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Create a Data Access Object for HarperDB Data using JDBI


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

Create a DAO for the HarperDB Customers 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 MyCustomersDAO { //insert new data into HarperDB @SqlUpdate("INSERT INTO Customers (Country, CompanyName) values (:country, :companyName)") void insert(@Bind("country") String country, @Bind("companyName") String companyName); //request specific data from HarperDB (String type is used for simplicity) @SqlQuery("SELECT CompanyName FROM Customers WHERE Country = :country") String findCompanyNameByCountry(@Bind("country") String country); /* * close with no args is used to close the connection */ void close(); }

Open a Connection to HarperDB

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

Set the Server, User, and Password connection properties to connect to HarperDB. Set UseSSL to secure connections with TLS/SSL.

Built-in Connection String Designer

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

java -jar cdata.jdbc.harperdb.jar

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

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

jdbc:harperdb:Server=127.0.0.1;User=admin;Password=1234;

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:harperdb:Server=127.0.0.1;User=admin;Password=1234;"); MyCustomersDAO dao = dbi.open(MyCustomersDAO.class); //do stuff with the DAO dao.close();

Read HarperDB Data

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

//disply the result of our 'find' method String companyName = dao.findCompanyNameByCountry("US"); System.out.println(companyName);

Write HarperDB Data

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

//add a new entry to the Customers entity dao.insert(newCountry, newCompanyName);

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

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