我本来希望 ftp 同步机制更新更改的文件。但是，从我在这里看到的情况来看，只有在文件尚不存在时才会下载该文件。目前，即使时间戳/内容已更改，文件也不会保存在本地。

到目前为止，这是我的发现:

类org.springframework.integration.file.remote.synchronizer.AbstractInboundFileSynchronizer

@Override
    public void synchronizeToLocalDirectory(final File localDirectory) {
        final String remoteDirectory = this.remoteDirectoryExpression.getValue(this.evaluationContext, String.class);
        try {
            int transferred = this.remoteFileTemplate.execute(new SessionCallback<F, Integer>() {

                @Override
                public Integer doInSession(Session<F> session) throws IOException {
                    F[] files = session.list(remoteDirectory);
                    if (!ObjectUtils.isEmpty(files)) {
                        List<F> filteredFiles = filterFiles(files);
                        for (F file : filteredFiles) {
                            try {
                                if (file != null) {
                                    copyFileToLocalDirectory(
                                            remoteDirectory, file, localDirectory,
                                            session);
                                }
                            }
                            catch (RuntimeException e) {
                                if (AbstractInboundFileSynchronizer.this.filter instanceof ReversibleFileListFilter) {
                                    ((ReversibleFileListFilter<F>) AbstractInboundFileSynchronizer.this.filter)
                                            .rollback(file, filteredFiles);
                                }
                                throw e;
                            }
                            catch (IOException e) {
                                if (AbstractInboundFileSynchronizer.this.filter instanceof ReversibleFileListFilter) {
                                    ((ReversibleFileListFilter<F>) AbstractInboundFileSynchronizer.this.filter)
                                            .rollback(file, filteredFiles);
                                }
                                throw e;
                            }
                        }
                        return filteredFiles.size();
                    }
                    else {
                        return 0;
                    }
                }
            });
            if (this.logger.isDebugEnabled()) {
                this.logger.debug(transferred + " files transferred");
            }
        }
        catch (Exception e) {
            throw new MessagingException("Problem occurred while synchronizing remote to local directory", e);
        }
    }

过滤要下载的文件。我想使用 org.springframework.integration.ftp.filters.FtpPersistentAcceptOnceFileListFilter，它比较文件名和最后的修改日期。。 p>

然后它会调用 copyFileToLocalDirectory 函数来过滤文件(要复制)。

protected void copyFileToLocalDirectory(String remoteDirectoryPath, F remoteFile, File localDirectory,
            Session<F> session) throws IOException {
        String remoteFileName = this.getFilename(remoteFile);
        String localFileName = this.generateLocalFileName(remoteFileName);
        String remoteFilePath = remoteDirectoryPath != null
                ? (remoteDirectoryPath + this.remoteFileSeparator + remoteFileName)
                : remoteFileName;
        if (!this.isFile(remoteFile)) {
            if (this.logger.isDebugEnabled()) {
                this.logger.debug("cannot copy, not a file: " + remoteFilePath);
            }
            return;
        }

        File localFile = new File(localDirectory, localFileName);
        if (!localFile.exists()) {
            String tempFileName = localFile.getAbsolutePath() + this.temporaryFileSuffix;
            File tempFile = new File(tempFileName);
            OutputStream outputStream = new BufferedOutputStream(new FileOutputStream(tempFile));
            try {
                session.read(remoteFilePath, outputStream);
            }
            catch (Exception e) {
                if (e instanceof RuntimeException) {
                    throw (RuntimeException) e;
                }
                else {
                    throw new MessagingException("Failure occurred while copying from remote to local directory", e);
                }
            }
            finally {
                try {
                    outputStream.close();
                }
                catch (Exception ignored2) {
                }
            }

            if (tempFile.renameTo(localFile)) {
                if (this.deleteRemoteFiles) {
                    session.remove(remoteFilePath);
                    if (this.logger.isDebugEnabled()) {
                        this.logger.debug("deleted " + remoteFilePath);
                    }
                }
            }
            if (this.preserveTimestamp) {
                localFile.setLastModified(getModified(remoteFile));
            }
        }
    }

但是，此方法会检查(仅基于文件名)文件是否已存在于本地磁盘上，并且仅在不存在时才下载。所以基本上没有机会下载带有(带有新时间戳)的更新文件。

我试过尝试更改 FtpInboundFileSynchronizer，但它变得太复杂了。 “定制”synchronize-/copyToLocalDirectory 方法的最佳方式是什么？

