英文:
@Validated annotation makes field of @ConfigurationProperties class to be null
问题
以下是翻译好的部分：
类 1:
@ConfigurationProperties
@Validated ֎ 1 ֎
public class SplitterProps {
@Valid
public final ConnectionParams connectionParams;
// @Valid
// @NotNull
public final Subscriber subscriber;
public final List<@NotNull @Valid Converter> converters;
@ConstructorBinding
public SplitterProps(ConnectionParams connectionParams,
Map<String, Subscriber> subscribersList,
List<Converter> converters) {
this.connectionParams = connectionParams;
this.subscriber = subscribersList.isEmpty() ?
null :
subscribersList.values().iterator().next();
this.converters = converters;
}
...
}
YAML 配置:
...
subscribersList:
sub1:
kafkaBroker: xxx:9092
topicName: saveTopic
healthCheckTimeout: 10
producerTimeout: 10
...
类 2:
@Configuration(proxyBeanMethods = false)
public class KafkaConfig {
private final Subscriber subscriberProps;
private final Map<String, Object> producerProps;
public KafkaConfig(KafkaProperties kafkaProps,
SplitterProps appProps) {
this.subscriberProps = appProps.subscriber; ֎ 2 ֎
this.producerProps = getProducerProperties(kafkaProps, subscriberProps);
}
...
}
如果在第 ֎ 1 ֎ 行有 @Validated 注解，
则在第 ֎ 2 ֎ 行，appProps.subscriber == null。（导致 NPE 错误）
如果在第 ֎ 1 ֎ 行没有 @Validated 注解，
则在第 ֎ 2 ֎ 行，appProps.subscriber != null。（按预期工作）
为什么会出现这种情况，以及如何避免？
英文:
I have the following two classes and yaml-config:
Class 1:
@ConfigurationProperties
@Validated ֎ 1 ֎
public class SplitterProps {
@Valid
public final ConnectionParams connectionParams;
// @Valid
// @NotNull
public final Subscriber subscriber;
public final List<@NotNull @Valid Converter> converters;
@ConstructorBinding
public SplitterProps(ConnectionParams connectionParams,
Map<String, Subscriber> subscribersList,
List<Converter> converters) {
this.connectionParams = connectionParams;
this.subscriber = subscribersList.isEmpty() ?
null :
subscribersList.values().iterator().next();
this.converters = converters;
}
...
}
YAML-config:
...
subscribersList:
sub1:
kafkaBroker: xxx:9092
topicName: saveTopic
healthCheckTimeout: 10
producerTimeout: 10
...
Class 2:
@Configuration(proxyBeanMethods = false)
public class KafkaConfig {
private final Subscriber subscriberProps;
private final Map<String, Object> producerProps;
public KafkaConfig(KafkaProperties kafkaProps,
SplitterProps appProps) {
this.subscriberProps = appProps.subscriber; ֎ 2 ֎
this.producerProps = getProducerProperties(kafkaProps, subscriberProps);
}
...
}
If there IS @Validated annotation in row ֎ 1 ֎
then appProps.subscriber == null in row ֎ 2 ֎. (NPE arised)
If there is NO @Validated annotation in row ֎ 1 ֎
then appProps.subscriber != null in row ֎ 2 ֎. (works as expected)
Why could it be and how to avoid it?
答案1
得分: 2
解决方案如下：
- 当在@ConfigurationProperties类上没有@Validate注解时，调用appProps.subscriber将引用SplitterProps类的实例。
- 当在@ConfigurationProperties类上有@Validate注解时，SplitterProps会包装成Spring代理，因此调用appProps.subscriber将引用代理成员。
为了处理这种行为，我应该通过getter执行字段访问。
因此，我已经在SplitterProps类上添加了@Getter，现在appProps.getSubscriber() != null。
英文:
Solution is the following:
- when there is no @Validate annotation on @ConfigurationProperties class
then calling appProps.subscriber refers to instance of SplitterProps class. - when there is @Validate annotation on @ConfigurationProperties class
then SplitterProps wraps into Spring proxy so calling appProps.subscriber refers to proxy member.
To handle this behavior I should perform field access via getter.
So I've added @Getter to SplitterProps class and now appProps.getSubscriber() != null.
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