仅当 bean 作为方法参数存在时 Spring 自动装配

Question

我用来@ConditionalOnProperty创建一个FileCompressorbean：

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

我想FileCompressor仅在 bean 存在时（null如果file.rollover.sink.compress=false作为方法参数）自动装配 bean。但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'

null如果不存在，我应该对自动装配或传递进行哪些更改？

- 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

matchIfMissing = true有没有没有意义havingValue =。因为如果您没有属性，则会创建 bean，如果您有一个具有任何值的属性，则会创建 bean。

你可以这样解决：

    @Autowired(required = false)
    private FileCompressor fileCompressor;

    @Bean
    public RolloverTask rolloverTaskWithCompressor(final IntervalCalculator intervalCalculator, final FileCompressor fileCompressor) {
        return new RolloverTask(intervalCalculator, fileCompressor);
   }

或者对两个版本有不同的 bean 定义RolloverTask：

    @Bean
    @ConditionalOnProperty(prefix = "file.rollover.sink", name = "compress", havingValue = "no", matchIfMissing = false)
    public RolloverTask rolloverTask(IntervalCalculator intervalCalculator) {
        return new RolloverTask(intervalCalculator, null);
    }

    @Bean
    @ConditionalOnProperty(prefix = "file.rollover.sink", name = "compress", havingValue = "yes", matchIfMissing = true)
    public RolloverTask rolloverTaskWithCompressor(final IntervalCalculator intervalCalculator, final FileCompressor fileCompressor) {
        return new RolloverTask(intervalCalculator, fileCompressor);
   }