最佳答案

可以更新 AbstractInboundFileSynchronizer 以识别更新的文件，但它很脆弱，您会遇到其他问题。

2016 年 11 月 13 日更新:了解如何在几秒钟内获取修改时间戳。

更新 AbstractInboundFileSynchronizer 的主要问题是它有 setter 方法但没有( protected )getter 方法。如果将来 setter 方法做了一些聪明的事情，这里介绍的更新版本将会崩溃。

在本地目录中更新文件的主要问题是并发性:如果您在接收更新的同时处理本地文件，您可能会遇到各种麻烦。简单的方法是将本地文件移动到(临时)处理目录，以便可以将更新作为新文件接收，从而无需更新 AbstractInboundFileSynchronizer。另见 Camel 的时间戳 remarks .

默认情况下，FTP 服务器以分钟为单位提供修改时间戳。为了测试，我更新了 FTP 客户端以使用 MLSD命令以秒为单位提供修改时间戳(如果幸运的话，可以提供毫秒)，但并非所有 FTP 服务器都支持此功能。

如 Spring FTP reference 中所述本地文件过滤器需要是 FileSystemPersistentAcceptOnceFileListFilter 以确保在修改时间戳更改时选择本地文件。

下面是我更新的 AbstractInboundFileSynchronizer 版本，后面是我使用的一些测试类。

public class FtpUpdatingFileSynchronizer extends FtpInboundFileSynchronizer {

    protected final Log logger = LogFactory.getLog(this.getClass());

    private volatile Expression localFilenameGeneratorExpression;
    private volatile EvaluationContext evaluationContext;
    private volatile boolean deleteRemoteFiles;
    private volatile String remoteFileSeparator = "/";
    private volatile boolean  preserveTimestamp;

    public FtpUpdatingFileSynchronizer(SessionFactory<FTPFile> sessionFactory) {
        super(sessionFactory);
        setPreserveTimestamp(true);
    }

    @Override
    public void setLocalFilenameGeneratorExpression(Expression localFilenameGeneratorExpression) {
        super.setLocalFilenameGeneratorExpression(localFilenameGeneratorExpression);
        this.localFilenameGeneratorExpression = localFilenameGeneratorExpression;
    }

    @Override
    public void setIntegrationEvaluationContext(EvaluationContext evaluationContext) {
        super.setIntegrationEvaluationContext(evaluationContext);
        this.evaluationContext = evaluationContext;
    }

    @Override
    public void setDeleteRemoteFiles(boolean deleteRemoteFiles) {
        super.setDeleteRemoteFiles(deleteRemoteFiles);
        this.deleteRemoteFiles = deleteRemoteFiles;
    }

    @Override
    public void setRemoteFileSeparator(String remoteFileSeparator) {
        super.setRemoteFileSeparator(remoteFileSeparator);
        this.remoteFileSeparator = remoteFileSeparator;
    }

    @Override
    public void setPreserveTimestamp(boolean preserveTimestamp) {
        // updated
        Assert.isTrue(preserveTimestamp, "for updating timestamps must be preserved");
        super.setPreserveTimestamp(preserveTimestamp);
        this.preserveTimestamp = preserveTimestamp;
    }

    @Override
    protected void copyFileToLocalDirectory(String remoteDirectoryPath, FTPFile remoteFile, File localDirectory,
            Session<FTPFile> session) throws IOException {

        String remoteFileName = this.getFilename(remoteFile);
        String localFileName = this.generateLocalFileName(remoteFileName);
        String remoteFilePath = (remoteDirectoryPath != null
                ? (remoteDirectoryPath + this.remoteFileSeparator + remoteFileName)
                        : remoteFileName);

        if (!this.isFile(remoteFile)) {
            if (this.logger.isDebugEnabled()) {
                this.logger.debug("cannot copy, not a file: " + remoteFilePath);
            }
            return;
        }

        // start update
        File localFile = new File(localDirectory, localFileName);
        boolean update = false;
        if (localFile.exists()) {
            if (this.getModified(remoteFile) > localFile.lastModified()) {
                this.logger.info("Updating local file " + localFile);
                update = true;
            } else {
                this.logger.info("File already exists: " + localFile);
                return;
            }
        }
        // end update

