SFTP Spring集成的文件轮询和过滤问题

Question

I am trying to pull remote files through SFTP Spring Integration and dump into my local drive, and kick-off a Spring Batch Job (Step-1 to read, process & write), followed by Step-2 where a Tasklet archives the local file downloaded to another location locally and deletes the downloaded file.

Assuming the files being downloaded is "data.service", "data.maintenance" and "data.transaction". I am only processing "data.service" but all 3 are archived and deleted.

I want the above steps to happen at a specific interval assuming that a new set of files will be overwritten at the remote location.

Bean def

<bean id="acceptAllFileListFilter" class="org.springframework.integration.file.filters.AcceptAllFileListFilter"/>
<bean id="acceptOnceFileListFilter" class="org.springframework.integration.file.filters.AcceptOnceFileListFilter"/>

conf

<int-sftp:inbound-channel-adapter id="sftpInbondAdapter"
        channel="inboundFileChannel"
        session-factory="sftpSessionFactory"
        local-directory="file:${inbound.local.directory}"
        remote-directory="${inbound.remote.directory}"
        auto-create-local-directory="true"
        delete-remote-files="false"
        preserve-timestamp="true"
        filename-pattern="*.*"
        local-filter="acceptAllFileListFilter" >
    <int:poller max-messages-per-poll="-1" fixed-rate="60000" />
</int-sftp:inbound-channel-adapter>

What is happening now is... The above triggers this sequence and runs in an unending loop, without fetching the new files from remote. Details as below:

I start with an empty local folder, and remote server has all 3 files [Start the program]

1. Spring Integration program downloads all 3 files to local location
2. Spring Batch Job Step-1 gets triggered Tasklet (Step-2) archives the
3. local files Tasklet (Step-2) deletes the local files Spring
4. Integration program downloads all 3 files to local location (why???)
5. program keeps running Step-1 to Step-5 in an unending loop
6. New file dropped on the remote server, same (1) to (5) no job triggered

Tried replacing as below, but the program just runs once, ie, from (1) to (5) and nothing happens

        local-filter="acceptOnceFileListFilter" >

Expected

1. Spring Integration program downloads all 3 files to local location
2. Spring Batch Job Step-1 gets triggered
3. Tasklet (Step-2) archives the local files
4. Tasklet (Step-2) deletes the local files
5. Spring Integration program waits for new files to be dropped in the remote location (polls every 60000 ms)
6. New file dropped on the remote server
7. Start with (1) through (6)

Per suggestion on a different post I have a unique job parameter as below:

@Transformer
public JobLaunchRequest toRequest(Message<File> message) {
    JobParametersBuilder jobParametersBuilder = new JobParametersBuilder();
    jobParametersBuilder.addString(fileParameterName, message.getPayload().getAbsolutePath());
    jobParametersBuilder.addLong("currentTime", new Long(System.currentTimeMillis()));
    return new JobLaunchRequest(job, jobParametersBuilder.toJobParameters());
}

Tried with different combinations of filter, none served my purpose. Any sample would be of great help, struggling with this since last week.

Here's my change per the suggestions:

Adding a composite filter as below, but what would be the argument that will be passed to SftpPersistentAcceptOnceFileListFilter? I could not see any samples in the internet.

<bean id="compositeFilter" class="org.springframework.integration.file.filters.CompositeFileListFilter">
    <constructor-arg>
        <list>
            <bean class="org.springframework.integration.file.filters.FileSystemPersistentAcceptOnceFileListFilter"/>
            <bean class="org.springframework.integration.sftp.filters.SftpPersistentAcceptOnceFileListFilter">
            </bean>                     
        </list>
    </constructor-arg>
</bean>

Including in the adapter as below:

<int-sftp:inbound-channel-adapter id="sftpInbondAdapter"
        channel="inboundFileChannel"
        session-factory="sftpSessionFactory"
        local-directory="file:${inbound.local.directory}"
        remote-directory="${inbound.remote.directory}"
        auto-create-local-directory="true"
        delete-remote-files="false"  
        filter="compositeFilter">
    <int:poller max-messages-per-poll="-1" fixed-rate="600000" />
</int-sftp:inbound-channel-adapter>

