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Create a Data Access Object for CSV Data using JDBI

A brief overview of creating a SQL Object API for CSV data in 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 CSV integrates connectivity to live CSV data in Java applications. By pairing these technologies, you gain simple, programmatic access to CSV data. This article walks through building a basic Data Access Object (DAO) and the accompanying code to read CSV data.

Create a DAO for the CSV Customer 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 MyCustomerDAO { //request specific data from CSV (String type is used for simplicity) @SqlQuery("SELECT TotalDue FROM Customer WHERE FirstName = :firstName") String findTotalDueByFirstName(@Bind("firstName") String firstName); /* * close with no args is used to close the connection */ void close(); }

Open a Connection to CSV

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

The DataSource property must be set to a valid local folder name.

Also, specify the IncludeFiles property to work with text files having extensions that differ from .csv, .tab, or .txt. Specify multiple file extensions in a comma-separated list. You can also set Extended Properties compatible with the Microsoft Jet OLE DB 4.0 driver. Alternatively, you can provide the format of text files in a Schema.ini file.

Set UseRowNumbers to true if you are deleting or updating in CSV. This will create a new column with the name RowNumber which will be used as key for that table.

Built-in Connection String Designer

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

java -jar cdata.jdbc.csv.jar

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

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

jdbc:csv:DataSource=MyCSVFilesFolder;

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:csv:DataSource=MyCSVFilesFolder;"); MyCustomerDAO dao = dbi.open(MyCustomerDAO.class); //do stuff with the DAO dao.close();

Read CSV Data

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

//disply the result of our 'find' method String totalDue = dao.findTotalDueByFirstName("Bob"); System.out.println(totalDue);

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