        String tempFileName = localFile.getAbsolutePath() + this.getTemporaryFileSuffix();
        File tempFile = new File(tempFileName);
        OutputStream outputStream = new BufferedOutputStream(new FileOutputStream(tempFile));
        try {
            session.read(remoteFilePath, outputStream);
        } catch (Exception e) {
            if (e instanceof RuntimeException) {
                throw (RuntimeException) e;
            }
            else {
                throw new MessagingException("Failure occurred while copying from remote to local directory", e);
            }
        } finally {
            try {
                outputStream.close();
            }
            catch (Exception ignored2) {
            }
        }
        // updated
        if (update && !localFile.delete()) {
            throw new MessagingException("Unable to delete local file [" + localFile + "] for update.");
        }
        if (tempFile.renameTo(localFile)) {
            if (this.deleteRemoteFiles) {
                session.remove(remoteFilePath);
                if (this.logger.isDebugEnabled()) {
                    this.logger.debug("deleted " + remoteFilePath);
                }
            }
            // updated
            this.logger.info("Stored file locally: " + localFile);
        } else {
            // updated
            throw new MessagingException("Unable to rename temporary file [" + tempFile + "] to [" + localFile + "]");
        }
        if (this.preserveTimestamp) {
            localFile.setLastModified(getModified(remoteFile));
        }
    }

    private String generateLocalFileName(String remoteFileName) {

        if (this.localFilenameGeneratorExpression != null) {
            return this.localFilenameGeneratorExpression.getValue(this.evaluationContext, remoteFileName, String.class);
        }
        return remoteFileName;
    }

}

遵循我使用的一些测试类。 我使用了依赖项 org.springframework.integration:spring-integration-ftp:4.3.5.RELEASE 和 org.apache.ftpserver:ftpserver-core:1.0.6 (加上通常的日志记录和测试依赖项)。

public class TestFtpSync {

    static final Logger log = LoggerFactory.getLogger(TestFtpSync.class);
    static final String FTP_ROOT_DIR = "target" + File.separator + "ftproot";
    // org.apache.ftpserver:ftpserver-core:1.0.6
    static FtpServer server;

    @BeforeClass
    public static void startServer() throws FtpException {

        File ftpRoot = new File (FTP_ROOT_DIR);
        ftpRoot.mkdirs();
        TestUserManager userManager = new TestUserManager(ftpRoot.getAbsolutePath());
        FtpServerFactory serverFactory = new FtpServerFactory();
        serverFactory.setUserManager(userManager);
        ListenerFactory factory = new ListenerFactory();
        factory.setPort(4444);
        serverFactory.addListener("default", factory.createListener());
        server = serverFactory.createServer();
        server.start();
    }

    @AfterClass
    public static void stopServer() {

        if (server != null) {
            server.stop();
        }
    }

    File ftpFile = Paths.get(FTP_ROOT_DIR, "test1.txt").toFile();
    File ftpFile2 = Paths.get(FTP_ROOT_DIR, "test2.txt").toFile();

    @Test
    public void syncDir() {

        // org.springframework.integration:spring-integration-ftp:4.3.5.RELEASE
        AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
        try {
            ctx.register(FtpSyncConf.class);
            ctx.refresh();
            PollableChannel msgChannel = ctx.getBean("inputChannel", PollableChannel.class);
            for (int j = 0; j < 2; j++) {
                for (int i = 0; i < 2; i++) {
                    storeFtpFile();
                }
                for (int i = 0; i < 4; i++) {
                    fetchMessage(msgChannel);
                }
            }
        } catch (Exception e) {
            throw new AssertionError("FTP test failed.", e);
        } finally {
            ctx.close();
            cleanup();
        }
    }

    boolean tswitch = true;

    void storeFtpFile() throws IOException, InterruptedException {

        File f = (tswitch ? ftpFile : ftpFile2);
        tswitch = !tswitch;
        log.info("Writing message " + f.getName());
        Files.write(f.toPath(), ("Hello " + System.currentTimeMillis()).getBytes());
    }

