是否有一种方法可以在Spring应用程序中静态/全局地请求ApplicationContext的副本?
假设主类启动并初始化了应用程序上下文,它是否需要通过调用堆栈向下传递给任何需要它的类,或者类是否有一种方法来请求先前创建的上下文?(我假设它必须是单例的?)
是否有一种方法可以在Spring应用程序中静态/全局地请求ApplicationContext的副本?
假设主类启动并初始化了应用程序上下文,它是否需要通过调用堆栈向下传递给任何需要它的类,或者类是否有一种方法来请求先前创建的上下文?(我假设它必须是单例的?)
当前回答
看一下ContextSingletonBeanFactoryLocator。它提供静态访问器来获取Spring的上下文,假设它们已经以某种方式注册。
它并不漂亮,而且可能比您想要的还要复杂,但它是有效的。
其他回答
方法1:您可以通过实现ApplicationContextAware接口来注入ApplicationContext。参考链接。
@Component
public class ApplicationContextProvider implements ApplicationContextAware {
private ApplicationContext applicationContext;
public ApplicationContext getApplicationContext() {
return applicationContext;
}
@Override
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
this.applicationContext = applicationContext;
}
}
方法2:在任何spring托管bean中自动装配应用程序上下文。
@Component
public class SpringBean {
@Autowired
private ApplicationContext appContext;
}
参考链接。
看一下ContextSingletonBeanFactoryLocator。它提供静态访问器来获取Spring的上下文,假设它们已经以某种方式注册。
它并不漂亮,而且可能比您想要的还要复杂,但它是有效的。
这里有一个很好的方法(不是我的,原始参考在这里: http://sujitpal.blogspot.com/2007/03/accessing-spring-beans-from-legacy-code.html
我使用过这种方法,效果很好。基本上,它是一个简单的bean,包含对应用程序上下文的(静态)引用。通过在spring配置中引用它来初始化它。
看看原来的裁判,非常清楚。
我知道这个问题已经有了答案,但是我想分享一下我用来检索Spring Context的Kotlin代码。
我不是专家,所以我愿意接受批评、评论和建议:
https://gist.github.com/edpichler/9e22309a86b97dbd4cb1ffe011aa69dd
package com.company.web.spring
import com.company.jpa.spring.MyBusinessAppConfig
import org.springframework.beans.factory.annotation.Autowired
import org.springframework.context.ApplicationContext
import org.springframework.context.annotation.AnnotationConfigApplicationContext
import org.springframework.context.annotation.ComponentScan
import org.springframework.context.annotation.Configuration
import org.springframework.context.annotation.Import
import org.springframework.stereotype.Component
import org.springframework.web.context.ContextLoader
import org.springframework.web.context.WebApplicationContext
import org.springframework.web.context.support.WebApplicationContextUtils
import javax.servlet.http.HttpServlet
@Configuration
@Import(value = [MyBusinessAppConfig::class])
@ComponentScan(basePackageClasses = [SpringUtils::class])
open class WebAppConfig {
}
/**
*
* Singleton object to create (only if necessary), return and reuse a Spring Application Context.
*
* When you instantiates a class by yourself, spring context does not autowire its properties, but you can wire by yourself.
* This class helps to find a context or create a new one, so you can wire properties inside objects that are not
* created by Spring (e.g.: Servlets, usually created by the web server).
*
* Sometimes a SpringContext is created inside jUnit tests, or in the application server, or just manually. Independent
* where it was created, I recommend you to configure your spring configuration to scan this SpringUtils package, so the 'springAppContext'
* property will be used and autowired at the SpringUtils object the start of your spring context, and you will have just one instance of spring context public available.
*
*Ps: Even if your spring configuration doesn't include the SpringUtils @Component, it will works tto, but it will create a second Spring Context o your application.
*/
@Component
object SpringUtils {
var springAppContext: ApplicationContext? = null
@Autowired
set(value) {
field = value
}
/**
* Tries to find and reuse the Application Spring Context. If none found, creates one and save for reuse.
* @return returns a Spring Context.
*/
fun ctx(): ApplicationContext {
if (springAppContext!= null) {
println("achou")
return springAppContext as ApplicationContext;
}
//springcontext not autowired. Trying to find on the thread...
val webContext = ContextLoader.getCurrentWebApplicationContext()
if (webContext != null) {
springAppContext = webContext;
println("achou no servidor")
return springAppContext as WebApplicationContext;
}
println("nao achou, vai criar")
//None spring context found. Start creating a new one...
val applicationContext = AnnotationConfigApplicationContext ( WebAppConfig::class.java )
//saving the context for reusing next time
springAppContext = applicationContext
return applicationContext
}
/**
* @return a Spring context of the WebApplication.
* @param createNewWhenNotFound when true, creates a new Spring Context to return, when no one found in the ServletContext.
* @param httpServlet the @WebServlet.
*/
fun ctx(httpServlet: HttpServlet, createNewWhenNotFound: Boolean): ApplicationContext {
try {
val webContext = WebApplicationContextUtils.findWebApplicationContext(httpServlet.servletContext)
if (webContext != null) {
return webContext
}
if (createNewWhenNotFound) {
//creates a new one
return ctx()
} else {
throw NullPointerException("Cannot found a Spring Application Context.");
}
}catch (er: IllegalStateException){
if (createNewWhenNotFound) {
//creates a new one
return ctx()
}
throw er;
}
}
}
现在,spring上下文是公开可用的,能够独立于上下文调用相同的方法(junit测试,bean,手动实例化类),就像下面这个Java Servlet:
@WebServlet(name = "MyWebHook", value = "/WebHook")
public class MyWebServlet extends HttpServlet {
private MyBean byBean
= SpringUtils.INSTANCE.ctx(this, true).getBean(MyBean.class);
public MyWebServlet() {
}
}
请注意;下面的代码将创建新的应用程序上下文,而不是使用已经加载的上下文。
private static final ApplicationContext context =
new ClassPathXmlApplicationContext("beans.xml");
还要注意,beans.xml应该是src/main/resources的一部分,这意味着在war中它是WEB_INF/classes的一部分,其中真正的应用程序将通过Web.xml中提到的applicationContext.xml加载。
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>META-INF/spring/applicationContext.xml</param-value>
</context-param>
在ClassPathXmlApplicationContext构造函数中很难提及applicationContext.xml路径。ClassPathXmlApplicationContext("META-INF/spring/applicationContext.xml")无法定位文件。
因此,最好通过使用注释来使用现有的applicationContext。
@Component
public class OperatorRequestHandlerFactory {
public static ApplicationContext context;
@Autowired
public void setApplicationContext(ApplicationContext applicationContext) {
context = applicationContext;
}
}