java - @Autowire 调用期间未实例化服务类

标签 java spring autowired spring-boot stomp

我正尝试在我的消息传递应用程序中使用 @Service 类，但是当我尝试使用通用类时，该类并未通过 @Autowire 实例化。它仅在我使用 Controller 时实例化。

这是我的 Controller :

    package hello;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.messaging.handler.annotation.MessageMapping;
import org.springframework.messaging.handler.annotation.SendTo;
import org.springframework.messaging.simp.SimpMessageSendingOperations;
import org.springframework.messaging.simp.SimpMessagingTemplate;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

import hello.Application;

@Controller
public class HelloController {


    @Autowired
    private MessageSender sender;

    @RequestMapping(value="/", method=RequestMethod.GET)
    public String index() {
        return "index";
    }

    @MessageMapping("/hello")
    @SendTo("/topic/greetings")
    public Greeting greeting(HelloMessage message) throws Exception {
        System.out.println("Sending message...");
        beginRoute(message.getName());
        sender.greet("thunder");
        return new Greeting("Hello, " + message.getName() + "!");
    }

    public void beginRoute(String message) {
        Application.startBody(message);
    }
}

上面对 sender.greet 的调用是成功的。

这是我尝试在其中使用该服务的另一个类:

package com.routing.integration;

import hello.*;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.messaging.simp.SimpMessageSendingOperations;
import org.springframework.messaging.simp.SimpMessagingTemplate;
import org.springframework.stereotype.Component;


@Component
public class modifier {

    @Autowired
    private MessageSender sender;

    public boolean adder(String words) throws Exception {

        sender.greet(words);
    }
}

当我尝试如上所述调用 sender.greet 时，我得到一个 NullPointerException 并且在调试时，我发现在调用 sender.greet 时 sender 为 null。服务类不是在修饰符中实例化吗？

最后，这里是 MessageSender 服务类:

@Service
public class MessageSender {

    @Autowired
    private SimpMessagingTemplate template;


    @RequestMapping(value="/hello", method=RequestMethod.POST)
    public void greet(String greeting) {
        Greeting text = new  Greeting("Goodbye, " + greeting + "!");
        this.template.convertAndSend("/topic/greetings", text);
    }

}

如何确保@Autowire 在每个类中实例化 MessageSender？

编辑

这里是调用修改器的地方。它是由 Camel 路线制成的:

    <?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:camel="http://camel.apache.org/schema/spring"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:core="http://activemq.apache.org/schema/core"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context     http://www.springframework.org/schema/context/spring-context.xsd
    http://camel.apache.org/schema/osgi http://camel.apache.org/schema/osgi/camel-osgi.xsd
    http://camel.apache.org/schema/spring http://camel.apache.org/schema/spring/camel-spring.xsd
    http://activemq.apache.org/schema/core http://activemq.apache.org/schema/core">

<camelContext xmlns="http://camel.apache.org/schema/spring">

<route>
        <from uri="activemq:queue:testQSource"/>

        <choice>
            <when>
                <method ref="securityBean"/>
                <log message="Routing message from testQSource to testQDestination queue with data ${body}"/>

                <to uri="activemq:queue:testQDestination"/>
                <to uri="activationBean"/>
                <to uri="accountVerificationBean"/>
                <to uri="billingCheckingBean"/>
                <to uri="deviceConnectorBean"/>
                <to uri="deviceActivatorBean"/>
                <log message="Account activated: ${body}"/>
            </when>
            <otherwise>
                <log message="message went to stomp: ${body}"/>
            </otherwise>
        </choice>
</route>
</camelContext>


<camel:camelContext id="camel-client">
    <camel:template id="camelTemplate" />
</camel:camelContext>

<bean id="activemq" class="org.apache.activemq.camel.component.ActiveMQComponent">
    <property name="brokerURL" value="tcp://localhost:61616" />
</bean>
<bean id="browserBean" class="hello.HelloController"/>
<bean id="securityBean" class="com.routing.integration.modifier"/>
<bean id="activationBean" class="com.routing.integration.ActionApp"/>
<bean id="accountVerificationBean" class="com.routing.integration.AccountVerifier"/>
<bean id="billingCheckingBean" class="com.routing.integration.BillingChecker"/>
<bean id="deviceConnectorBean" class="com.routing.integration.DeviceConnector"/>
<bean id="deviceActivatorBean" class="com.routing.integration.DeviceActivator"/>

</beans>

这是堆栈跟踪:

