问题
Hi i want to know what are the different ways to get ApplicationContext Object in Spring? I know only one way that is,
ApplicationContext context = new ClassPathXmlApplicationContext("Beans.xml");
is there any other ways? if it is please let me know.
Thanks.
回答1:
You can also use annotation based configuration
@Configuration
public class Config {
@Bean
public Bean1 bean1() {
return new Bean1();
}
public static void main(String[] args) {
ApplicationContext ctx = new AnnotationConfigApplicationContext(Config.class);
}
}
回答2:
You can implement the interface ApplicationContextAware, like this :
public class MyClass implements ApplicationContextAware {
private ApplicationContext applicationContext;
@Override
public void setApplicationContext(ApplicationContext applicationContext) {
this.applicationContext = applicationContext;
}
}
If you are using annotation, you could also autowire it
@Autowired
private ApplicationContext applicationContext;
Also, the code you wrote does not get an existing application context, it creates one.
回答3:
Well, there are a lot of ways out there, I wonder whom would know them all...
But first, we need to make a difference between instanting a new context, or getting a running and existing application-context.
By new ***ApplicationContext a new context will be created. Therefore all Subclasses of org.springframework.context.ApplicationContext can be used to create a new ApplicationContext. You can find all implementing classes here. The new way to instantiate a spring-context is through AnnotationConfigApplicationContext.
Also, you can add a displatcher-servlet or an servlet-listener in your web.xml. Or use a framework like gemini-blueprint in an osgi-environment which starts all xml-files in meta-inf/spring. (e.g. eclipse virgo)
On the other hand, you can get an existing context (which means not a new one) through different ways:
- ApplicationContextAware
Implement the ApplicationContextAware interface and you will get the context via setApplicationContext(ApplicationContext applicationContext) method.
Just add
@Autowired private ApplicationContext applicationContext;to your spring bean. But make sure it is a spring bean.In your web-application, you can get the context of your listener-context via
ApplicationContextUtils.getWebApplicationContext( servletcontext)
There would a lot of more ways, but these are those which popped up in my mind quickly.
回答4:
If you are referring to the possible way you can create an ApplicationContext and not to the ways such an instance can be passed through your code then I suggest taking a look at the Spring javadoc for ApplicationContext. So based on this the concrete implementations of this interface are:
org.springframework.context.annotation.AnnotationConfigApplicationContext
Standalone application context, accepting annotated classes as input - in particular @Configuration-annotated classes, but also plain @Component types and JSR-330 compliant classes using javax.inject annotations. Allows for registering classes one by one using register(Class...) as well as for classpath scanning using scan(String...).
org.springframework.web.context.support.AnnotationConfigWebApplicationContext
This is essentially the equivalent of AnnotationConfigApplicationContext for a web environment.
org.springframework.context.support.ClassPathXmlApplicationContext
Standalone XML application context, taking the context definition files from the class path, interpreting plain paths as class path resource names that include the package path (e.g. "mypackage/myresource.txt"). Useful for test harnesses as well as for application contexts embedded within JARs.
org.springframework.context.support.FileSystemXmlApplicationContext
Standalone XML application context, taking the context definition files from the file system or from URLs, interpreting plain paths as relative file system locations (e.g. "mydir/myfile.txt"). Useful for test harnesses as well as for standalone environments.
org.springframework.context.support.GenericApplicationContext
Generic ApplicationContext implementation that [...] does not assume a specific bean definition format
org.springframework.context.support.GenericXmlApplicationContext
Convenient application context with built-in XML support. This is a flexible alternative to ClassPathXmlApplicationContext and FileSystemXmlApplicationContext, to be configured via setters, with an eventual AbstractApplicationContext.refresh() call activating the context.
org.springframework.context.support.GenericGroovyApplicationContext
An ApplicationContext implementation that extends GenericApplicationContext. [...] Consider this as the equivalent of GenericXmlApplicationContext for Groovy bean definitions, or even an upgrade thereof since it seamlessly understands XML bean definition files as well.
org.springframework.web.context.support.GenericWebApplicationContext
Subclass of GenericApplicationContext, suitable for web environments.
org.springframework.web.context.support.GroovyWebApplicationContext
WebApplicationContext implementation which takes its configuration from Groovy bean definition scripts and/or XML files, as understood by an GroovyBeanDefinitionReader. This is essentially the equivalent of GenericGroovyApplicationContext for a web environment.
org.springframework.jca.context.ResourceAdapterApplicationContext
ApplicationContext implementation for a JCA ResourceAdapter. Needs to be initialized with the JCA BootstrapContext, passing it on to Spring-managed beans that implement BootstrapContextAware.
org.springframework.context.support.StaticApplicationContext
ApplicationContext implementation which supports programmatic registration of beans and messages, rather than reading bean definitions from external configuration sources. Mainly useful for testing.
org.springframework.web.portlet.context.StaticPortletApplicationContext
Static Portlet-based ApplicationContext implementation for testing. Not intended for use in production applications.
org.springframework.web.context.support.StaticWebApplicationContext
Static WebApplicationContext implementation for testing. Not intended for use in production applications.
org.springframework.web.portlet.context.XmlPortletApplicationContext
Portlet-based WebApplicationContext implementation which takes its configuration from XML documents, understood by an XmlBeanDefinitionReader.
org.springframework.web.context.support.XmlWebApplicationContext
WebApplicationContext implementation which takes its configuration from XML documents, understood by an XmlBeanDefinitionReader. This is essentially the equivalent of GenericXmlApplicationContext for a web environment.
来源：https://stackoverflow.com/questions/28767479/what-are-the-ways-to-get-applicationcontext-object-in-spring