I am extremely confused by Spring's Cloud module. I genuinely do not understand how to do the basic setup for it.
When I start my Spring Cloud application with the usual spring-boot parent, then I get this message: Spring MVC found on classpath, which is incompatible with Spring Cloud Gateway at this time. Please remove spring-boot-starter-web dependency.
Alright, so no spring-boot-starter-web dependency. But then I am looking at the official "Getting Started" guide of Spring Cloud: Spring Cloud getting started. I copy the mentioned dependencies 1:1 and end up with the same message in the server(?) start output as previously. Which makes sense, because the code on that site also sets the typical spring-boot-starter-parent, which also uses the spring-boot-starter-web dependency. That already contradicts with each other??
But then there is also a section called "Building a Simple Gateway Using Spring MVC or Webflux" in the official Spring Cloud documentation: Spring Cloud reference
I am really confused. When I try to start Spring Cloud in the same way that the getting-started documentation suggests, I get the mentioned "not-compatible" output message and also this exception:
Error creating bean with name 'routeDefinitionRouteLocator' defined in
class path resource
[org/springframework/cloud/gateway/config/GatewayAutoConfiguration.class]:
Unsatisfied dependency expressed through method
'routeDefinitionRouteLocator' parameter 4;
Trying to define a RouteLocator-bean myself so that the auto-configuration doesn't trigger does not seem to work. That's why I am thinking this whole Spring Cloud <> Spring MVC thing is causing the issue. But the existing documentation on Spring Cloud keeps contradicting each other whether or not you can use these two together or not or what the consequences are or anything.
Related
Can anyone please help me on how to integrate Olingo (Odata) in a Springboot Java Appln.
I'm pretty new to Spring boot and have implemented one project and wanted it to convert to Oling (Odata).
I have gone through various resources but with a bunch of different approaches not sure how to do it the correct way.
Please let me know if some has worked on it and can guide me.
link to the project on which I applied spring-boot.
If you are trying to integrate OlingoJPA there are a couple of things you will have to do
Implement JPAServiceFactory and initializeODataJPAContext, basically this is about defining the persistence unit and entity manager
Then you can create a Spring Boot Configuration to mount your OData endpoint and initialize the EntityManagerFactory
Then you can point to your database here
An finally you can define the JPA entities you want your service to expose
The full Spring Boot + JPA project sample is located Github. Feel free to go though it, raise an issue or submit a Pull request for impalements
Once I #EnableDataFlowServer my SpringBoot application, my own custom entities do not load. (I get the 'type not managed' exception which occurs when JPA isn't finding your entities).
These entities are found within another Spring module that I import, like
#Import({MyDomainsModule.class})
I'm using 2.0.0.m2 of Spring Cloud DataFlow.
Some debugging I've done:
If I add this to my Spring Boot application main class:
#EntityScan({
"com.company.mydomain.entities"
})
Then my entities start to load as usual, but then Spring DataFlow breaks. For example, any time I try to load the UI, I'll get:
|ne.jdbc.spi.SqlExceptionHelper| Table 'dataflow.appregistration' doesn't exist
That makes me thinking by simply adding the EntityScan, I broke some naming strategy since the actual name of the table is of course app_registration
I think this is mostly a 'how do I do multiple locations of JPA-based code in one project', rather than a Spring Cloud DataFlow question. But knowing the fix might require a better understanding of how SCDF. I've checked out the project and reading up both Spring Boot and how SCDF configures itself.
Any help is greatly appreciated!
I had a bad strategy coming in from one of my properties, overriding what SCDF added this to my application.properties.
So to be explicit, I set this in my properties:
spring.jpa.hibernate.naming.physical-strategy=org.springframework.boot.orm.jpa.hibernate.SpringPhysicalNamingStrategy
spring.jpa.hibernate.naming.implicit-strategy=org.springframework.boot.orm.jpa.hibernate.SpringImplicitNamingStrategy
And then my SpringBoot application looks like
#SpringBootApplication(exclude = LocalDataFlowServerAutoConfiguration.class)
#Import({MyDomainModule.class})
#EnableDataFlowServer
// EnableDataFlowServer has an EntityScan, which causes ours to not be picked up!