Update - Changes after adding persistent filter:

<int-sftp:inbound-channel-adapter id="sftpInbondAdapter"
        channel="inboundFileChannel"
        session-factory="sftpSessionFactory"
        local-directory="file:${inbound.local.directory}"
        remote-directory="file:${inbound.remote.directory}"
        auto-create-local-directory="false"
        delete-remote-files="false"  
        filter="compositeFilter"
        >
    <int:poller max-messages-per-poll="-1" fixed-rate="60000" />
</int-sftp:inbound-channel-adapter>

<bean id="compositeFilter" class="org.springframework.integration.file.filters.CompositeFileListFilter">
    <constructor-arg>
        <list>
            <bean class="org.springframework.integration.file.filters.FileSystemPersistentAcceptOnceFileListFilter">
                <constructor-arg name="store" ref="metadataStore"/>
                <constructor-arg value="*.*"/>
            </bean>
            <bean class="org.springframework.integration.sftp.filters.SftpPersistentAcceptOnceFileListFilter">
                <constructor-arg name="store" ref="metadataStore"/>
                <constructor-arg value="*.*"/>
            </bean>
        </list>
    </constructor-arg>
</bean>

<bean id="redisConnectionFactory" class="org.springframework.data.redis.connection.jedis.JedisConnectionFactory">
    <property name="port" value="7379"/>
</bean>

<bean name="metadataStore" class="org.springframework.integration.redis.metadata.RedisMetadataStore">
    <constructor-arg name="connectionFactory" ref="redisConnectionFactory"/>
</bean>

This gives me the exception as below. I tried the suggestions in the Spring forum, but I don't have a connection issues.

