默认值为 @Value 处的持续时间

Question

我需要为java.time.Duration类型的实例变量指定默认值

我传递的默认值被读取为字符串，导致 IllegalStateException

我的课

public class Test {
  @Value("${kafka.consumer.commit.interval:5s}")
  private Duration commitInterval;

  .
  .
  .

}

例外：

  Unsatisfied dependency expressed through field 'commitInterval'; 
  nested exception is org.springframework.beans.ConversionNotSupportedException: Failed to convert value of type 'java.lang.String' to required type 'java.time.Duration'; 
  nested exception is java.lang.IllegalStateException: Cannot convert value of type 'java.lang.String' to required type 'java.time.Duration': no matching editors or conversion strategy found

Answer 1

您可以直接使用 SpEL 表达式来调用Duration类的工厂方法：

@Value("${kafka.consumer.commit.interval:#{T(java.time.Duration).of(5, T(java.time.temporal.ChronoUnit).SECONDS)}}")
private Duration commitInterval;

然而正如你所看到的，它有点冗长。或者像评论中提到的OP更简单的版本：

@Value("${kafka.consumer.commit.interval:#{T(java.time.Duration).ofSeconds(5)}}")
private Duration commitInterval;