尝试从 aws lambda 处理函数调用 SDN 时出现 java.lang.NullPointerException

Question

我有一个处理程序函数，在其中调用我的 Spring 数据存储库接口(interface)。该代码在我的 main 方法或 jar 中运行良好，但当我在 s3 中上传 jar 并从调用存储库方法的 aws lambda 调用时，会抛出 NullPointerException 。下面是我的 lambda 处理程序方法；

public class LambdaRestFunction implements RequestHandler<String, Object> {

    @Autowired
    UserRepository userRepository;

    @Override
    public String handleRequest(String uname, Context context) {
        String time = new SimpleDateFormat("yyyy-MM-dd_HH:mm:ss").format(Calendar.getInstance().getTime());

        context.getLogger().log("Lambda call started: " + time);

        List<User> users = new ArrayList<>();
        context.getLogger().log("Array initialized.");
        **users = userRepository.findByName(uname);** // <-- NullPointerException thrown here
        context.getLogger().log("Method call over..");
        ObjectWriter ow = new ObjectMapper().writer().withDefaultPrettyPrinter();
        String json = "[]";
        try {
            json = ow.writeValueAsString(users);
        } catch (JsonProcessingException e) {
            e.printStackTrace();
            context.getLogger().log("Error from application : " + e.getMessage());
        }

        context.getLogger().log("Lambda function completed: " + time);
        return json;
    }

}

我的存储库界面是；

@RepositoryRestResource(collectionResourceRel = "user", path = "user")
public interface UserRepository extends GraphRepository<User> { 
    @Query("MATCH (u:User) WHERE u.id =({id}) RETURN u")
    User findUser(@Param("id") Long id);    
}

域类是；

@NodeEntity
public class User {

    @GraphId Long id;
    private String name;
    private String dob;
    private String cc;

    public User(String name, String dob, String cc) {
        this.name = name;
        this.dob = dob;
        this.cc = cc;
    }

    public User() {
    }

    public String getName() {
        return name;
    }
...

请在下面找到跟踪日志:

java.lang.NullPointerException
at com.test.lambda.LambdaRestFunction.handleRequest(LambdaRestFunction.java:36)
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 lambdainternal.EventHandlerLoader$PojoMethodRequestHandler.handleRequest(EventHandlerLoader.java:439)
at lambdainternal.EventHandlerLoader$PojoHandlerAsStreamHandler.handleRequest(EventHandlerLoader.java:370)
at lambdainternal.EventHandlerLoader$2.call(EventHandlerLoader.java:972)
at lambdainternal.AWSLambda.startRuntime(AWSLambda.java:235)
at lambdainternal.AWSLambda.<clinit>(AWSLambda.java:60)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:348)
at lambdainternal.LambdaRTEntry.main(LambdaRTEntry.java:94) 

如果有人能帮助我找到异常的原因，我将非常感激。预先感谢您。

Answer 1

Lambda不支持注解，因此@Autowired不会达到预期的效果。

在https://docs.aws.amazon.com/lambda/latest/dg/java-programming-model-req-resp.html ，请参阅“处理程序输入/输出:POJO 类型”下的注释。