2014-07-17 22:27:14,139 [task-scheduler-1] INFO com.jcraft.jsch - Authentication succeeded (keyboard-interactive). 2014-07-17 22:27:14,192 [task-scheduler-1] INFO com.jcraft.jsch - Disconnecting from localhost port 22 2014-07-17 22:27:14,195 [task-scheduler-1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Returning cached instance of singleton bean 'errorChannel' 2014-07-17 22:27:14,197 [task-scheduler-1] DEBUG org.springframework.integration.channel.PublishSubscribeChannel - preSend on channel 'errorChannel', message: [Payload MessagingException content=org.springframework.messaging.MessagingException: Problem occurred while synchronizing remote to local directory][Headers={id=84cccecf-20ec-f67b-3f74-a938bf9abf3d, timestamp=1405661234197}] 2014-07-17 22:27:14,197 [task-scheduler-1] DEBUG org.springframework.integration.handler.LoggingHandler - (inner bean)#22 received message: [Payload MessagingException content=org.springframework.messaging.MessagingException: Problem occurred while synchronizing remote to local directory][Headers={id=84cccecf-20ec-f67b-3f74-a938bf9 abf3d, timestamp=1405661234197}] 2014-07-17 22:27:14,199 [task-scheduler-1] ERROR org.springframework.integration.handler.LoggingHandler - org.springframework.messaging.MessagingException: Problem occurred while synchronizing remote to local directory at org.springframework.integration.file.remote.synchronizer.AbstractInboundFileSynchronizer.synchronizeToLocalDirectory(AbstractInboundFileSynchronizer.java:193) at org.springframework.integration.file.remote.synchronizer.AbstractInboundFileSynchronizingMessageSource.receive(AbstractInboundFileSynchronizingMessageSource.java:167) at org.springframework.integration.endpoint.SourcePollingChannelAdapter.receiveMessage(SourcePollingChannelAdapter.java:124) at org.springframework.integration.endpoint.AbstractPollingEndpoint.doPoll(AbstractPollingEndpoint.java:187) at org.springframework.integration.endpoint.AbstractPollingEndpoint.access$000(AbstractPollingEndpoint.java:52) at org.springframework.integration.endpoint.AbstractPollingEndpoint$1. call(AbstractPollingEndpoint.java:146) at org.springframework.integration.endpoint.AbstractPollingEndpoint$1.call(AbstractPollingEndpoint.java:143) at org.springframework.integration.endpoint.AbstractPollingEndpoint$Poller$1.run(AbstractPollingEndpoint.java:278) at org.springframework.integration.util.ErrorHandlingTaskExecutor$1.run(ErrorHandlingTaskExecutor.java:52) at org.springframework.core.task.SyncTaskExecutor.execute(SyncTaskExecutor.java:50) at org.springframework.integration.util.ErrorHandlingTaskExecutor.execute(ErrorHandlingTaskExecutor.java:49) at org.springframework.integration.endpoint.AbstractPollingEndpoint$Poller.run(AbstractPollingEndpoint.java:272) at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:54) at org.springframework.scheduling.concurrent.ReschedulingRunnable.run(ReschedulingRunnable.java:81) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:439) at java.util.concurrent.Future Task$Sync.innerRun(FutureTask.java:303) at java.util.concurrent.FutureTask.run(FutureTask.java:138) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:98) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:206) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918) at java.lang.Thread.run(Thread.java:695) Caused by: org.springframework.messaging.MessagingException: Failed to execute on session at org.springframework.integration.file.remote.RemoteFileTemplate.execute(RemoteFileTemplate.java:311) at org.springframework.integration.file.remote.synchronizer.AbstractInboundFileSynchronizer.synchronizeToLocalDirectory(AbstractInboundFileSynchronizer.java:167) ... 21 more Caused by: java.lang.ClassCastException: com.jcraft.jsch.ChannelSftp$LsEntry cannot be c ast to java.io.File at org.springframework.integration.file.filters.FileSystemPersistentAcceptOnceFileListFilter.fileName(FileSystemPersistentAcceptOnceFileListFilter.java:28) at org.springframework.integration.file.filters.AbstractPersistentAcceptOnceFileListFilter.buildKey(AbstractPersistentAcceptOnceFileListFilter.java:88) at org.springframework.integration.file.filters.AbstractPersistentAcceptOnceFileListFilter.accept(AbstractPersistentAcceptOnceFileListFilter.java:48) at org.springframework.integration.file.filters.AbstractFileListFilter.filterFiles(AbstractFileListFilter.java:40) at org.springframework.integration.file.filters.CompositeFileListFilter.filterFiles(CompositeFileListFilter.java:97) at org.springframework.integration.file.remote.synchronizer.AbstractInboundFileSynchronizer.filterFiles(AbstractInboundFileSynchronizer.java:157) at org.springframework.integration.file.remote.synchronizer.AbstractInboundFileSynchronizer$1.doInSession(AbstractInboundFileSynchronizer.java:1 73) at org.springframework.integration.file.remote.synchronizer.AbstractInboundFileSynchronizer$1.doInSession(AbstractInboundFileSynchronizer.java:167) at org.springframework.integration.file.remote.RemoteFileTemplate.execute(RemoteFileTemplate.java:302) ... 22 more

2014-07-17 22:27:14,199 [task-scheduler-1] DEBUG org.springframework.integration.channel.PublishSubscribeChannel - postSend (sent=true) on channel 'errorChannel', message: [Payload MessagingException content=org.springframework.messaging.MessagingException: Problem occurred while synchronizing remote to local directory][Headers={id=84cccecf-20ec-f67b-3f74-a938bf9abf3d, timestamp=1405661234197}]

Update post removing FileSystemPersistentAcceptOnceFileListFilter filter leaving the 'SftpPersistentAcceptOnceFileListFilter'

