Question

我在Spring Boot中通过setter将一个bean注入另一个bean中。在setter内时，该bean不是非null，但是当我从另一个方法调用它时，它将返回null。

我尝试了所有组合（通过构造函数和设置器注入，仅自动装配字段，自动装配字段和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)

我想这个例外根本不会有用。我正在使用JavaFX，但是异常来自Spring的情况并不重要。

我不知道我是否缺少任何注释或配置错误。

编辑：

实际上，这是关于Spring和JavaFX创建自己的TargetClass实例的问题，因此BeanToInject是重复的。按照本教程Add Spring to JavaFX，我通过让Spring管理JavaFX控制器来解决它。感谢所有人的帮助！

Answer 1

一个例子

BeanOne（BeanToInject）

    path('test/<int:pk>/', views.Test.as_view(),name="test"),

BeanTwo（TargetClass）

public class BeanOne {

}

配置。请注意，此处仅使用@Bean

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);
    }


}

测试应用

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();
    }
}

运行时的输出

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();
    }

}

创建BeanTwo时，Spring容器将注入BeanOne实例。在此过程中，将显示“发件人”消息。

然后我们从ApplicationContext获取此BeanTwo实例，并调用testMethod（），它给出了“ From testMethod”消息。

从外观上看，在您的情况下，您将自己创建BeanTwo（TargetClass）实例（新TargetClass（））。这样的bean不受Spring容器的管理，并且在创建时将BeanOne引用设置为null。

在setter之外，自动装配的bean为空

1 个答案: