java - 仅当 bean 作为方法参数存在时，Spring 才会 Autowiring

Question

我正在使用 @ConditionalOnProperty 创建一个 FileCompressor bean:

@Bean
@ConditionalOnProperty(prefix = "file.rollover.sink", name = "compress", matchIfMissing = true)
public FileCompressor fileCompressor() {
    return new DefaultFileCompressor(...);
}

我想仅在 FileCompressor bean 存在时 Autowiring 它，null 如果 file.rollover.sink.compress=false 作为方法参数。 但是，如果我尝试将其定义为:

@Bean
public RolloverTask rolloverTask(final IntervalCalculator intervalCalculator, final @Autowired(required = false) FileCompressor fileCompressor) {
    return new RolloverTask(intervalCalculator, fileCompressor);
}

我收到以下错误:

Parameter 1 of method rolloverTask in com.example.FileRolloverSinkConfiguration required a bean of type 'com.example.compressor.FileCompressor' that could not be found.
    - Bean method 'fileCompressor' in 'FileRolloverSinkConfiguration' not loaded because @ConditionalOnProperty (file.rollover.sink.compress) found different value in property 'compress'

如果不存在，我应该对 Autowiring 或传递 null 进行哪些更改？

-- 编辑--

我的解决方案:

private FileCompressor fileCompressor;

@Autowired(required = false)
public void setFileCompressor(final FileCompressor fileCompressor) {
    this.fileCompressor = fileCompressor;
}


@Bean
public RolloverTask rolloverTask(final IntervalCalculator intervalCalculator) {
        log.info("Creating a new rollover task with{} a file compressor", fileCompressor == null ? "out" : "");
        return new RolloverTask(intervalCalculator, fileCompressor);
}

@Bean
@ConditionalOnProperty(prefix = "file.rollover.sink", name = "compress", matchIfMissing = true)
public FileCompressor fileCompressor() {
    return new DefaultFileCompressor(...);
}

Answer 1

我认为你可以使用注释 @ConditionalOnBean 和 @ConditionalOnMissingBean

我没有尝试代码，但它应该是这样的:

@Bean
@ConditionalOnBean(FileCompressor.class)
public RolloverTask rolloverTask(final IntervalCalculator intervalCalculator, final FileCompressor fileCompressor) {
    return new RolloverTask(intervalCalculator, fileCompressor);
}

和

@Bean
@ConditionalOnMissingBean(FileCompressor.class)
public RolloverTask rolloverTask(final IntervalCalculator intervalCalculator) {
    return new RolloverTask(intervalCalculator, null);
}