@Value和@Autowired在Azure函数中不起作用

问题描述

我正在Azure函数中编写@TimerTrigger函数。为此，我将Spring Cloud Function用于Azure。问题是，每次访问Service或JPARepository时，我都会得到一个空指针异常。另外@Value（“ $ {VARIABLE}”）给出null，但System.getenv（“ VARIABLE”）确实提供了值。

Main.Java代码为：

@SpringBootApplication
@EnableJpaRepositories("com.xyz.*")
@ComponentScan(basePackages = "com.xyz.*")
@EntityScan("com.xyz.*")
public class Scheduler {

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

    @Bean
    public void hello() {}
}

函数HelloHandler.java文件是：

@Component
public class HelloHandler extends AzureSpringBootRequestHandler<Void,Void> {

    @Autowired
    MyService myService;

    @Value("${VARIABLE}")
    private String variable;

    @FunctionName("hello")
    public void execute(@TimerTrigger(name = "timerInfo",schedule = "0 * * * * *") String timerInfo,final ExecutionContext context){
        context.getLogger().info("Executing the function..."+variable);    // this gives null.
        context.getLogger().info(System.getenv("VARIABLE"));               // this does provide value.
        myService.hello(context);                                          // null pointer exception here.
        context.getLogger().info("Here I am...");
    }
}

Service MyService.Java是：

@Service
public class MyServiceImpl implements MyService {

    @Autowired
    private MyRepository myRepository;

    public void hello(ExecutionContext context) {
        List<User> userList = myRepository.findAll();
        for (User user : userList) {
            context.getLogger().info("USER: "+user.getId());
        }

        context.getLogger().info("Process Finished.");
    }
}

我正在使用以下依赖项：

        <!-- https://mvnrepository.com/artifact/org.springframework.cloud/spring-cloud-function-adapter-azure -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-function-adapter-azure</artifactId>
            <version>2.0.1.RELEASE</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.springframework.cloud/spring-cloud-starter-function-web -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-function-web</artifactId>
            <version>2.0.1.RELEASE</version>
        </dependency>

它给出例外：

Executed 'Functions.hello' (Failed,Id=90714488-b07a-41ac-ae37-d120a1a8e732,Duration=372ms)
System.Private.CoreLib: Exception while executing function: Functions.hello. System.Private.CoreLib: Result: Failure
Exception: NullPointerException: 
Stack: java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.microsoft.azure.functions.worker.broker.JavaMethodInvokeInfo.invoke(JavaMethodInvokeInfo.java:22)
    at com.microsoft.azure.functions.worker.broker.JavaMethodExecutorImpl.execute(JavaMethodExecutorImpl.java:54)
    at com.microsoft.azure.functions.worker.broker.JavaFunctionbroker.invokeMethod(JavaFunctionbroker.java:57)
    at com.microsoft.azure.functions.worker.handler.InvocationRequestHandler.execute(InvocationRequestHandler.java:33)
    at com.microsoft.azure.functions.worker.handler.InvocationRequestHandler.execute(InvocationRequestHandler.java:10)
    at com.microsoft.azure.functions.worker.handler.MessageHandler.handle(MessageHandler.java:45)
    at com.microsoft.azure.functions.worker.JavaWorkerClient$StreamingMessagePeer.lambda$onNext$0(JavaWorkerClient.java:92)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.NullPointerException
    at com.xyz.scheduler.HelloHandler.execute(HelloHandler.java:26)
    ... 16 more
.

我不明白为什么它不能按预期使用所有Spring功能。

解决方法

不确定为什么它不起作用，它看起来正确。我在演示中同时尝试了@Value和System.getenv()，它们运行良好。

如果在环境变量中找不到键（ VARIABLE ），则会出现此异常 java.lang.IllegalArgumentException：无法解析字符串值“ $ {XXX}”中的占位符'XXX'。。

因此，您的方法hello()中似乎出现了NullPointerException，请尝试逐步调试方法，可能会在user.getId()处发生。