Stacktrace
---------------------------------------------------------------------------------------    ------------------------------------------------
java.lang.NullPointerException
at com.routing.integration.modifier.adder(modifier.java:19)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.apache.camel.component.bean.MethodInfo.invoke(MethodInfo.java:407)
at org.apache.camel.component.bean.MethodInfo$1.doProceed(MethodInfo.java:278)
at org.apache.camel.component.bean.MethodInfo$1.proceed(MethodInfo.java:251)
at org.apache.camel.component.bean.BeanProcessor.process(BeanProcessor.java:166)
at org.apache.camel.util.AsyncProcessorHelper.process(AsyncProcessorHelper.java:105)
at org.apache.camel.component.bean.BeanProcessor.process(BeanProcessor.java:67)
at     org.apache.camel.language.bean.BeanExpression$InvokeProcessor.process(BeanExpression.java:1    89)
at org.apache.camel.language.bean.BeanExpression.evaluate(BeanExpression.java:123)
at org.apache.camel.language.bean.BeanExpression.matches(BeanExpression.java:137)
at org.apache.camel.processor.ChoiceProcessor.process(ChoiceProcessor.java:90)
at org.apache.camel.management.InstrumentationProcessor.process(InstrumentationProcessor.java:    72)
at org.apache.camel.processor.RedeliveryErrorHandler.process(RedeliveryErrorHandler.java:398)
at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:191)
at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:191)
at org.apache.camel.util.AsyncProcessorHelper.process(AsyncProcessorHelper.java:105)
at org.apache.camel.processor.DelegateAsyncProcessor.process(DelegateAsyncProcessor.java:87)
at     org.apache.camel.component.jms.EndpointMessageListener.onMessage(EndpointMessageListener.ja    va:103)
at org.springframework.jms.listener.AbstractMessageListenerContainer.doInvokeListener(Abstract    MessageListenerContainer.java:562)
at org.springframework.jms.listener.AbstractMessageListenerContainer.invokeListener(AbstractMe    ssageListenerContainer.java:500)
at org.springframework.jms.listener.AbstractMessageListenerContainer.doExecuteListener(Abstrac    tMessageListenerContainer.java:468)
at org.springframework.jms.listener.AbstractPollingMessageListenerContainer.doReceiveAndExecut    e(AbstractPollingMessageListenerContainer.java:325)
at org.springframework.jms.listener.AbstractPollingMessageListenerContainer.receiveAndExecute(    AbstractPollingMessageListenerContainer.java:263)
at org.springframework.jms.listener.DefaultMessageListenerContainer$AsyncMessageListenerInvoke    r.invokeListener(DefaultMessageListenerContainer.java:1102)
at org.springframework.jms.listener.DefaultMessageListenerContainer$AsyncMessageListenerInvoke    r.executeOngoingLoop(DefaultMessageListenerContainer.java:1094)
at org.springframework.jms.listener.DefaultMessageListenerContainer$AsyncMessageListenerInvoke    r.run(DefaultMessageListenerContainer.java:991)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
WARN : org.apache.camel.component.jms.EndpointMessageListener - Execution of JMS     message     listener failed. Caused by: [org.apache.camel.RuntimeCamelException -         java.lang.NullPointerException]
org.apache.camel.RuntimeCamelException: java.lang.NullPointerException
at org.apache.camel.util.ObjectHelper.wrapRuntimeCamelException(ObjectHelper.java:1363)
at     org.apache.camel.component.jms.EndpointMessageListener$EndpointMessageListenerAsyncCallback    .done(EndpointMessageListener.java:186)
at org.apache.camel.component.jms.EndpointMessageListener.onMessage(EndpointMessageListener.ja    va:107)
at org.springframework.jms.listener.AbstractMessageListenerContainer.doInvokeListener(Abstract    MessageListenerContainer.java:562)
at org.springframework.jms.listener.AbstractMessageListenerContainer.invokeListener(AbstractMe    ssageListenerContainer.java:500)
at org.springframework.jms.listener.AbstractMessageListenerContainer.doExecuteListener(Abstrac    tMessageListenerContainer.java:468)
at org.springframework.jms.listener.AbstractPollingMessageListenerContainer.doReceiveAndExecut    e(AbstractPollingMessageListenerContainer.java:325)
at org.springframework.jms.listener.AbstractPollingMessageListenerContainer.receiveAndExecute(    AbstractPollingMessageListenerContainer.java:263)
at org.springframework.jms.listener.DefaultMessageListenerContainer$AsyncMessageListenerInvoke    r.invokeListener(DefaultMessageListenerContainer.java:1102)
at org.springframework.jms.listener.DefaultMessageListenerContainer$AsyncMessageListenerInvoke    r.executeOngoingLoop(DefaultMessageListenerContainer.java:1094)
at org.springframework.jms.listener.DefaultMessageListenerContainer$AsyncMessageListenerInvoke    r.run(DefaultMessageListenerContainer.java:991)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.NullPointerException
at com.routing.integration.modifier.adder(modifier.java:19)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.apache.camel.component.bean.MethodInfo.invoke(MethodInfo.java:407)
at org.apache.camel.component.bean.MethodInfo$1.doProceed(MethodInfo.java:278)
at org.apache.camel.component.bean.MethodInfo$1.proceed(MethodInfo.java:251)
at org.apache.camel.component.bean.BeanProcessor.process(BeanProcessor.java:166)
at org.apache.camel.util.AsyncProcessorHelper.process(AsyncProcessorHelper.java:105)
at org.apache.camel.component.bean.BeanProcessor.process(BeanProcessor.java:67)
at org.apache.camel.language.bean.BeanExpression$InvokeProcessor.process(BeanExpression.java:1    89)
at org.apache.camel.language.bean.BeanExpression.evaluate(BeanExpression.java:123)
at org.apache.camel.language.bean.BeanExpression.matches(BeanExpression.java:137)
at org.apache.camel.processor.ChoiceProcessor.process(ChoiceProcessor.java:90)
at org.apache.camel.management.InstrumentationProcessor.process(InstrumentationProcessor.java:    72)
at org.apache.camel.processor.RedeliveryErrorHandler.process(RedeliveryErrorHandler.java:398)
at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:191)
at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:191)
at org.apache.camel.util.AsyncProcessorHelper.process(AsyncProcessorHelper.java:105)
at org.apache.camel.processor.DelegateAsyncProcessor.process(DelegateAsyncProcessor.java:87)
at org.apache.camel.component.jms.EndpointMessageListener.onMessage(EndpointMessageListener.ja    va:103)
... 11 more

