setter for x setX() method will do that.
But it should not be a prototype bean.

it is possible with the jrebel-spring integration. it monitors your configuration and TRIES to re-wire your beans at runtime.
Though i would not use it in production...only for playing around, testing etc

Spring reads configuration files at startup. If you really need to update configs while application running, you should manually implement all the chain: detecting config changes, validating config, detecting changed beans, updating beans in context.

Spring beans can be initialized using applicationContext.xml or even programatically. In your case; you will need to remove configurations from xml and add into java program. You can get some idea from How to programmatically create bean definition with injected properties? . Other good links were also available on google.