2014-07-18 09:29:21,942 [task-scheduler-3] INFO com.jcraft.jsch - Authentications that can continue: publickey,keyboard-interactive,password 2014-07-18 09:29:21,942 [task-scheduler-3] INFO com.jcraft.jsch - Next authentication method: publickey 2014-07-18 09:29:21,942 [task-scheduler-3] INFO com.jcraft.jsch - Authentications that can continue: keyboard-interactive,password 2014-07-18 09:29:21,942 [task-scheduler-3] INFO com.jcraft.jsch - Next authentication method: keyboard-interactive 2014-07-18 09:29:22,022 [task-scheduler-3] INFO com.jcraft.jsch - Authentication succeeded (keyboard-interactive). 2014-07-18 09:29:22,067 [task-scheduler-3] DEBUG org.springframework.data.redis.core.RedisConnectionUtils - Opening RedisConnection 2014-07-18 09:29:22,068 [task-scheduler-3] INFO com.jcraft.jsch - Disconnecting from localhost port 22 2014-07-18 09:29:22,068 [task-scheduler-3] DEBUG org.springframework.integration.channel.PublishSubscribeChannel - preSend on channel 'errorChannel', message: [Payload MessagingException content=org.springframework.messaging.MessagingException: Problem occurred while synchronizing remote to local directory][Headers={id=55304e38-6f82-8350-e763-0f5bcb507788, timestamp=1405700962068}] 2014-07-18 09:29:22,068 [Connect thread localhost session] INFO com.jcraft.jsch - Caught an exception, leaving main loop due to Socket closed 2014-07-18 09:29:22,068 [task-scheduler-3] DEBUG org.springframework.integration.handler.LoggingHandler - (inner bean)#22 received message: [Payload MessagingException content=org.springframework.messaging.MessagingException: Problem occu rred while synchronizing remote to local directory][Headers={id=55304e38-6f82-8350-e763-0f5bcb507788, timestamp=1405700962068}] 2014-07-18 09:29:22,069 [task-scheduler-3] ERROR org.springframework.integration.handler.LoggingHandler - org.springframework.messaging.MessagingException: Problem occurred while synchronizing remote to local directory at org.springframework.integration.file.remote.synchronizer.AbstractInboundFileSynchronizer.synchronizeToLocalDirectory(AbstractInboundFileSynchronizer.java:193) at org.springframework.integration.file.remote.synchronizer.AbstractInboundFileSynchronizingMessageSource.receive(AbstractInboundFileSynchronizingMessageSource.java:167) at org.springframework.integration.endpoint.SourcePollingChannelAdapter.receiveMessage(SourcePollingChannelAdapter.java:124) at org.springframework.integration.endpoint.AbstractPollingEndpoint.doPoll(AbstractPollingEndpoint.java:187) at org.springframework.integration.endpoint.AbstractPollingEndpoint.access$000(Abstract PollingEndpoint.java:52) at org.springframework.integration.endpoint.AbstractPollingEndpoint$1.call(AbstractPollingEndpoint.java:146) at org.springframework.integration.endpoint.AbstractPollingEndpoint$1.call(AbstractPollingEndpoint.java:143) at org.springframework.integration.endpoint.AbstractPollingEndpoint$Poller$1.run(AbstractPollingEndpoint.java:278) at org.springframework.integration.util.ErrorHandlingTaskExecutor$1.run(ErrorHandlingTaskExecutor.java:52) at org.springframework.core.task.SyncTaskExecutor.execute(SyncTaskExecutor.java:50) at org.springframework.integration.util.ErrorHandlingTaskExecutor.execute(ErrorHandlingTaskExecutor.java:49) at org.springframework.integration.endpoint.AbstractPollingEndpoint$Poller.run(AbstractPollingEndpoint.java:272) at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:54) at org.springframework.scheduling.concurrent.ReschedulingRunnable.run(ReschedulingRunnable.java:81) at java.ut il.concurrent.Executors$RunnableAdapter.call(Executors.java:439) at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303) at java.util.concurrent.FutureTask.run(FutureTask.java:138) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:98) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:206) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918) at java.lang.Thread.run(Thread.java:695) Caused by: org.springframework.messaging.MessagingException: Failed to execute on session at org.springframework.integration.file.remote.RemoteFileTemplate.execute(RemoteFileTemplate.java:311) at org.springframework.integration.file.remote.synchronizer.AbstractInboundFileSynchronizer.synchronizeToLocalDirectory(AbstractInboundFileSynchronizer.java:167) ... 