    Message<?> fetchMessage(PollableChannel msgChannel) {

        log.info("Fetching message.");
        Message<?> msg = msgChannel.receive(1000L);
        if (msg == null) {
            log.info("No message.");
        } else {
            log.info("Have a message: " + msg);
        }
        return msg;
    }

    void cleanup() {

        delFile(ftpFile);
        delFile(ftpFile2);
        File d = new File(FtpSyncConf.LOCAL_DIR);
        if (d.isDirectory()) {
            for (File f : d.listFiles()) {
                delFile(f);
            }
        }
        log.info("Finished cleanup");
    }

    void delFile(File f) {

        if (f.isFile()) {
            if (f.delete()) {
                log.info("Deleted " + f);
            } else {
                log.error("Cannot delete file " + f);
            }
        }
    }

}

public class MlistFtpSessionFactory extends AbstractFtpSessionFactory<MlistFtpClient> {

    @Override
    protected MlistFtpClient createClientInstance() {
        return new MlistFtpClient();
    }

}

public class MlistFtpClient extends FTPClient {

    @Override
    public FTPFile[] listFiles(String pathname) throws IOException {
        return super.mlistDir(pathname);
    }
}

@EnableIntegration
@Configuration
public class FtpSyncConf {

    private static final Logger log = LoggerFactory.getLogger(FtpSyncConf.class);

    public static final String LOCAL_DIR = "/tmp/received";

    @Bean(name = "ftpMetaData")
    public ConcurrentMetadataStore ftpMetaData() {
        return new SimpleMetadataStore();
    }

    @Bean(name = "localMetaData")
    public ConcurrentMetadataStore localMetaData() {
        return new SimpleMetadataStore();
    }

    @Bean(name = "ftpFileSyncer")
    public FtpUpdatingFileSynchronizer ftpFileSyncer(
            @Qualifier("ftpMetaData") ConcurrentMetadataStore metadataStore) {

        MlistFtpSessionFactory ftpSessionFactory = new MlistFtpSessionFactory();
        ftpSessionFactory.setHost("localhost");
        ftpSessionFactory.setPort(4444);
        ftpSessionFactory.setUsername("demo");
        ftpSessionFactory.setPassword("demo");

        FtpPersistentAcceptOnceFileListFilter fileFilter = new FtpPersistentAcceptOnceFileListFilter(metadataStore, "ftp");
        fileFilter.setFlushOnUpdate(true);
        FtpUpdatingFileSynchronizer ftpFileSync = new FtpUpdatingFileSynchronizer(ftpSessionFactory);
        ftpFileSync.setFilter(fileFilter);
        // ftpFileSync.setDeleteRemoteFiles(true);
        return ftpFileSync;
    }

    @Bean(name = "syncFtp")
    @InboundChannelAdapter(value = "inputChannel", poller = @Poller(fixedDelay = "500", maxMessagesPerPoll = "1"))
    public MessageSource<File> syncChannel(
            @Qualifier("localMetaData") ConcurrentMetadataStore metadataStore,
            @Qualifier("ftpFileSyncer") FtpUpdatingFileSynchronizer ftpFileSync) throws Exception {

        FtpInboundFileSynchronizingMessageSource messageSource = new FtpInboundFileSynchronizingMessageSource(ftpFileSync);
        File receiveDir = new File(LOCAL_DIR);
        receiveDir.mkdirs();
        messageSource.setLocalDirectory(receiveDir);
        messageSource.setLocalFilter(new FileSystemPersistentAcceptOnceFileListFilter(metadataStore, "local"));
        log.info("Message source bean created.");
        return messageSource;
    }

    @Bean(name = "inputChannel")
    public PollableChannel inputChannel() {

        QueueChannel channel = new QueueChannel();
        log.info("Message channel bean created.");
        return channel;
    }

}

/**
 * Copied from https://github.com/spring-projects/spring-integration-samples/tree/master/basic/ftp/src/test/java/org/springframework/integration/samples/ftp/support
 * @author Gunnar Hillert
 *
 */
public class TestUserManager extends AbstractUserManager {
    private BaseUser testUser;
    private BaseUser anonUser;

    private static final String TEST_USERNAME = "demo";
    private static final String TEST_PASSWORD = "demo";

    public TestUserManager(String homeDirectory) {
        super("admin", new ClearTextPasswordEncryptor());

        testUser = new BaseUser();
        testUser.setAuthorities(Arrays.asList(new Authority[] {new ConcurrentLoginPermission(1, 1), new WritePermission()}));
        testUser.setEnabled(true);
        testUser.setHomeDirectory(homeDirectory);
        testUser.setMaxIdleTime(10000);
        testUser.setName(TEST_USERNAME);
        testUser.setPassword(TEST_PASSWORD);

