无法在 Spring 集成中自动装配 MessageChannel

Question

我正在尝试使用 spring 集成的 FTP 文件上传和下载示例。我想手动将文件上传到 outputChannel。当 inputChannel 发生变化时，我不想调用它。因此，FTPApplication 应该只有一个 outputChannel bean 的声明。为此，我参考了这篇文章Uploading files directly to specific folder in ftp server using spring spring（仅用于手动上传，这种方式在大多数页面中都很常见）。下面是 Spring Boot 应用代码：

@SpringBootApplication
public class FtpApplication {

    public static void main(String[] args) {
        SpringApplication.run(FtpApplication.class, args);
    }

    @Bean
    public SessionFactory<FTPFile> ftpSessionFactory() {
        DefaultFtpSessionFactory sf = new DefaultFtpSessionFactory();
        sf.setHost("localhost");
        sf.setPort(21);
        sf.setUsername("root");
        sf.setPassword("root");
        return new CachingSessionFactory<FTPFile>(sf);
    }

    @Bean
    public FtpInboundFileSynchronizer ftpInboundFileSynchronizer() {
        FtpInboundFileSynchronizer fileSynchronizer = new FtpInboundFileSynchronizer(ftpSessionFactory());
        fileSynchronizer.setDeleteRemoteFiles(false);
        fileSynchronizer.setRemoteDirectory("/");
        fileSynchronizer.setFilter(new FtpSimplePatternFileListFilter("*.xml"));
        return fileSynchronizer;
    }

    @Bean
    @InboundChannelAdapter(value="inputChannel", channel = "inputChannel")
    public MessageSource<File> ftpMessageSource() {
        FtpInboundFileSynchronizingMessageSource source = new FtpInboundFileSynchronizingMessageSource(
                ftpInboundFileSynchronizer());
        source.setLocalDirectory(new File("ftp-inbound"));
        source.setAutoCreateLocalDirectory(true);
        source.setLocalFilter(new AcceptOnceFileListFilter<File>());
        return source;
    }

    @Bean
    @ServiceActivator(inputChannel = "inputChannel")
    public MessageHandler handler() {
        return new MessageHandler() {
            @Override
            public void handleMessage(Message<?> message) throws MessagingException {
                System.out.println(message.getPayload());
            }
        };
    }

    @Bean(name = PollerMetadata.DEFAULT_POLLER)
    public PollerMetadata defaultPoller() {
        PollerMetadata pollerMetadata = new PollerMetadata();
        pollerMetadata.setTrigger(new PeriodicTrigger(10));
        return pollerMetadata;
    }

    @Bean
    @InboundChannelAdapter(value="outputChannel", channel = "outputChannel")
    public MessageSource<File> ftpMessageSource1() {
        FtpInboundFileSynchronizingMessageSource source = new FtpInboundFileSynchronizingMessageSource(
                ftpInboundFileSynchronizer());
        source.setLocalDirectory(new File("ftp-outbound"));
        source.setAutoCreateLocalDirectory(true);
        source.setLocalFilter(new AcceptOnceFileListFilter<File>());
        return source;
    }

}

控制器代码如下图：

@RestController
public class FTPController {

    @Autowired
    MessageChannel outputChannel;

    @RequestMapping(value = "/ftpuploadtest", method = RequestMethod.GET)
    public void getM36Messages() {
        File file = new File("ftp.txt");
        Message<File> fileMessage = MessageBuilder.withPayload(file).build();
        outputChannel.send(fileMessage);
    }
}

当我运行应用程序时，我收到以下错误：

Description:
Field outputChannel in com.ftp.FTPController required a single bean, but 3 were found:
    - nullChannel: defined in null
    - errorChannel: defined in null
    - inputChannel: a programmatically registered singleton

Action:

Consider marking one of the beans as @Primary, updating the consumer to accept multiple beans, or using @Qualifier to identify the bean that should be consumed

请帮助解决这个问题。

Answer 1

首先，我认为您在outputChannel 组件方面犯了一些错误。

如果是关于上传，那么你必须使用@ServiceActivator 和FtpMessageHandler。

另一方面，对于此类问题，您必须为outputChannel 声明@Bean，并与@Autowired 一起，在FTPController 中添加@Qualifier("outputChannel")。

Answer 2

使用 @Qualifier 和 @Autowired 。并保持变量名称与 bean 名称相同。