编辑 2

这是调用 ComponentScan 的主类:

package hello;

import org.apache.camel.ProducerTemplate;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.support.ClassPathXmlApplicationContext;

@Configuration
@EnableAutoConfiguration
@ComponentScan(basePackages = {"hello", "com.routing.integration"})
public class Application {
    static ApplicationContext context = null;
    static ProducerTemplate camelTemplate = null;
    public static void main(String[] args) {

        SpringApplication.run(Application.class, args);
        System.out.println("----------------------\nSpringBootComplete\n----------------------");
        startBody("startup");
    }

    public static void startBody(String message) {
        if (context == null) {
            context = new ClassPathXmlApplicationContext("camelspring.xml");
            camelTemplate = context.getBean("camelTemplate", ProducerTemplate.class);
        }
        if (message != "startup"){
            camelTemplate.sendBody("activemq:queue:testQSource", message);
        }
    }           
}

最佳答案

您的 Application 类应该如下所示:

@Configuration
@ComponentScan(basePackages = {"hello", "com.routing.integration"})
@EnableAutoConfiguration
@ImportResource("classpath:camel.xml")
public class Application {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

camel.xml 是包含您的 camel 定义的 xml 配置文件。 如果您需要在 xml 配置中定义的任何 bean，例如 xml 中的 camelTemplate，您可以像这样获取它的引用，例如:

package hello;

import javax.annotation.Resource;

import org.apache.camel.ProducerTemplate;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class MyController {

    @Resource(name="camelTemplate")
    private ProducerTemplate template;

    @RequestMapping("/")
    String home() {
        System.out.println(template);
        return "Hello World!";
    }
}

正如我在评论中所说，不要手动创建应用上下文。使用@Component、@Service、@Configuration 和@Bean 等注册你想要的bean。如果你需要在 Java 代码中难以重现的 xml 配置，请使用 @ImportResource。

在您拥有的 xml 配置文件中，您可以将 browserBean bean 替换为放置在 hello.HelloController 类上的 @Controller 注释。

您的 activemq bean 可以在 Java Config 中转换成类似这样的东西:

@Configuration
public class Config {

    @Bean
    public ActiveMQComponent activemq() {
        ActiveMQComponent comp = new ActiveMQComponent();
        comp.setBrokerUrl("tcp://localhost:61616");

        return comp;
    }
}

关于java - @Autowire 调用期间未实例化服务类，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/24763580/

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