org.springframework.context.ApplicationContextAware

本文介绍了Spring框架中Aware接口的应用场景,通过示例代码展示了如何利用ApplicationContextAware获取ApplicationContext实例,进而访问配置好的Bean,降低了Bean对Spring的依赖。

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Spring中提供一些Aware相关接口,像是BeanFactoryAware、 ApplicationContextAware、ResourceLoaderAware、ServletContextAware等等,实现这些 Aware接口的Bean在被初始之后,可以取得一些相对应的资源。例如实作ApplicationContextAware的Bean,在Bean被初始后,将会被注入 ApplicationContext的实例等等。 Bean取得BeanFactory、ApplicationContextAware的实例目的是什么,一般的目的就是要取得一些档案资源的存取、相 关讯息资源或是那些被注入的实例所提供的机制



import org.springframework.context.ApplicationContextAware;

import org.springframework.context.ApplicationContext;

import org.springframework.beans.BeansException;

public class GlobalParamUtils implements ApplicationContextAware {

     private static ApplicationContext ac;

      public void setApplicationContext(ApplicationContext arg0) throws BeansException {
this.ac = arg0;

      }

 public static String generateCodeByType(String type) {

    String result = "";

    if (ac.containsBean("swmsBussinessCodeManager")) {

    BussinessCodeManager codeManager = (BussinessCodeManager) ac.getBean("swmsBussinessCodeManager");

    try {

        Method method = codeManager.getClass().getMethod(type, new Class[0]);

result = (String) method.invoke(codeManager, new Object[0]);

} catch (IllegalArgumentException e) {

e.printStackTrace();

} catch (IllegalAccessException e) {

e.printStackTrace();

} catch (InvocationTargetException e) {

e.printStackTrace();

} catch (SecurityException e) {

e.printStackTrace();

} catch (NoSuchMethodException e) {

e.printStackTrace();

}

    }

    return result;

    }

}



//swmsBussinessCodeManager在bean中的配置

        <bean class="com.vtradex.swms.server.service.GlobalParamUtils"/>

        <bean id="swmsBussinessCodeManager" parent="abstractTransactionProxy">
           <property name="target">
                    <bean class="com.vtradex.swms.server.service.sequence.pojo.DefaultBussinessCodeManager" parent="baseManager">
  <constructor-arg index="0">
<ref bean="sequenceGenerater"/>
</constructor-arg>
<constructor-arg index="1">
<ref bean="swmsSequenceDao"/>
</constructor-arg>
     </bean>
           </property>
</bean>

基本上,Spring虽然提供了这些Aware相关接口,然而Bean上若实现了这些界面,就算是与Spring发生了依赖,从另一个角度来看,虽然您可以直接在Bean上实现这些接口,但您也可以透过setter来完成依赖注入,例如:

public class GlobalParamUtils {

     private static ApplicationContext ac;

      public void setApplicationContext(ApplicationContext arg0) throws BeansException {
this.ac = arg0;

      }

 public static String generateCodeByType(String type) {

     String result = "";

     if (ac.containsBean("swmsBussinessCodeManager")) {  

     BussinessCodeManager codeManager =                          (BussinessCodeManager)ac.getBean("swmsBussinessCodeManager");

     try {

         Method method = codeManager.getClass().getMethod(type, new Class[0]);

result = (String) method.invoke(codeManager, new Object[0]);

} catch (IllegalArgumentException e) {

e.printStackTrace();

} catch (IllegalAccessException e) {

e.printStackTrace();

} catch (InvocationTargetException e) {

e.printStackTrace();

} catch (SecurityException e) {

e.printStackTrace();

} catch (NoSuchMethodException e) {

e.printStackTrace();

}

     }

     return result;

    }

}

注意这次我们并没有实作ApplicationContextAware,我们在程序中可以自行注入ApplicationContext实例:

ApplicationContext context = new ClassPathXmlApplicationContext("service.xml");


Bean而言,降低了对Spring的依赖,可以比较容易从现有的框架中脱离

Error starting ApplicationContext. To display the condition evaluation report re-run your application with 'debug' enabled. 2025-05-10 18:16:34.088 [main] ERROR org.springframework.boot.SpringApplication - Application run failed org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'forestBeanRegister' defined in class path resource [com/dtflys/forest/springboot/ForestAutoConfiguration.class]: Failed to instantiate [com.dtflys.forest.springboot.ForestBeanRegister]: Factory method 'forestBeanRegister' threw exception with message: Cannot invoke "org.springframework.context.ConfigurableApplicationContext.getBeanFactory()" because "this.applicationContext" is null at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:648) at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:636) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1355) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1185) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:562) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:522) at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:337) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:335) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:205) at org.springframework.context.support.PostProcessorRegistrationDelegate.registerBeanPostProcessors(PostProcessorRegistrationDelegate.java:277) at org.springframework.context.support.AbstractApplicationContext.registerBeanPostProcessors(AbstractApplicationContext.java:806) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:609) at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:146) at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:754) at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:456) at org.springframework.boot.SpringApplication.run(SpringApplication.java:335) at org.springframework.boot.SpringApplication.run(SpringApplication.java:1363) at org.springframework.boot.SpringApplication.run(SpringApplication.java:1352) at com.bx.implatform.IMPlatformApp.main(IMPlatformApp.java:25) Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.dtflys.forest.springboot.ForestBeanRegister]: Factory method 'forestBeanRegister' threw exception with message: Cannot invoke "org.springframework.context.ConfigurableApplicationContext.getBeanFactory()" because "this.applicationContext" is null at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:178) at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:644) ... 19 common frames omitted Caused by: java.lang.NullPointerException: Cannot invoke "org.springframework.context.ConfigurableApplicationContext.getBeanFactory()" because "this.applicationContext" is null at com.dtflys.forest.springboot.ForestBeanRegister.registerForestConfiguration(ForestBeanRegister.java:139) at com.dtflys.forest.springboot.ForestAutoConfiguration.forestBeanRegister(ForestAutoConfiguration.java:60) at com.dtflys.forest.springboot.ForestAutoConfiguration$$SpringCGLIB$$0.CGLIB$forestBeanRegister$4(<generated>) at com.dtflys.forest.springboot.ForestAutoConfiguration$$SpringCGLIB$$FastClass$$1.invoke(<generated>) at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:258) at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:370) at com.dtflys.forest.springboot.ForestAutoConfiguration$$SpringCGLIB$$0.forestBeanRegister(<generated>) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:568) at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:146) ... 20 common frames omitted Disconnected from the target VM, address: '127.0.0.1:57655', transport: 'socket'
最新发布
05-11
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