Create a Data Access Object for SFTP Data using JDBI

JDBI is a SQL convenience library for Java that exposes two different style APIs, a fluent style and a SQL object style. The CData JDBC Driver for SFTP integrates connectivity to live SFTP data in Java applications. By pairing these technologies, you gain simple, programmatic access to SFTP data. This article explains how to build a basic Data Access Object (DAO) and the accompanying code to read and write SFTP data.

Create a DAO for the SFTP MyDirectory Entity

The interface below declares the desired behavior for the SQL object to create a single method for each SQL statement to be implemented.

public interface MyMyDirectoryDAO {
 //insert new data into SFTP
 @SqlUpdate("INSERT INTO MyDirectory (FilePath, Filename) values (:filePath, :filename)")
 void insert(@Bind("filePath") String filePath, @Bind("filename") String filename);

 //request specific data from SFTP (String type is used for simplicity)
 @SqlQuery("SELECT Filename FROM MyDirectory WHERE FilePath = :filePath")
 String findFilenameByFilePath(@Bind("filePath") String filePath);

 /*
 * close with no args is used to close the connection
 */
 void close();
}

Open a Connection to SFTP

Collect the necessary connection properties and construct the appropriate JDBC URL for connecting to SFTP.

SFTP can be used to transfer files to and from SFTP servers using the SFTP Protocol. To connect, specify the RemoteHost;. service uses the User and Password and public key authentication (SSHClientCert). Choose an SSHAuthMode and specify connection values based on your selection.

Set the following connection properties to control the relational view of the file system:

• RemotePath: Set this to the current working directory.
• TableDepth: Set this to control the depth of subfolders to report as views.
• FileRetrievalDepth: Set this to retrieve files recursively and list them in the Root table.

Stored Procedures are available to download files, upload files, and send protocol commands. See gdatamodel for more on using SQL to interact with the server.

Built-in Connection String Designer

For assistance in constructing the JDBC URL, use the connection string designer built into the SFTP JDBC Driver. Either double-click the JAR file or execute the jar file from the command-line.

java -jar cdata.jdbc.sftp.jar

Fill in the connection properties and copy the connection string to the clipboard.

👁 Using the built-in connection string designer to generate a JDBC URL (Salesforce is shown.)

A connection string for SFTP will typically look like the following:

jdbc:sftp:RemoteHost=MyFTPServer;

Use the configured JDBC URL to obtain an instance of the DAO interface. The particular method shown below will open a handle bound to the instance, so the instance needs to be closed explicitly to release the handle and the bound JDBC connection.

DBI dbi = new DBI("jdbc:sftp:RemoteHost=MyFTPServer;");
MyMyDirectoryDAO dao = dbi.open(MyMyDirectoryDAO.class);

//do stuff with the DAO

dao.close();

Read SFTP Data

With the connection open to SFTP, simply call the previously defined method to retrieve data from the MyDirectory entity in SFTP.

//disply the result of our 'find' method
String filename = dao.findFilenameByFilePath("/documents/doc.txt");
System.out.println(filename);

Write SFTP Data

It is also simple to write data to SFTP, using the previously defined method.

//add a new entry to the MyDirectory entity
dao.insert(newFilePath, newFilename);

Since the JDBI library is able to work with JDBC connections, you can easily produce a SQL Object API for SFTP by integrating with the CData JDBC Driver for SFTP. Download a free trial and work with live SFTP data in custom Java applications today.