Apache的骆驼和弹簧引导构造注射 - NPE

问题描述：

我有以下简单的弹簧，启动应用程序，它使用了Apache的骆驼：Apache的骆驼和弹簧引导构造注射 - NPE

DemoApplication.java：

@SpringBootApplication 
public class DemoApplication { 

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

@Component 
class MySampleRoute extends SpringRouteBuilder { 

    @Override 
    public void configure() throws Exception { 
     from("file://data/input") 
       .bean(SampleProcessor1.class) 
       .to("file://data/output"); 
    } 
}

而且我的豆子：

SampleProcessor1.java：

public class SampleProcessor1 { 

    private SampleProcessor2 sampleProcessor2; 

    @Autowired 
    public SampleProcessor1(SampleProcessor2 sampleProcessor2) { 
     this.sampleProcessor2 = sampleProcessor2; 
    } 

    @Handler 
    public void handle(
      @Body GenericFile<String> file 
    ) { 

    } 
}

SampleProcessor2.java：

@Component 
public class SampleProcessor2 { }

当我运行该应用程序，并把一些文件data/input目录 - 我得到以下NPE：

java.lang.NullPointerException: null 
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_111] 
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_111] 
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_111] 
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_111] 
at org.apache.camel.component.bean.MethodInfo.invoke(MethodInfo.java:472) ~[camel-core-2.19.3.jar:2.19.3] 
at org.apache.camel.component.bean.MethodInfo$1.doProceed(MethodInfo.java:291) ~[camel-core-2.19.3.jar:2.19.3] 
at org.apache.camel.component.bean.MethodInfo$1.proceed(MethodInfo.java:264) ~[camel-core-2.19.3.jar:2.19.3] 
at org.apache.camel.component.bean.BeanProcessor.process(BeanProcessor.java:178) ~[camel-core-2.19.3.jar:2.19.3] 
at org.apache.camel.management.InstrumentationProcessor.process(InstrumentationProcessor.java:77) ~[camel-core-2.19.3.jar:2.19.3] 
at org.apache.camel.processor.RedeliveryErrorHandler.process(RedeliveryErrorHandler.java:541) ~[camel-core-2.19.3.jar:2.19.3] 
at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:198) [camel-core-2.19.3.jar:2.19.3] 
at org.apache.camel.processor.Pipeline.process(Pipeline.java:120) [camel-core-2.19.3.jar:2.19.3] 
at org.apache.camel.processor.Pipeline.process(Pipeline.java:83) [camel-core-2.19.3.jar:2.19.3] 
at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:198) [camel-core-2.19.3.jar:2.19.3] 
at org.apache.camel.component.file.GenericFileConsumer.processExchange(GenericFileConsumer.java:451) [camel-core-2.19.3.jar:2.19.3] 
at org.apache.camel.component.file.GenericFileConsumer.processBatch(GenericFileConsumer.java:218) [camel-core-2.19.3.jar:2.19.3] 
at org.apache.camel.component.file.GenericFileConsumer.poll(GenericFileConsumer.java:182) [camel-core-2.19.3.jar:2.19.3] 
at org.apache.camel.impl.ScheduledPollConsumer.doRun(ScheduledPollConsumer.java:174) [camel-core-2.19.3.jar:2.19.3] 
at org.apache.camel.impl.ScheduledPollConsumer.run(ScheduledPollConsumer.java:101) [camel-core-2.19.3.jar:2.19.3] 
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [na:1.8.0_111] 
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308) [na:1.8.0_111] 
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180) [na:1.8.0_111] 
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294) [na:1.8.0_111] 
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_111] 
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_111] 
at java.lang.Thread.run(Thread.java:745) [na:1.8.0_111]

但是，如果我尝试从SampleProcessor1和使用删除构造函数注入，例如字段注入 - 那么没有NPE发生，一切都很好。

SampleProcessor1.java - 工作版本：

public class SampleProcessor1 { 

    @Autowired 
    private SampleProcessor2 sampleProcessor2; 

    @Handler 
    public void handle(
      @Body GenericFile<String> file 
    ) { 

    } 
}

按照我的理解 - 这个问题是在构造函数注入 - 但我不明白为什么。

所以我的问题是为什么我使用构造函数注入时获得NPE？

我用spring-boot:1.5.7.RELEASE 和org.apache.camel:camel-spring-boot-starter:2.19.3

更新1：添加的源代码的github：Repository on github

更新2：

新增断点NPE发生的方法之前：

随着构造器注入：

没有构造函数注入（使用字段注入）：

声明它请发布您的POM或Gradle文件。如果你可以设置一个断点并找出骆驼想要调用的方法，这也会很有帮助。 – chrylis

请参阅更新，将源代码添加到github – Vusal

答

弹簧构造函数注入不能在骆驼2.19.x或以上支持。您需要升级到骆驼2.20.0或更新版本。

参阅发行说明：http://camel.apache.org/camel-2200-release.html

使用骆驼和Spring现在支持调用的Bean的FQN的名字，让春季使用自动布线构造的，而不是只支持一个无参数的构造函数实例化的bean。

另一种方法是指豆与豆ID，让通过

.bean("mySampleProcessor")

春天更多地管理它，然后在课堂上，你用这个名字

@Component("mySampleProcessor") 
public class SampleProcessor1 { 
    ... 
}

Apache的骆驼和弹簧引导构造注射 - NPE

相关推荐