We have several java projects. Most of them are built with Struts 2.0 framework and few built with Spring 3.2. We want to consolidate all the back-end integration service into a separate project using spring 3.2 and import this jar file on all the projects. Here are my questions
What is the best way to initialize spring application-context for a jar based spring project? This jar is utilized by multiple web-project that are built using Struts and other non spring MVC frameworks.
I read How to package spring based library for reuse?. However, this question didn't answer on how to auto-load the application context when you a call a Service from the built spring-example.jar file.
For example. I have a WeatherService.java class in spring-framework.jar file. I want to import the spring-framework.jar file into another Struts-MVC based application and call WeatherService.java from an Action Class. I want the spring bean configuration to initiate automatically when calling the WeatherService.
You can use #Import annotation if using Java configurations or <import> tag if using XMl configs. With this approach you can reuse import one Spring context into another one.
Link to documentation:
http://docs.spring.io/spring/docs/current/spring-framework-reference/htmlsingle/#beans-java-using-import
EDIT:
If you are using maven, place your application-context.xml into src/main/resources. If not, make sure that it's on classpath.
Than if you are using XML config do
<import resource="classpath:application-config.xml"/>
or if you are using Java config do
#ImportResource("classpath:application-config.xml")
Related
We are using plugin architecture for one of our projects and we decided to use Spring pf4j for the same.
When we load the plugin via extensions - the application context is not able to find the beans created using #component in the plugin project- but the beans declared in #configuration classes are injected properly when we configure the plugin using register method - Is there anyway to scan and load the spring components in the plugin?
#Component in plugin is registered to main ApplicationContext via SpringExtensionFactory, make sure you set it up correctly in DefaultPluginManager correctly.
If you are going to use pf4j in SpringBoot, I would suggest you take a look sbp project. It is built upon pf4j and provides better integration with SpringBoot.
I want to start with the most simple Maven Project with a simple REST resource not using Spring Boot and generate a .war artifact that is deployed in a servlet container. I am using Eclipse IDE. So I would like to know what is the basic things in place needed to create such a Project.
I think I need at least this dependences:
Spring-core, Spring-mvc, Spring-web, Spring-context,
I also need the stuff with a class annotated with the #RestController annotation, with some method annotated with the #Requestmapping and so.
But whats the minimum content I should have in the WebContent directory and its subfolders META-INF, WEB-INF ... in order to the servlet container to know how to use the .war component? I dont want any HTML nor JSP pages.
In your WEB-INF folder, you will need a web.xml file. This is where you will configure your dispatcher servlet. This is the part of your application that receives requests and delegates them to the appropriate part of your application.
You will also need some sort of REST configuration file. You can define beans for Spring and component scan config.
A good explanation of this can be found here, https://www.programming-free.com/2014/01/spring-mvc-40-restful-web-services.html
Can I make a library with Spring framework, and then include that library in an application that uses the Spring framework?
Yes you can make a library that uses Spring, and then include a dependency on that jar in another application created with Spring. You will want a build tool that handles dependencies, like Maven or Gradle, and probably a repository manager like Nexus or Artifactory to store artifacts that you create.
You have to make sure that the jar gets included in the component scan performed by the hosting application. See the Spring reference documentation on Importing configurations.
If the library has its own Configuration, importing the Confuguration gets it included in the component scan.
Alternatively create a marker interface in your library like this:
#ComponentScan
public interface MyLibrary {}
then in the including application have a Configuration class annotated with
#ComponentScan(basePackageClasses= { MyLibrary.class })
and the including application will scan all Components in the package hierarchy starting from the package of the marker interface.
Spring is open source so you can contribute to it. Refer to https://github.com/spring-projects/spring-framework/blob/master/CONTRIBUTING.md for more details.
Yes, any Java based applicaiton (like spring framework) can be packaged as a JAR file and published to a repository (or store it locally to start simple)
This Jar file can be included as a dependency in another Java based application (like spring framework)
To add dependencies you can either use Maven or place it in a directory and add it to local classpath for the next application to use the library.
Your library becomes a reusable library (usually a JAR file) for all other java based applications
tl/dr (How) Is it possible to use a jar library, that uses Spring Boot for configuration in a non Spring Boot (regular old-school Spring) server.
We have the problem, that we have a Spring server, that is from the pre-Boot times and we want to create a new library for it. We would like to use Spring Boot in the library (i.e. #EnableAutoConfiguration for configuration). To include the library we have put an spring.xml into the library that enables component-scan inside the library. The classes inside the library use #EnableAutoConfiguration and #EnableWebSecurity to enable configuration and security.
If we include now the library into our server and import the XML file from the library into the server's XML file, only parts of the configuration are working. The #RequestMappings in the library are working and the interfaces are available. However Spring security fails to register it's default filter chain, leading to ugly errors, where the regular Spring Boot config should already work with AnonymousAuthorizationFilter, etc.
We debugged, that the FilterRegistrationBean in spring security is never configured when running that way (and is, if we are running as a Spring Boot application).
So is there a common way how to deal with Spring Boot enabled libraries inside old-school Spring servers?
Is placing a single XML to enable component-scan in the library and importing this XML inside the main server's XML the correct way to include Spring Boot libraries (and how would be the best way, if the server would use Spring Boot itself)?
Does anyone know of the issue with a missing Spring Security filter chain?
PS: I know that we can add the required filters manually. However if we would do that, we would anyway get rid of Spring Boot completely in the library, so this question mainly aims for how to do it with Spring Boot. Of course if it is the wrong way to enable Spring Boot inside a library, please also mention that :-)
I am trying to use to versions of spring in the same application: the first one is a webapp with spring 2.6 and the second it a jar client, with spring 4.0.2. The client communicates with another application and will be a dependency for the webapp. The problem is that the classloader will just load one time the common classes from spring and it will certainly fail.
I tried to use ElasticSearch aproach of using shaded dependencies(maven shade plugin) and relocate spring from the client to a different package (from org.springframework to my.springframework) and the uber jar seems to be constructed fine.
The issue is that Spring is based on spring.schemas and spring.handlers for validating xml config files and loads this files from classpath (META-INF folder and this paths are hardcoded in Spring code - e.q. PluggableSchemaResolver). I modified this files to point from org.srpingframework to my.springframework.
At runtime it seems that the classloader reads these files from the webapp, which has this files but with the real spring path and the exception is something like
org.realsearch.springframework.beans.FatalBeanException: Class [org.springframework.context.config.ContextNamespaceHandler] for namespace [http://www.springframework.org/schema/context] does not implement the [my.springframework.beans.factory.xml.NamespaceHandler] interface.
To me it seems that is impossible to achieve what I am trying (use tho spring versions in the same application with one of them relocated). Any ideas here? Am I wright?:d