2 1 more Caused by: org.springframework.data.redis.RedisConnectionFailureException: Cannot get Jedis connection; nested exception is redis.clients.jedis.exceptions.JedisConnectionException: Could not get a resource from the pool at org.springframework.data.redis.connection.jedis.JedisConnectionFactory.fetchJedisConnector(JedisConnectionFactory.java:97) at org.springframework.data.redis.connection.jedis.JedisConnectionFactory.getConnection(JedisConnectionFactory.java:143) at org.springframework.data.redis.connection.jedis.JedisConnectionFactory.getConnection(JedisConnectionFactory.java:41) at org.springframework.data.redis.core.RedisConnectionUtils.doGetConnection(RedisConnectionUtils.java:128) at org.springframework.data.redis.core.RedisConnectionUtils.getConnection(RedisConnectionUtils.java:91) at org.springframework.data.redis.core.RedisConnectionUtils.getConnection(RedisConnectionUtils.java:78) at org.springframework.data.redis.core.RedisTemplate.execute(RedisTemplate.java:177) at org.springframework.data.redis.core.RedisTemplate.execute(RedisTemplate.java:152) at org.springframework.data.redi s.core.AbstractOperations.execute(AbstractOperations.java:84) at org.springframework.data.redis.core.DefaultHashOperations.putIfAbsent(DefaultHashOperations.java:179) at org.springframework.data.redis.core.DefaultBoundHashOperations.putIfAbsent(DefaultBoundHashOperations.java:91) at org.springframework.data.redis.support.collections.RedisProperties.putIfAbsent(RedisProperties.java:228) at org.springframework.integration.redis.metadata.RedisMetadataStore.putIfAbsent(RedisMetadataStore.java:139) at org.springframework.integration.file.filters.AbstractPersistentAcceptOnceFileListFilter.accept(AbstractPersistentAcceptOnceFileListFilter.java:51) at org.springframework.integration.file.filters.AbstractFileListFilter.filterFiles(AbstractFileListFilter.java:40) at org.springframework.integration.file.filters.CompositeFileListFilter.filterFiles(CompositeFileListFilter.java:97) at org.springframework.integration.file.remote.synchronizer.AbstractInboundFileSynchronizer.filterFiles(AbstractInbound FileSynchronizer.java:157) at org.springframework.integration.file.remote.synchronizer.AbstractInboundFileSynchronizer$1.doInSession(AbstractInboundFileSynchronizer.java:173) at org.springframework.integration.file.remote.synchronizer.AbstractInboundFileSynchronizer$1.doInSession(AbstractInboundFileSynchronizer.java:167) at org.springframework.integration.file.remote.RemoteFileTemplate.execute(RemoteFileTemplate.java:302) ... 22 more Caused by: redis.clients.jedis.exceptions.JedisConnectionException: Could not get a resource from the pool at redis.clients.util.Pool.getResource(Pool.java:42) at redis.clients.jedis.JedisPool.getResource(JedisPool.java:84) at redis.clients.jedis.JedisPool.getResource(JedisPool.java:10) at org.springframework.data.redis.connection.jedis.JedisConnectionFactory.fetchJedisConnector(JedisConnectionFactory.java:90) ... 41 more Caused by: redis.clients.jedis.exceptions.JedisConnectionException: java.net.ConnectException: Connection refused at redis.clients.jedis .Connection.connect(Connection.java:150) at redis.clients.jedis.BinaryClient.connect(BinaryClient.java:71) at redis.clients.jedis.BinaryJedis.connect(BinaryJedis.java:1783) at redis.clients.jedis.JedisFactory.makeObject(JedisFactory.java:65) at org.apache.commons.pool2.impl.GenericObjectPool.create(GenericObjectPool.java:819) at org.apache.commons.pool2.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:429) at org.apache.commons.pool2.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:360) at redis.clients.util.Pool.getResource(Pool.java:40) ... 44 more Caused by: java.net.ConnectException: Connection refused at java.net.PlainSocketImpl.socketConnect(Native Method) at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:382) at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:241) at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:228) at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:431) at java.net.Socket.connect(Socket.java:527) at red is.clients.jedis.Connection.connect(Connection.java:144) ... 51 more

