Retrieving files from FTP server using Spring Integration

As I mentioned in the heading we need to include the following maven dependency in our pom.xml. Here we use the spring-integration-ftp dependency to allow spring-boot to connect with the FTP server.

maven dependencies

Now let's implement the code.

Following is the code for the FTP configuration. I created an FTPConfiguration.java file.

FTPConfiguration.java

Now let’s see what we did here.

sf()

This method instantiates a DefaultFtpSessionFactory to access the FTP server and sets the localhost as the host, 2121 as the port, anonymous as the Username, and a null string as the password.

getFile()

This method defines and constructs an FTPOutboundGateway bypassing the sf() method, mget command (mget is the spring FTP adapter command that use to retrieve multiple files from the FTP server) and the payload argument. Here the ServiceActivator indicates that the gateway is a spring-managed bean. The output of this method is a set of files. I named it “fileResults”. And it saves the retrieved files in the downloads folder.

Here, FTPOutboundGateway is used to perform remote file operations and Payload is a set of data that can perform functions like get, ls, put and etc.

fileResults()

This method creates a DirectChannel and adds a wireTap bean to it as an interceptor.

Here the wireTap method creates a copy of the message to a secondary target while sending the original message to the main channel.

logger()

This method creates a logging handler object and sends the message to the logging channel. Here the wiretap channel is wired to the logging handler.

GateFile interface

Here I declared a MessagingGateway to this interface and FTP mget as the request channel and fileResults as the reply channel. Then the result is sent to the main method a list of string objects

Next, we have to create a runner method to run this as a spring application.

Following is the code which should include in the springApplication.java