java - 处理 Spring 集成文件的预期返回

Question

我有以下 Spring 集成文件配置文件:

@Configuration
@EnableIntegration
public class MyIntegrationConfiguration {

    private static final String FILE_CHANNEL_PROCESSING = "processingfileChannel";
    private static final String INTERVAL_PROCESSING = "5000";
    private static final String FILE_PATTERN = "*.txt";

    @Value("${import.path.source}")
    private String sourceDir;

    @Value("${import.path.output}")
    private String outputDir;

    @Bean
    @InboundChannelAdapter(value = FILE_CHANNEL_PROCESSING, poller = @Poller(fixedDelay = INTERVAL_PROCESSING))
    public MessageSource<File> sourceFiles() {
        FileReadingMessageSource source = new FileReadingMessageSource();
        source.setAutoCreateDirectory(true);
        source.setDirectory(new File(sourceDir));
        source.setFilter(new SimplePatternFileListFilter(FILE_PATTERN));
        return source;
    }

    @Bean
    @ServiceActivator(inputChannel = FILE_CHANNEL_PROCESSING)
    public MessageHandler processedFiles() {
        FileWritingMessageHandler handler = new FileWritingMessageHandler(new File(outputDir));
        handler.setFileExistsMode(FileExistsMode.REPLACE);
        handler.setDeleteSourceFiles(true);
        handler.setExpectReply(true);
        return handler;
    }

    @Bean
    public IntegrationFlow processFileFlow() {
        return IntegrationFlows
            .from(FILE_CHANNEL_PROCESSING)
            .transform(fileToStringTransformer())
            .handle("fileProcessor", "processFile").get();
    }

    @Bean
    public MessageChannel fileChannel() {
        return new DirectChannel();
    }

    @Bean
    public FileProcessor fileProcessor() {
        return new FileProcessor();
    }

    @Bean
    public FileToStringTransformer fileToStringTransformer() {
        return new FileToStringTransformer();
    }
}

对于来自this documentation的FileWritingMessageHandler它表示如果设置了 setExpectReply(true):

Specify whether a reply Message is expected. If not, this handler will simply return null for a successful response or throw an Exception for a non-successful response.

我的问题是:我在哪里可以捕获这些异常或者在哪里可以检索此消息/响应？

Answer 1

@ServiceActivator有一个 outputChannel属性:

/**
 * Specify the channel to which this service activator will send any replies.
 * @return The channel name.
 */
String outputChannel() default "";

这是成功回复的结果。

任何异常(独立于 setExpectReply() )都会抛出给调用者。在你的例子中，这个故事是关于 @InboundChannelAdapter 。在这种情况下，异常被捕获并包装到 ErrorMessage发送至errorChannel关于@Poller 。这是全局errorChannel默认:https://docs.spring.io/spring-integration/docs/5.0.4.RELEASE/reference/html/configuration.html#namespace-errorhandler

但是您的代码中还存在其他问题。我看到 FILE_CHANNEL_PROCESSING 的第二个订阅者 。如果不是PublishSubscribeChannel ，您将对发送到此 channel 的消息进行循环分配。但这已经是一个不同的故事了。请不要在这里问这个问题!