自动连接的bean在setter之外为null

Question

我在Spring Boot中通过setter将一个bean注入到另一个bean中。bean在setter内部时不为null，但当我从另一个方法调用它时，它返回null。

我已经尝试了所有的组合(通过构造函数和setter注入，仅自动布线字段，自动布线字段和setter…(

SpringConfiguration.java

@Bean
public BeanToInject beanToInject(){
return new BeanToInject();
}
@Bean
public TargetClass targetClass(){
return new TargetClass();
}

BeanToInject.java

@Component
public class BeanToInject{
public BeanToInject(){}
//More stuff
}

TargetClass.java

@Component
public class TargetClass {
private BeanToInject beanToInject;
public TargetClass(){}
@Autowired
public void setBeanToInject(BeanToInject beanToInject){
this.beanToInject = beanToInject;
System.out.print("1. " + this.beanToInject); //Here is instanced
}
public void anotherMethod(){
System.out.print("2. " + beanToInject); //Here is null
beanToInject.doSomeStuff(); //Here comes the exception
}
}

输出：

//Spring stuff...
1. com.foo.bar.BeanToInject@blahblah
2. null
//------And then, the exception
Exception in thread "JavaFX Application Thread" java.lang.NullPointerException
at acteso.standard.deskapp.gui.LoginController.btAceptar(LoginController.java:82)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
at javafx.event.Event.fireEvent(Event.java:198)
at javafx.scene.Node.fireEvent(Node.java:8411)
at javafx.scene.control.Button.fire(Button.java:185)
at com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:182)
at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:96)
at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:89)
at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
at javafx.event.Event.fireEvent(Event.java:198)
at javafx.scene.Scene$MouseHandler.process(Scene.java:3757)
at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3485)
at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762)
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2494)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:394)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$2(GlassViewEventHandler.java:432)
at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:410)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:431)
at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
at com.sun.glass.ui.View.notifyMouse(View.java:937)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$3(WinApplication.java:177)
at java.lang.Thread.run(Unknown Source)

我想这个例外根本没有用。我正在使用JavaFX，但当异常来自Spring时，这并不重要。

我不知道我是否遗漏了任何注释，或者我是否配置错误。

编辑：

事实上，Spring和JavaFX创建自己的TargetClass实例是个问题，所以BeanToInject是重复的。我通过让Spring管理JavaFX控制器来解决这个问题，遵循本教程：将Spring添加到JavaFX。感谢大家的帮助！

Answer 1

示例

BeanOne(BeanToInject(

public class BeanOne {
}

BeanTwo(TargetClass(

public class BeanTwo {
BeanOne beanOne;

@Autowired
public void setBeanOne(BeanOne beanOne) {
this.beanOne = beanOne;
System.out.println("From setter "+beanOne);
}
public void testMethod() {
System.out.println("From testMethod "+beanOne);
}

}

配置。注意，这里只使用@Bean

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class TestConfiguration {
@Bean
public BeanOne getBeanOne() {
return new BeanOne();
}
@Bean
public BeanTwo getBeanTwo() {
return new BeanTwo();
}
}

测试应用程序

public class TestApp {
public static void main(String[] args) {
AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(TestConfiguration.class);
ctx.registerShutdownHook();
BeanTwo bean = ctx.getBean(BeanTwo.class);
bean.testMethod();
}
}

运行时的输出

From setter BeanOne@7f1302d6
From testMethod BeanOne@7f1302d6

Spring容器在创建BeanTwo时注入BeanOne的实例。在此过程中，将打印"来自setter"消息。

然后，我们从ApplicationContext获得这个BeanTwo实例，并调用testMethod((，它给出"from-testMethod"消息。

从外观上看，在您的案例中，您正在自己创建BeanTwo(TargetClass(实例(new TargetClass(((。这样的bean不由Spring Container管理，并且在创建时BeanOne引用将为null。