        anonUser = new BaseUser(testUser);
        anonUser.setName("anonymous");
    }

    public User getUserByName(String username) throws FtpException {
        if(TEST_USERNAME.equals(username)) {
            return testUser;
        } else if(anonUser.getName().equals(username)) {
            return anonUser;
        }

        return null;
    }

    public String[] getAllUserNames() throws FtpException {
        return new String[] {TEST_USERNAME, anonUser.getName()};
    }

    public void delete(String username) throws FtpException {
        throw new UnsupportedOperationException("Deleting of FTP Users is not supported.");
    }

    public void save(User user) throws FtpException {
        throw new UnsupportedOperationException("Saving of FTP Users is not supported.");
    }

    public boolean doesExist(String username) throws FtpException {
        return (TEST_USERNAME.equals(username) || anonUser.getName().equals(username)) ? true : false;
    }

    public User authenticate(Authentication authentication) throws AuthenticationFailedException {
        if(UsernamePasswordAuthentication.class.isAssignableFrom(authentication.getClass())) {
            UsernamePasswordAuthentication upAuth = (UsernamePasswordAuthentication) authentication;

            if(TEST_USERNAME.equals(upAuth.getUsername()) && TEST_PASSWORD.equals(upAuth.getPassword())) {
                return testUser;
            }

            if(anonUser.getName().equals(upAuth.getUsername())) {
                return anonUser;
            }
        } else if(AnonymousAuthentication.class.isAssignableFrom(authentication.getClass())) {
            return anonUser;
        }

        return null;
    }
}

2016 年 11 月 15 日更新:关于 xml 配置的注释。

xml 元素 inbound-channel-adapter 通过 org.springframework.integration.ftp.config.FtpInboundChannelAdapterParser 直接链接到 FtpInboundFileSynchronizer > 通过 FtpNamespaceHandler 通过 spring-integration-ftp-4.3.5.RELEASE.jar!/META-INF/spring.handlers。
继xml-custom之后引用指南，在本地 META-INF/spring.handlers 文件中指定自定义 FtpNamespaceHandler 应该允许您使用 FtpUpdatingFileSynchronizer 而不是 FtpInboundFileSynchronizer。虽然它对我来说不适用于单元测试，但正确的解决方案可能涉及创建额外/修改的 xsd 文件，以便常规 inbound-channel-adapter 使用常规 FtpInboundFileSynchronizer 和一个特殊的 inbound-updating-channel-adapter 正在使用 FtpUpdatingFileSynchronizer。正确地做到这一点有点超出了这个答案的范围。
不过，快速破解可以让您入门。您可以通过在本地项目中创建包 org.springframework.integration.ftp.config 和类 FtpNamespaceHandler 来覆盖默认的 FtpNamespaceHandler。内容如下图:

package org.springframework.integration.ftp.config;

public class FtpNamespaceHandler extends org.springframework.integration.config.xml.AbstractIntegrationNamespaceHandler {

    @Override
    public void init() {
        System.out.println("Initializing FTP updating file synchronizer.");
        // one updated line below, rest copied from original FtpNamespaceHandler
        registerBeanDefinitionParser("inbound-channel-adapter", new MyFtpInboundChannelAdapterParser());
        registerBeanDefinitionParser("inbound-streaming-channel-adapter",
                new FtpStreamingInboundChannelAdapterParser());
        registerBeanDefinitionParser("outbound-channel-adapter", new FtpOutboundChannelAdapterParser());
        registerBeanDefinitionParser("outbound-gateway", new FtpOutboundGatewayParser());
    }

}

package org.springframework.integration.ftp.config;

import org.springframework.integration.file.remote.synchronizer.InboundFileSynchronizer;
import org.springframework.integration.ftp.config.FtpInboundChannelAdapterParser;

public class MyFtpInboundChannelAdapterParser extends FtpInboundChannelAdapterParser {

    @Override
    protected Class<? extends InboundFileSynchronizer> getInboundFileSynchronizerClass() {
        System.out.println("Returning updating file synchronizer.");
        return FtpUpdatingFileSynchronizer.class;
    }

}

同时将 preserve-timestamp="true" 添加到 xml 文件以防止新的 IllegalArgumentException: for updating timestamps must be preserved。

关于java - Spring 集成 - AbstractInboundFileSynchronizer 不更新文件，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/40468855/