2014-07-18 09:29:22,069 [task-scheduler-3] DEBUG org.springframework.integration.channel.PublishSubscribeChannel - postSend (sent=true) on channel 'errorChannel', message: [Payload MessagingException content=org.springframework.messaging.MessagingException: Problem occurred while synchronizing remote to local directory][Headers={id=55304e38-6f82-8350-e763-0f5bcb507788, timestamp=1405700962068}]

Answer 1

It could be the case that if the new files dropped on the server has same name(which are downloaded in the first iteration) then spring integration will not attempt to download the files again. "acceptOnceFileListFilter" seems like something that would restrict sftp integration component to download the same file again.

Update : Here is some sample code which polls a remote directory every 10 secs without introducing any filters(I am not sure why you need them, as you want to download the files regardless). Given that you dont want to change the file names, the only thing that you will have to make sure is that your downloaded local needs to deleted when the next file is dropped on the remote server. I verified it and worked fine for me.

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xmlns:int="http://www.springframework.org/schema/integration"
   xmlns:int-ftp="http://www.springframework.org/schema/integration/ftp"
   xsi:schemaLocation="http://www.springframework.org/schema/beans      http://www.springframework.org/schema/beans/spring-beans.xsd
   http://www.springframework.org/schema/integration http://www.springframework.org/schema/integration/spring-integration.xsd

   http://www.springframework.org/schema/integration/ftp http://www.springframework.org/schema/integration/ftp/spring-integration-ftp.xsd">


<int:channel id="incomingChannel"/>

<bean id="ftpClientFactory" class="org.springframework.integration.ftp.session.DefaultFtpSessionFactory">
    <property name="host" value="host"/>
    <property name="username" value="username"/>
    <property name="password" value="password"/>
</bean>

<!-- poll every 10 secs without worrying about file names-->

<int-ftp:inbound-channel-adapter id="triggerFtpInBound"
                                 channel="incomingChannel"
                                 auto-create-local-directory="true"
                                 local-directory="C:\home\temp\ftp"
                                 remote-directory="/export/home/rbaljinder/ftp-test"
                                 filename-pattern="*.*"
                                 session-factory="ftpClientFactory">
    <int:poller cron="1/10 * * * * *" max-messages-per-poll="1"/>
</int-ftp:inbound-channel-adapter>

UPDATE: seems working now.Added local-filter="acceptAllFileListFilter".

 <int-ftp:inbound-channel-adapter id="triggerFtpInBound"
                                 channel="incomingChannel"
                                 auto-create-local-directory="true"
                                 local-directory="C:\home\temp\ftp"
                                 remote-directory="/export/home/cwk2/ftp-test"
                                 filename-pattern="*.*"
                                 session-factory="ftpClientFactory"
                                 local-filter="acceptAllFileListFilter">
    <int:poller cron="1/10 * * * * *" max-messages-per-poll="1"/>
</int-ftp:inbound-channel-adapter>
<bean id="acceptAllFileListFilter"
      class="org.springframework.integration.file.filters.AcceptAllFileListFilter"/>
<int:service-activator id="jobServiceActivator"
                       input-channel="incomingChannel"
                       ref="triggerJobLauncher"
                       method="launch"/>

@Component("triggerJobLauncher")
public static class TriggerJobLauncher {

    @Autowired
    JobLauncher jobLauncher;

    public void launch(File file) throws Exception {
        System.out.println("test:" + file);
    }

}

Answer 2

Gist Here

Hopefully self-explanatory; it just prints the file name on the console, then deletes it.