我有一个MyTask
实现的类,Runnable
并且可以在任何给定时刻实例化许多这样的对象.有些属性我想自动MyTask
上课.
但我认为,如果我MyTask
用@Component
它标记它将成为一个弹簧管理的单身正确吗?这不是我想要的,我需要由TaskExecutor运行这个类的许多独立实例.
所以我的问题:
a)我对@Component
注释的理解从根本上是错误的吗?它不会MyTask
成为一个由春季管理的单身人士吗?
b)我应该使用其他注释,以便spring检测@Autowired
并注入属性吗?
c)弹簧自动装配不适用于非单件容器/类MyTask
吗?
更新#1 - 这些不起作用:
public class MyTask implements Runnable { // I want this class to be non-singleton @Autowired public SomeSpecialSpringConfiguredConnectionClass blah; // this is the singleton bean that should be injected @Override public void run() { // BLAH IS NULL, this shouldn't be NULL, that is not what I want // which makes sense considering Spring never knew it had to work // on this class } } @Component public class MyTask implements Runnable { // I want this class to be non-singleton @Autowired public SomeSpecialSpringConfiguredConnectionClass blah; // this is the singleton bean that should be injected @Override public void run() { // this works BUT now MyTask is singleton :( } } @Component @Scope("prototype") public class MyTask implements Runnable { // I want this class to be non-singleton @Autowired public SomeSpecialSpringConfiguredConnectionClass blah; // this is the singleton bean that should be injected @Override public void run() { // BLAH IS NULL, again ... this shouldn't be NULL, that is not what I want } }
更新#2 - 在等待更多关于如何做到这一点的建议时,我正在研究:Using AspectJ to dependency inject domain objects with Spring
作为替代方案.
首先,默认情况下,使用@Component声明并由弹簧组件扫描拾取的bean将成为弹簧管理的单例.
我不知道你如何使用MyTask,但在你的情况下使用AspectJ是过分的,将MyTask声明为一个弹簧管理的bean没有多大意义.另一种方法是:
将MyTask定义为普通java类,并添加构造函数以初始化依赖项blah
autowire blah在你使用的地方MyTask
,并在每次要执行任务时实例化MyTask对象,如下所示:
//autowire the dependency of MyTask in another spring bean with default singleton scope @Autowired private SomeSpecialSpringConfiguredConnectionClass blah //create task and wire the blah yourself executor.submit(new MyTask(blah))
@Component注释允许它们在使用上下文进行类路径扫描时进行自动检测:组件扫描就是这样做的.@Service和@Component之间有一条细线,在这种情况下它无论如何都不会影响.
弹簧自动装配可以用于原型和单件范围.在原型范围的情况下,虽然没有调用bean的销毁的生命周期回调.
它在Spring文档页面上得到了很好的解释. http://docs.spring.io/spring/docs/3.0.0.M3/reference/html/ch04s04.html
我没有看到为什么你提到的任何东西不应该工作的原因.
他是我试图更好地解释它的工作样本.
public class SpringContainerStartClass { public static void main(final String[] args) { final ClassPathXmlApplicationContext bf = new ClassPathXmlApplicationContext("beans.xml"); final MainApplication1 bean = (MainApplication1) bf.getBean("mainApplication1"); bean.getMyTask().printSomething(); } }
这是应用程序的起点.
这是你的myTask类
@Component(value = "myTask") @Scope(value = "prototype") public class MyTask implements Runnable { @Autowired private SomeSpecialSpringConfiguredConnectionClass someSpringObject; @Override public void run() { System.out.println("running now"); } public void printSomething() { System.out.println(someSpringObject.getValue()); } public SomeSpecialSpringConfiguredConnectionClass getSomeSpringObject() { return someSpringObject; } public void setSomeSpringObject(final SomeSpecialSpringConfiguredConnectionClass someSpringObject) { this.someSpringObject = someSpringObject; } }
另外两个类来展示原型范围是如何工作的
@Component public class MainApplication1 { @Autowired private MyTask myTask; public MyTask getMyTask() { return myTask; } public void setMyTask(final MyTask myTask) { this.myTask = myTask; } } @Component public class MainApplication2 { @Autowired private MyTask myTask; public MyTask getMyTask() { return myTask; } public void setMyTask(final MyTask myTask) { this.myTask = myTask; } }
一个BeanPostprocessor,它将向您展示如何创建对象
public class InstantiationTracingBeanPostProcessor implements BeanPostProcessor { @Override public Object postProcessBeforeInitialization(final Object bean, final String beanName) throws BeansException { return bean; } @Override public Object postProcessAfterInitialization(final Object bean, final String beanName) throws BeansException { System.out.println("Bean '" + beanName + "' created : " + bean.toString()); return bean; } }
你的SomeSpringConfig类
@Service public class SomeSpecialSpringConfiguredConnectionClass { private String value = "someValue"; public String getValue() { return value; } public void setValue(final String value) { this.value = value; } }
运行此示例时,您会注意到控制台上的输出是
INFO: Loading XML bean definitions from class path resource [beans.xml] Jan 02, 2014 12:07:15 PM org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons INFO: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@26efabf8: defining beans [mainApplication1,mainApplication2,myTask,someSpecialSpringConfiguredConnectionClass,org.springframework.context.annotation.internalConfigurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor,com.stackoverflow.DIQuestion.InstantiationTracingBeanPostProcessor#0,org.springframework.context.annotation.ConfigurationClassPostProcessor.importAwareProcessor]; root of factory hierarchy Bean 'someSpecialSpringConfiguredConnectionClass' created : com.stackoverflow.DIQuestion.SomeSpecialSpringConfiguredConnectionClass@1e20d04b Bean 'myTask' created : com.stackoverflow.DIQuestion.MyTask@175d6331 Bean 'mainApplication1' created : com.stackoverflow.DIQuestion.MainApplication1@741b31f2 Bean 'myTask' created : com.stackoverflow.DIQuestion.MyTask@2c2815d3 Bean 'mainApplication2' created : com.stackoverflow.DIQuestion.MainApplication2@7bb0e64a
如果您注意到carefulyy,则myTask中有2个对象具有不同的哈希码.
如果你将myTask的范围更改为"Singleton",那么这将是输出.
INFO: Loading XML bean definitions from class path resource [beans.xml] Jan 02, 2014 12:08:35 PM org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons INFO: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@26efabf8: defining beans [mainApplication1,mainApplication2,myTask,someSpecialSpringConfiguredConnectionClass,org.springframework.context.annotation.internalConfigurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor,com.stackoverflow.DIQuestion.InstantiationTracingBeanPostProcessor#0,org.springframework.context.annotation.ConfigurationClassPostProcessor.importAwareProcessor]; root of factory hierarchy Bean 'someSpecialSpringConfiguredConnectionClass' created : com.stackoverflow.DIQuestion.SomeSpecialSpringConfiguredConnectionClass@1e20d04b Bean 'myTask' created : com.stackoverflow.DIQuestion.MyTask@175d6331 Bean 'mainApplication1' created : com.stackoverflow.DIQuestion.MainApplication1@741b31f2 Bean 'mainApplication2' created : com.stackoverflow.DIQuestion.MainApplication2@2c2815d3
在这种情况下,为"myTask"创建了一个对象
这有帮助吗?