// Look in DataFlowControllerAutoConfiguration for more information
#EntityScan({
"com.company.mydomain.entities"
})
Following the online docs for adding jersey to Sring boot, it appears I just need to include the following package
spring-boot-starter-jersey
Actually, it states that Spring Boot provides automatic configuration by including this package.
Where can I find out what exactly is happening?
If I don't add this package then what is NOT configured?
I tried searching for the package in google but got no specific explanation only saying that it automatically configures, but configures what?
I would like to know a little more of what is happening behind the scenes.
All of the auto-configuration code for all that Spring Boot supports is in the spring-boot-autoconfigure module. If you look through the packages, you will see a jersey package.
The "starter" modules generally do not have any code (of course unless it is a third-party module). How it works is that the code in the auto-configuration has some annotations that are #ConditionalOnXxx, where the condition be anything from a class being on the classpath. If this class is not available, then the auto-configuration will not take place. That's pretty much all adding the jersey starter module does: it adds the jersey dependencies so that the auto-configurer will applied.
Now what exactly is being auto-configured specifically for Jersey? Check out the source for the JerseyAutoConfiguration. Basically what you are going to see is your ResourceConfig being injected into the configurer. From that ResourceConfig, it creates Jersey's ServletContainer (which is the main entry point for Jersey.
Then, depending on our properties configuration, either a FilterRegistrationBean or a ServletRegistrationBean is created as a Spring bean, wrapping Jersey's ServletContainer. Jersey can be created as a Servlet or a Servlet Filter. Whichever one we configure we be used.
And that's it for the Jersey configuration. Spring Boot will get a servlet container (e.g. Tomcat, Jetty) from some other auto-configuration, and take the Filter/ServletRegistrationBean and add the Servlet/Filter to that servlet container.
Also, not really that important, but the auto-configuration also give us some Jackson configuration helpers. For example, instead of configuring our own ContextResolver, we can just configure an ObjectMapper Spring bean.
That's really all you get. It's nothing so spectacular that you couldn't just do it yourself without depending on the auto-configuration.
I would recommend learning a little more about how Spring Boot works to provide the automatic configuration in general.
A good reference is the spring boot reference guide. http://docs.spring.io/spring-boot/docs/1.5.3.RELEASE/reference/htmlsingle/#common-application-properties
You can look at the common application properties in appendix A to see what all spring allows you to configure out of the box.
The Reference guide also gives a high level of what "spring-boot-starter-jersey" if you search for it on the page.
They also have a few samples that you can go through and debug to follow along if that is a way for you to learn.
Hope that gives you a starting point for learning!
I am going to create simple rest service using spring 3 and hibernate 3. There is no chance for me to use higher version of spring due to legacy business component that is based on hibernate 3.
For such purposes I've tried to use SpringApplication.run, bet recieved following exception:
Exception in thread "main" java.lang.IllegalAccessError: tried to access method org.springframework.core.io.support.SpringFactoriesLoader.loadFactoryNames
Is it possible to use spring-boot-maven-plugin with old spring version? Would be good to know any alternative ways in this direction.
Spring Boot (and all the related tools, e.g the maven plugin) expect Spring v4 and above. Please see the official documentation here.
By default, Spring Boot 1.3.2.BUILD-SNAPSHOT requires Java 7 and Spring Framework 4.1.5 or above.
What's the best method to initiate a new Spring Project ?
Initiating Spring project is a lot of pain with various xml and db configuration.
Is there an "official" repository with complete sample project, as MVC with db access and so ?
Spring Boot may also be the solution, but some point still not clear to me :
How to add external components (such as Quartz) without creating some xml config ? (No such xml in Boot apparently)
Is a Spring Boot builded app is production-proof ?
As writen in the comments http://start.spring.io/ is the best way to start Spring boot project(STS has integration for it).
If you want to use something that is not supported by Spring Boot you can init spring beans the same way you do it in xml, just use java configuration. See this for example: http://www.tutorialspoint.com/spring/spring_java_based_configuration.htm
Also useing xml is still available. You can add #ImportResource on your Configuration class
#EnableAutoConfiguration
#Configuration
#ImportResource({"classpath*:applicationContext.xml"})